JP2016099276A - Insulation resistance measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a correct insulation resistance value of a measurement object regardless of operation timing of a measurement start key.SOLUTION: A processing unit 20 is configured to: execute connection detection processing of detecting a connection of a first measurement terminal 11 to a ground electrode E, and connection of a second measurement terminal 12 to a positive electrode P; and execute insulation resistance measurement processing of acquiring an electric current value Ioff of an electric current I to be measured by an electric current measurement unit 18 in a state causing a voltage generation unit 13 to halt a generation of an inspection DC voltage Vm when detecting that either measurement terminal 11 and 12 are all connected, acquiring an electric current value Ion of an electric current I to be measured by the electric current measurement unit 18 in a state causing the voltage generation unit 13 to generate the inspection DC voltage Vm; and calculating an insulation resistance value Rof a sunlight power generation unit 2 on the basis of each of the electric current values Ioff and Ion and a voltage value Vm of the inspection DC voltage Vm.SELECTED DRAWING: Figure 1

Description

  The present invention is connected between one electrode in a measurement object that outputs a DC voltage from between the positive electrode and the negative electrode and a grounded part, and is measured when the DC voltage for inspection is not output to the measurement object. Insulation that measures the insulation resistance value between one electrode and the grounded part of the measurement object based on (current or voltage) and the amount of electricity measured when the test DC voltage is output to the measurement object The present invention relates to a resistance measuring device.

  As this type of insulation resistance measuring device, the present applicant has already proposed the insulation resistance measuring device disclosed in Patent Document 1 below. This insulation resistance measuring apparatus short-circuits a pair of output terminals with an insulation resistance value (insulation resistance value between one output terminal of a pair of output terminals and a grounded part) of a photovoltaic power generation unit as a measurement target. It is possible to measure without having to.

  This insulation resistance measuring device is first connected to either one of the pair of output terminals of the photovoltaic power generation unit and the grounding part. Next, in this state, when the start switch is operated, the insulation resistance measuring device performs an inspection process to inspect the insulation state between one output terminal of the photovoltaic power generation unit and the grounding part. Next, the insulation resistance measuring device applies (outputs) a test voltage to the photovoltaic power generation unit, and in this state, the current value of the current flowing between one output terminal of the photovoltaic power generation unit and the grounded portion. (First current value) is measured. Subsequently, the insulation resistance measuring apparatus stops the application (output) of the inspection voltage to the photovoltaic power generation unit, and the current value of the current flowing between the one output terminal of the photovoltaic power generation unit and the grounding part in this state (Second current value) is measured. Finally, the insulation resistance measuring device subtracts the second current value from the first current value, and obtains the current value obtained by this subtraction (current value excluding the influence of the voltage generated by the photovoltaic power generation by the photovoltaic power generation unit). ) And the voltage value of the inspection voltage, the insulation resistance value of the photovoltaic power generation unit is calculated.

Japanese Patent Laying-Open No. 2011-127893 (page 7-8, FIG. 1)

  However, the above insulation resistance measuring apparatus has the following problems to be improved. That is, in this insulation resistance measuring apparatus, when the start switch is operated, the processing including the measurement of the two current values (the first current value and the second current value) as described above is unconditionally executed. Therefore, in this insulation resistance measurement device, when the start switch is operated before the connection of the insulation resistance measurement device to the photovoltaic power generation unit is completed (that is, when the start switch is operated at an inappropriate timing). Has a problem to be improved that the insulation resistance value of the photovoltaic power generation unit cannot be accurately calculated (measured) because an incorrect current value is measured in the above two current value measurements. doing.

  The present invention has been made to improve such a problem, and has as its main object to provide an insulation resistance measuring device capable of measuring an accurate insulation resistance value of a measurement object regardless of the operation timing of the start switch. .

  In order to achieve the above object, an insulation resistance measuring apparatus according to claim 1 is a first measuring terminal connected to a grounding part in a measuring object that outputs a DC voltage between a positive electrode and a negative electrode, and the positive electrode and the negative electrode. A second measuring terminal connected to one of the electrodes, a current measuring unit for measuring a current value of a current flowing between the first measuring terminal and the second measuring terminal, and a test DC voltage A voltage generation unit capable of outputting from between the first measurement terminal and the second measurement terminal, and a processing unit, wherein the processing unit connects the first measurement terminal to the grounding portion and When it is detected that both the first measurement terminal and the second measurement terminal are connected by executing connection detection processing for detecting the connection of the second measurement terminal to the one electrode. , The voltage generator A first current value as the current value of the current measured by the current measurement unit in a state in which the generation of the inspection DC voltage is stopped is obtained, and the inspection DC voltage is applied to the voltage generation unit. The second current value as the current value of the current measured by the current measuring unit in the generated state is acquired, the acquired first current value and second current value, and the voltage of the DC voltage for inspection An insulation resistance measurement process for calculating an insulation resistance value of the measurement object based on the value is executed.

  According to a second aspect of the present invention, there is provided the insulation resistance measuring apparatus according to the first aspect, wherein the processing unit is configured to execute both the first detection process and the second detection process in the connection detection process. In the first detection process, the current value of the current measured by the current measurement unit in a state where the generation of the test DC voltage is stopped by the voltage generation unit is acquired as a first detection current value. And the first measurement terminal and the second measurement terminal when the first detection current value is greater than or equal to the first threshold current value as compared with a first threshold current value defined in advance. Are detected, and in the second detection process, the current value of the current measured by the current measurement unit in a state in which the voltage generation unit generates the test DC voltage. The second detection current And the first measurement terminal and the second measurement when the second detected current value is equal to or greater than the second threshold current value as compared with the second threshold current value defined in advance. It is detected that both terminals are connected, and the second detection process is executed when the first detection current value is less than the first threshold current value in the first detection process.

  The insulation resistance measurement device according to claim 3 is the insulation resistance measurement device according to claim 1, wherein the processing unit executes one of a first detection process and a second detection process in the connection detection process. In the first detection process, the current value of the current measured by the current measurement unit in a state where the generation of the test DC voltage is stopped by the voltage generation unit is first detected. When the first detection current value is greater than or equal to the first threshold current value as compared with a first threshold current value that is acquired as a current value and defined in advance, the first measurement terminal and the first The current measured by the current measuring unit in a state in which the two measuring terminals are connected and the voltage generating unit generates the test DC voltage in the second detection process. The current value of When the second detected current value is greater than or equal to the second threshold current value, the first measuring terminal is obtained as a second detected current value and compared with a second threshold current value defined in advance. And detecting that both of the second measurement terminals are connected.

The insulation resistance measurement device according to claim 4 is the insulation resistance measurement device according to any one of claims 1 to 3, wherein the second measurement terminal is equivalently defined as a reference potential, and the voltage generator is The generated DC voltage for inspection can be output from between the positive output terminal and the negative output terminal, and the resistance value R _LIM connected between the first measurement terminal and the positive output terminal A voltage divider that has a voltage limiting resistor having a resistance value R _DIV connected between the current limiting resistor and the positive-side output terminal and the reference potential, and divides and outputs a voltage applied to the voltage dividing resistor. Any one of a pressure unit, a discharge resistance having a resistance value R _DCH having one end connected to the first measurement terminal, and the negative output terminal and the other end of the discharge resistance is selectively used as the reference potential. Each of the resistance values R _LIM , R _DIV , R _DCH are defined in advance so as to satisfy the following formula (a), and the processing unit controls the switching connection unit to connect the other end of the discharge resistor in the insulation resistance measurement process. The current value Ioff as the first current value measured by the current measuring unit while being connected to a reference potential is acquired, and the reference potential is used as a reference based on the voltage output from the voltage dividing unit A first measurement process for measuring a voltage value Voff of a voltage of the first measurement terminal; and the switching connection unit is controlled to connect the negative output terminal to the reference potential and the voltage generation unit is controlled to A DC voltage for inspection is generated, the current value Ion as the second current value measured by the current measuring unit is acquired, and applied to the voltage dividing resistor based on the voltage output from the voltage dividing unit Said voltage A second measuring process of measuring the voltage value Von of a resistance calculation process of calculating the insulation resistance value R _X between the ground portion and the one electrode for said measurement target based on the following formula (b) Execute.
R _DCH // (R _LIM + R _DIV ) = R _LIM (a)
R _X = (Von−Voff−Ion × R _LIM ) / (Ion−Ioff) (b)

Insulation resistance measuring apparatus according to claim 5, wherein, in the insulation resistance measuring apparatus according to claim 4, wherein, the output resistance of the voltage generator is defined in R _TH, the output resistance R _TH and the resistance values R _LIM , R _DIV , R _DCH are defined in advance so as to satisfy the following formula (c).
R _DCH // (R _LIM + R _DIV ) = R _LIM + R _DIV // R _TH (c)

  In the insulation resistance measuring apparatus according to claim 1, when the processing unit performs connection detection processing and detects that both the first measurement terminal and the second measurement terminal are connected to the measurement target. Then, an insulation resistance measurement process for measuring (calculating) the insulation resistance value to be measured is executed.

  Therefore, according to this insulation resistance measurement device, the processing unit does not start the insulation resistance measurement process before the connection of the insulation resistance measurement device to the measurement target is completed. The occurrence of a situation where an incorrect insulation resistance value is measured (calculated) based on the two current values can be reliably prevented.

  In the insulation resistance measuring apparatus according to the second aspect, the processing unit executes both the first detection process and the second detection process in this order in the connection detection process. Therefore, according to this insulation resistance measuring apparatus, for example, the first detection of the current flowing due to a low voltage (for example, a DC voltage output from the photovoltaic power generation unit) such as a DC voltage output from the measurement target is performed. Not only when the measurement target is connected to the first measurement terminal and the second measurement terminal with an extremely low resistance value such that the current value is equal to or greater than the first threshold current value, With a resistance value (a resistance value that is not so large as to hinder measurement of the insulation resistance value) that the second detection current value of the current that flows due to a certain high voltage is greater than or equal to the second threshold current value Even when the measurement object is connected to the first measurement terminal and the second measurement terminal, the insulation resistance value can be measured.

  In the insulation resistance measuring apparatus according to claim 3, for example, the insulation resistance value may be measured only when the measurement target is connected to the first measurement terminal and the second measurement terminal with an extremely low resistance value. In some cases, only the first detection process is executed in the connection detection process. In addition, measurement is performed with a resistance value that is not so large as to hinder measurement of the insulation resistance value, regardless of whether the measurement target is connected to the first measurement terminal and the second measurement terminal with a very low resistance value. When the configuration may be such that the insulation resistance value is measured when the target is connected to the first measurement terminal and the second measurement terminal, only the second detection process is performed in the connection detection process.

  Therefore, in any of the insulation resistance measuring apparatuses adopting any of these configurations, the processing unit does not start the insulation resistance measurement process before the connection of the insulation resistance measuring apparatus to the measurement target is completed. The occurrence of a situation where an incorrect insulation resistance value is measured (calculated) based on the first current value and the second current value can be reliably prevented.

In the insulation resistance measuring apparatus according to claim 4, the resistance values R _LIM , R _DIV , and R _DCH of the current limiting resistor, the voltage dividing unit, and the discharge resistor are defined in advance so as to satisfy the above formula (a). That is, the current value of the current that flows due to the DC voltage of the measurement target when the discharge resistor is connected and the current of the current that flows due to the DC voltage of the measurement target when the discharge resistance is disconnected a state where the values are aligned, the processing unit calculates the insulation resistance value R _X based on the above formula (b). Therefore, according to this insulation resistance measuring apparatus, even in a configuration with a built-in discharge resistance, the processing unit does not start the insulation resistance measurement process before the connection of the insulation resistance measuring apparatus to the measurement target is completed. , while reliably prevent a situation that an incorrect insulation resistance R _X is measured (calculated) based on correctly without first current value and second current value, to accurately calculate the insulation resistance value R _X Can do.

In the insulation resistance measuring apparatus according to claim 5, the output resistance value R _TH of the voltage generation unit and the resistance values R _LIM , R _DIV , and R _{DCH of the} current limiting resistor, the voltage dividing unit, and the discharge resistance are expressed by the above formula (c ) In a state prescribed in advance so that the discharge resistance is connected, that is, the current value of the current flowing due to the DC voltage to be measured is disconnected from the discharge resistance, and the DC voltage for inspection There in a state in which the current value was aligned in a current flowing due to the DC voltage to be measured in a state being generated, processing unit calculates the insulation resistance value R _X based on the above formula (b). Therefore, according to this insulation resistance measuring apparatus, even in a configuration with a built-in discharge resistance, the processing unit does not start the insulation resistance measurement process before the connection of the insulation resistance measuring apparatus to the measurement target is completed. , while reliably prevent a situation that an incorrect insulation resistance R _X is measured (calculated) based on correctly without first current value and second current value, to accurately calculate the insulation resistance value R _X Can do.

1 is a configuration diagram of an insulation resistance measuring device 1. FIG. It is an equivalent circuit of the photovoltaic power generation unit 2 when the inside is viewed from the positive electrode P and the ground electrode E. It is an equivalent circuit of the insulation resistance measuring apparatus 1 and the photovoltaic power generation unit 2 in a state where the inspection DC voltage Vm is stopped and the discharge resistor 16 is connected. It is an equivalent circuit of the insulation resistance measuring apparatus 1 and the photovoltaic power generation unit 2 in a state where the DC voltage Vm for inspection is output and the discharge resistor 16 is disconnected. 3 is a flowchart of a main routine 50. 10 is a flowchart of a connection detection process 60. 10 is a flowchart of connection disconnection detection processing 70;

  Hereinafter, embodiments of an insulation resistance measuring apparatus will be described with reference to the accompanying drawings.

  First, the configuration of the insulation resistance measuring device will be described with reference to the drawings.

An insulation resistance measuring device 1 as an insulation resistance measuring device shown in FIG. 1 includes a first measurement terminal 11, a second measurement terminal 12, a voltage generation unit 13, a current limiting resistor 14, a voltage dividing unit 15, and a discharge resistor 16. , switch connection unit 17, current measurement unit 18, storage unit 19, includes a processing unit 20 and the operation unit 21, to measure the insulation resistance value _{R X} of the measurement object 2. Moreover, although the insulation resistance measuring apparatus 1 in this example is provided with the thermistor (for example, a positive temperature coefficient thermistor) 31 for protecting the output circuit of the voltage generation part 13, it can also be abbreviate | omitted.

  Moreover, in the insulation resistance measuring apparatus 1 of this example, the thing to output a DC voltage from between a positive electrode and a negative electrode is set as the measuring object 2. Hereinafter, as an example of the measurement object 2, a photovoltaic power generation that outputs a DC voltage Vp between the positive electrode P and the negative electrode N (to facilitate understanding of the invention, the voltage value of this voltage is also expressed by Vp). A description will be given with units (hereinafter also referred to as “solar power generation unit 2”).

In this photovoltaic power generation unit 2, as shown in FIG. 1, a ground electrode E as a ground part is grounded (connected to a ground potential). Further, in this photovoltaic power generation unit 2, when the resistance value (unknown) between the positive electrode P and the ground electrode E is R1, and the resistance value (unknown) between the negative electrode N and the ground electrode E is R2, An equivalent circuit of the photovoltaic power generation unit 2 viewed from the positive electrode P and the ground electrode E is expressed as shown in FIG. That is, this equivalent circuit has a DC voltage Vp and an insulation resistance value R between the positive electrode P and the ground electrode E, where Vp is a voltage (DC voltage) output from the solar power generation unit 2 by solar power generation. _X is a circuit connected in series. Incidentally, the insulation resistance value _{R X} is a respective above insulation resistance value R1, a parallel combined resistance value of R2 (R1 // R2). This equivalent circuit is the same as the equivalent circuit of the photovoltaic power generation unit 2 as viewed from the negative electrode N and the ground electrode E. The symbol “//” means a symbol indicating a parallel combined resistance value of two resistance values written on both sides thereof.

  The first measurement terminal 11 is connected to the grounding part E in the photovoltaic power generation unit 2 via the probe PL1. The second measurement terminal 12 is connected to one electrode (the positive electrode P in FIG. 1) of the positive electrode P and the negative electrode N in the photovoltaic power generation unit 2 via the probe PL2. Note that the first measurement terminal 11 including the probe PL1 can be regarded as the first measurement terminal 11, and the second measurement terminal 12 including the probe PL2 can be regarded as the second measurement. It can also be regarded as the terminal 12 for use. In addition, the second measurement terminal 12 is connected to a part (internal ground G) defined by the reference potential in the insulation resistance measurement apparatus 1 through the current measurement unit 18). The current measuring unit 18 generally has a configuration with extremely small internal resistance. Thereby, the second measurement terminal 12 is equivalently connected to the internal ground G (defined by the reference potential).

  The voltage generation unit 13 is controlled by the processing unit 20 to generate a test DC voltage Vm (in order to facilitate understanding of the invention, the voltage value of this voltage is also represented by Vm), An output is possible between the side output terminal 13a and the negative output terminal 13b. In this example, as an example, the voltage generator 13 generates a test DC voltage Vm by an output circuit (circuit configured as a floating circuit) electrically isolated from the internal ground G, and a pair of outputs of the output circuit. Output from the positive output terminal 13a and the negative output terminal 13b as terminals. Further, the negative side output terminal 13 b is connected to the terminal a of the switching connection portion 17. With this configuration, the voltage generation unit 13 uses the generated test DC voltage Vm as a voltage with reference to the potential of the negative output terminal 13b (the potential of the a terminal of the switching connection unit 17) between the output terminals 13a and 13b. Output from.

The current limiting resistor 14 is connected between the first measurement terminal 11 and the positive output terminal 13a. Further, the current limiting resistor 14 is defined by a resistance value R _LIM (known). In this case, since the insulation resistance measuring apparatus 1 of this example includes the thermistor 31 (resistance value R _TH (known)) for protecting the voltage generation unit 13 as described above, voltage generation in the current limiting resistor 14 is performed. One end on the part 13 side is output to the positive output terminal 13 a via the thermistor 31. When the thermistor 31 is omitted, one end on the voltage generator 13 side is directly connected to the positive output terminal 13a.

The voltage divider 15 is a voltage dividing resistor connected between the positive output terminal 13a (in this example, the thermistor 31 is provided, and therefore the connection point between the thermistor 31 and the current limiting resistor 14) and the internal ground G. (In FIG. 1, as an example, there are two resistors 15a and 15b connected in series, each having a known resistance value), and the voltage applied to the voltage dividing resistor is divided to obtain a divided voltage Vdi (understand the invention). For the sake of simplicity, this voltage value is also expressed as Vdi). In addition, the overall resistance value (the combined resistance value of the resistors 15a and 15b) of the _{voltage dividing} resistor is defined as a resistance value R _DIV (known).

The discharge resistor 16 has one end connected to the first measurement terminal 11 and the other end connected to the b terminal of the switching connection portion 17. Further, the discharge resistor 16 is defined by a resistance value R _DCH (known). The switching connection unit 17 includes an a terminal, a b terminal, and a c terminal, and any one of the a terminal and the b terminal can be connected to the c terminal. The c terminal is connected to the internal ground G. With this configuration, the switching connection unit 17 connects the negative output terminal 13b connected to the a terminal and the other end of the discharge resistor 16 connected to the b terminal to the internal ground G (reference potential). Selectively connect to.

  The current measuring unit 18 includes a pair of input terminals. In this example, as an example, one input terminal is connected to the second measurement terminal 12 and the other input terminal is connected to the internal ground G, so that the first 2 Connected between the measurement terminal 12 and the internal ground G. The current measuring unit 18 is configured in a state where the resistance value between the pair of input terminals is extremely small (a state close to zero Ω) in the same manner as a general ammeter. 2 When the photovoltaic power generation unit 2 is connected to the measurement terminal 12, the current value of the current I flowing between the measurement terminals 11 and 12 (Ioff and Ion described later) is accurately measured. Further, the current measuring unit 18 is configured to detect whether the photovoltaic power generation unit 2 is connected to the first measurement terminal 11 and the second measurement terminal 12 in a normal state. The current value of the current I flowing between 12 (Id1, Id2 described later) is accurately measured. Further, the current measuring unit 18 outputs current data Di indicating the measured current value to the processing unit 20.

The storage unit 19 includes a semiconductor memory or a hard disk device, and stores an operation program for the processing unit 20 in advance. In this operation program, the following equation (1) as the equation (b) for measuring (calculating) the insulation resistance value R _X of the photovoltaic power generation unit 2 includes known resistance values R _LIM , R _DIV , R _DCH , R _TH and resistance values of the resistors 15a and 15b are included. The storage unit 19 stores a first threshold current value Ith1 and a second threshold current value Ith2 that are used when detecting connection. The storage unit 19 stores a voltage value, a current value, a resistance value, and the like measured by the processing unit 20.
R _X = (Von−Voff−Ion × R _LIM ) / (Ion−Ioff) (1)

  Hereinafter, Formula (1) will be described based on an equivalent circuit of the insulation resistance measuring apparatus 1 and the photovoltaic power generation unit 2 shown in FIGS. 3 shows a state in which the other end of the discharge resistor 16 is connected to the internal ground G via the switching connection portion 17 and the DC voltage Vm for inspection from the insulation resistance measuring device 1 to the photovoltaic power generation unit 2. This is an equivalent circuit when output is stopped (when Vm is off). The negative output terminal 13b of the voltage generation unit 13 is disconnected from the internal ground G by the switching connection unit 17 and is in a floating state. For this reason, this equivalent circuit does not include the configuration of the voltage generator 13.

  4, the other end of the discharge resistor 16 is disconnected from the internal ground G by the switching connection portion 17, while the negative output terminal 13 b of the voltage generation unit 13 is connected to the internal ground G by the switching connection portion 17. It is an equivalent circuit when the test DC voltage Vm is output from the voltage generator 13 to the photovoltaic power generation unit 2 in the state (when Vm is on). For this reason, this equivalent circuit includes the inspection DC voltage Vm and the thermistor 31.

When the current value of the current I measured by the current measuring unit 18 (the current value as the first current value in this equivalent circuit when Vm is off is defined as Ioff) from the equivalent circuit of FIG. It is expressed as equation (2). Note that the current value Ioff in this case is the current value Ip1 of the current Ip1 that flows through the photovoltaic power generation unit 2 and the insulation resistance measuring device 1 due to the DC voltage Vp output from the photovoltaic power generation unit 2 by photovoltaic power generation. It becomes.
Ioff = Ip1 = Vp / [R _X + R _DCH // (R _LIM + R _DIV )] (2)

Further, the following expression (3) is an expression obtained by paying attention to a plurality of voltage components in the equivalent circuit of FIG. Among these voltage components, the voltage value Voff is equal to the voltage value Vdi of the divided voltage Vdi output from the voltage divider 15 by the processing unit 20 of the insulation resistance measuring apparatus 1 in this equivalent circuit state. Between both ends of the series connection circuit of the current limiting resistor 14 and the voltage dividing unit 15 calculated based on the resistance values of the resistors 15a and 15b constituting the voltage dividing unit 15 and the resistance value R _{LIM of} the current limiting resistor 14 This is a voltage value (a voltage value based on the potential of the internal ground G (reference potential)). The voltage value Voff is also the voltage value of the first measurement terminal 11.
Vp−R _X × Ip1 = −Voff (3)

  In the equivalent circuit of FIG. 4, the current Ip2 that flows due to the DC voltage Vp (to facilitate understanding of the invention, the current value of this current is also expressed as Ip2) and the DC voltage Vm for inspection are used. Current Im flows (in order to facilitate understanding of the invention, the current value of this current is also expressed by Im). Thus, the current value of the current I measured by the current measuring unit 18 (the current value as the second current value in this equivalent circuit when the test DC voltage Vm is on is Ion) A combined current value (Ip2 + Im) of the currents Ip2 and Im is obtained.

In this case, the current value Ip2 is expressed by the following formula (4).
Ip2 = Vp / (R _X + R _LIM + R _DIV // R _TH ) (4)

Further, the following formula (5) is a formula obtained by paying attention to a plurality of voltage components in the equivalent circuit of FIG. Among these voltage components, the voltage value Von is equal to the voltage value Vdi of the divided voltage Vdi output from the voltage divider 15 by the processing unit 20 of the insulation resistance measuring apparatus 1 in the state of this equivalent circuit. Voltage between both ends of the voltage divider 15 calculated based on each resistance value of the resistors 15a and 15b constituting the voltage divider 15 (divided value of the voltage divider 15) (application to the voltage divider 15) Voltage).
Von + Vp = Ion × (R _X + R _LIM ) (5)

By the way, in each equivalent circuit shown in FIGS. 3 and 4, the currents Ip1 and Ip2 that flow due to the DC voltage Vp output from the photovoltaic power generation unit 2 by photovoltaic power generation have the same value (Ip1 = Ip2). Must be aligned as follows. In this case, paying attention to the above formulas (2) and (4) for the currents Ip1 and Ip2, since each numerator is common to Vp, each denominator is the same, so that each current Ip1 and Ip2 is Be the same. Therefore, the following equation (6) is established under the condition that the respective denominators of the above equations (2) and (4) are the same, and the following equation (7) as the equation (c) is finally obtained from this equation (6). ) Is guided.
[R _X + R _DCH // (R _LIM + R _DIV )] = (R _X + R _LIM + R _DIV // R _TH ) (6)
R _DCH // (R _LIM + R _DIV ) = R _LIM + R _DIV // R _TH (7)

In the insulation resistance measuring device 1 of this example, each resistance value R _LIM , R _DIV , R _DCH , R of each current limiting resistor 14, voltage dividing unit 15, discharge resistor 16 and thermistor 31 constituting the insulation resistance measuring device 1. _The currents Ip1 and Ip2 are set to be the same by preliminarily defining _TH to satisfy the above formula (7).

Further, by paying attention to the above two formulas (3) and (5), the following formula (8) is derived by erasing the DC voltage Vp included in each formula, and the current value Ip1 is a current value. since the value Ioff, the current value Ip1 in the equation (8) by replacing the current value Ioff, above equation (1) is derived which represents the insulation resistance value _{R X.}
R _X = (Von−Voff−Ion × R _LIM ) / (Ion−Ip1) (8)

Focusing on (Ion−Ip1) as the denominator of the equation (8), as described above, the current value Ion is the combined current value (Ip2 + Im) of the currents Ip2 and Im, and this insulation resistance measuring device. 1, the resistance values R _LIM , R _DIV , R _DCH , and R _TH are defined in advance so as to satisfy the above equation (7) as described above, so that the currents Ip 1 and Ip 2 are the same. Is set. Therefore, in the insulation resistance measuring apparatus 1 of the present example, by subtracting the current value Ip1 from the current value Ion, the denominator of Expression (8), that is, the denominator of Expression (1) becomes only the current value Im. Due to the DC voltage Vp output from the photovoltaic power generation unit 2 by photovoltaic power generation, the influences of the currents Ip1 and Ip2 flowing through the photovoltaic power generation unit 2 and the insulation resistance measuring device 1 can be canceled.

  The processing unit 20 is configured by a computer including an A / D converter and a CPU, and measures the insulation resistance value Rx of the measurement target 2 by operating according to the operation program stored in the storage unit 19. The main routine 50 (a routine including a start instruction detection process, a connection detection process 60, an insulation resistance measurement process, etc., which will be described later) is executed. The operation unit 21 is provided with a measurement start key (start switch) (not shown). The operation unit 21 is configured to repeatedly output the measurement start signal S1 to the processing unit 20 and stop outputting the measurement start signal S1 every time the measurement start key is operated.

Next, a description will be given insulation resistance behavior of the insulation resistance measuring apparatus 1 for measuring a R _X for solar power generation unit 2.

  In this insulation resistance measuring apparatus 1, when the processing unit 20 shifts to the start-up state, the processing unit 20 first performs control on the switching connection unit 17 and connects the b terminal to the c terminal as shown by the solid line, thereby discharging The other end of the resistor 16 is connected to the internal ground G, and the control for the voltage generator 13 is executed to stop the generation of the inspection DC voltage Vm. Next, the main routine 50 shown in FIG. 5 is started.

In the main routine 50, the processing unit 20 first executes a start instruction detection process for detecting whether or not the measurement start signal S1 is output from the operation unit 21 (step 51). When the processing unit 20 detects the output of the measurement start signal S1 in the start instruction detection process, the processing unit 20 executes a connection detection process 60. With this configuration, the operator starts this process for the insulation resistance measuring apparatus 1 by operating the measurement start key of the operation unit 21 in a state where the insulation resistance measuring apparatus 1 has not started the connection detection process 60. It is possible to make it. The connection detecting process 60, as shown in FIG. 5, it is executed prior to the execution of the resistance calculation processing described later for measuring the insulation resistance value R _X (step 54).

  In this connection detection process 60, as shown in FIG. 6, the processing unit 20 first executes a first detection process. In the first detection process, the processing unit 20 first starts measuring the elapsed time tp after the execution of the connection detection process 60 and inputs the current data Di output from the current measurement unit 18. Then, based on the input current data Di, it is determined whether or not the current measuring unit 18 detects the current I (whether or not the current I flows through the current measuring unit 18) (step 61).

  Specifically, in step 61, the processing unit 20 determines the current value Id1 of the current I (first detected current value when the generation of the inspection DC voltage Vm is stopped based on the current data Di. , Also referred to as first detection current value Id1), is measured (calculated) and compared with the first threshold current value Ith1 read from the storage unit 19. When the first detection current value Id1 is equal to or greater than the first threshold current value Ith1 as a result of the comparison, the processing unit 20 detects the current I in the current measurement unit 18 (the current I is detected in the current measurement unit 18). It is flowing).

  In this case, when the photovoltaic power generation unit 2 is connected between the first measurement terminal 11 and the second measurement terminal 12, the insulation resistance measurement device 1 and the photovoltaic power generation unit 2 are connected as shown in FIG. A current path including the DC voltage Vp from the photovoltaic power generation unit 2 and the current measuring unit 18 of the insulation resistance measuring device 1 is formed. In this current path, a current Ip1 due to the DC voltage Vp can flow through the current measuring unit 18, but the current value of the current Ip1 (the first detected current value Id1) is determined by the connection state of the photovoltaic power generation unit 2. When it is good, it becomes larger than when the connection state is poor or when it is not connected. In this insulation resistance measuring apparatus 1, the first threshold current value Ith1 is defined in advance as a current value slightly larger than the current value of the current Ip1 when the connection state is poor (for example, about 150 nA).

  Thus, when the processing unit 20 determines in step 61 that the current Ip1 is detected (the current Ip1 flows through the current measurement unit 18), the first measurement terminal 11 and the second measurement terminal 12, it is determined that the solar power generation unit 2 is normally connected, and the first detection process and the connection detection process 60 are completed.

  On the other hand, when the processing unit 20 determines in step 61 that the current Ip1 is not detected (the current Ip1 is not flowing in the current measuring unit 18 or the current value is very small even if it is flowing), the measurement is performed. Whether or not the elapsed time tp is equal to or longer than a predetermined time T1 (for example, about 1 second) (that is, whether or not the time T1 has elapsed since the start of step 61). Step 61 is repeated while executing the process of determining (Step 62).

  While the processing unit 20 repeatedly executes the steps 61 and 62, the solar power generation unit 2 is normally connected between the first measurement terminal 11 and the second measurement terminal 12, so that the step 61 is performed. When it is determined that the current Ip1 is detected in step 1, the first detection process and the connection detection process 60 are completed. On the other hand, the processing unit 20 does not determine that the current Ip1 is detected in Step 61 while repeatedly executing Steps 61 and 62, and determines in Step 62 that the elapsed time tp is equal to or longer than the predetermined time T1. If so, the first detection process is completed and the second detection process is started.

  In the second detection process, the processing unit 20 executes a process of outputting the inspection DC voltage Vm (step 63). In this process, the processing unit 20 first performs control on the switching connection unit 17 and connects the a terminal to the c terminal as indicated by a broken line, thereby connecting the negative output terminal 13b of the voltage generation unit 13 to the internal terminal. Connect to ground G. As a result, the discharge resistor 16 is disconnected from the internal ground G. Next, the processing unit 20 executes control on the voltage generation unit 13 to generate the inspection DC voltage Vm. As a result, the DC voltage for inspection Vm (the DC voltage Vp of the photovoltaic power generation unit 2) from the positive output terminal 13a and the negative output terminal 13b of the voltage generator 13 with the potential of the internal ground G (reference potential) as a reference. Higher voltage) is output between the first measurement terminal 11 and the second measurement terminal 12.

  Subsequently, the processing unit 20 receives the current data Di output from the current measuring unit 18 and determines whether or not the current I is detected in the current measuring unit 18 based on the input current data Di ( It is determined whether or not the current I flows through the current measuring unit 18 (step 64).

  Specifically, in step 64, the processing unit 20 determines the current value Id2 of the current I (second detected current value when the generation of the inspection DC voltage Vm is stopped based on the current data Di. , Also referred to as second detection current value Id2), is measured (calculated) and compared with the second threshold current value Ith2 read from the storage unit 19. In this example, as an example, the second threshold current value Ith2 is defined as the same value as the first threshold current value Ith1, but may be defined as a different value. When the second detection current value Id2 is equal to or greater than the second threshold current value Ith2, as a result of this comparison, the processing unit 20 detects the current I in the current measurement unit 18 (the current I is detected in the current measurement unit 18). It is flowing).

  In this case, when the photovoltaic power generation unit 2 is connected between the first measurement terminal 11 and the second measurement terminal 12, the insulation resistance measurement device 1 and the photovoltaic power generation unit 2 are connected as shown in FIG. A current path including the DC voltage Vp from the photovoltaic power generation unit 2, the inspection DC voltage Vm from the insulation resistance measuring device 1, and the current measuring unit 18 is formed. In this current path, in addition to the current Ip2 caused by the DC voltage Vp, the current Im caused by the test DC voltage Vm can flow through the current measuring unit 18.

For this reason, when the photovoltaic power generation unit 2 is not connected between the first measurement terminal 11 and the second measurement terminal 12, neither the current Ip2 nor the current Im flows in the first place, so the calculation is based on the current data Di. The second detection current value Id2 of the current I to be applied does not become equal to or greater than the second threshold current value Ith2, but the first measurement terminal 11 and the second measurement terminal 12 are in contact with the photovoltaic power generation unit 2. Even if the resistance value of the resistor is in a very good contact state (the first detected current value Id1 of the current I flowing due to a low voltage such as the DC voltage Vp of the photovoltaic power generation unit 2), the first threshold current In the first detection process, it is determined that the current Ip1 is not detected because the resistance value is slightly larger than the resistance value in the case of an extremely low resistance value that is equal to or greater than the value Ith1, but the insulation resistance value R _If the magnitude is not so large as to inhibit the measurement of _X , the calculated second detection current value Id2 may be equal to or greater than the second threshold current value Ith2.

In this insulation resistance measuring apparatus 1, the processing unit 20 detects the current I even when the second detected current value Id2 is equal to or greater than the second threshold current value Ith2 (current measurement). It is determined that the current I flows through the portion 18. In other words, the processing unit 20 determines that the solar power generation unit 2 is connected with measurable state of the insulation resistance value R _X between the first measurement terminal 11 and the second measurement terminal 12, the first 2 The detection process is completed. In this example, when starting the execution of the second detection process, the processing unit 20 determines in step 64 that the current I is detected (the second detection current value Id2 of the current I is the second value). The second detection process is continued until the threshold current value Ith2 is greater than or equal to the threshold current value Ith2.

Processing unit 20, after completing the second detection processing (i.e., connected photovoltaic unit 2 in measurable state of the insulation resistance value R _X between the first measurement terminal 11 and the second measurement terminal 12 After having been detected, the control on the voltage generator 13 is executed to stop the generation of the inspection DC voltage Vm (step 65), and then the discharge process (step 66) is executed. In this discharge process, the processing unit 20 performs control on the switching connection unit 17 and connects the b terminal to the c terminal as shown by the solid line, thereby connecting the negative output terminal 13b of the voltage generation unit 13 to the internal ground. Disconnect from G and connect the discharge resistor 16 to the internal ground G. Thereby, the insulation resistance measuring apparatus 1 and the photovoltaic power generation unit 2 shift from the state of the equivalent circuit shown in FIG. 4 to the state of the equivalent circuit shown in FIG.

In the general photovoltaic power generation unit 2, capacitive components exist between the positive electrode P and the ground electrode E and between the negative electrode N and the ground electrode E, respectively. Accordingly, these capacitance components are charged by the inspection DC voltage Vm output to the photovoltaic power generation unit 2 in the above-described step 63. The remains of these capacity components have been charged, but have undesirable effects on the accurate measurement of the insulation resistance value R _X, that the discharge resistor 16 as described above is connected to the internal ground G, for the first measurement since terminal 11 is connected to the internal ground G through the discharge resistor 16, the capacitance component of the solar power generation unit 2 is discharged, solar power generation unit 2 is capable of accurate measurement state of the insulation resistance value R _X Migrate to The processing unit 20 completes the connection detection processing 60 after maintaining the state of step 66 for a predetermined time (that is, after the capacity component of the photovoltaic power generation unit 2 is sufficiently discharged), and FIG. Return to the main routine 50 shown in FIG.

  After returning to the main routine 50, the processing unit 20 executes the first measurement process (step 52). In the first measurement process, the processing unit 20 inputs the current data Di output from the current measurement unit 18, and outputs from the solar power generation unit 2 by solar power generation based on the input current data Di. The current value of the current I flowing in the photovoltaic power generation unit 2 and the insulation resistance measuring device 1 (that is, flowing in the current measuring unit 18) due to the direct current voltage Vp (in the equivalent circuit shown in FIG. 3 described above) (Current value Ioff) is measured (calculated) and stored in the storage unit 19.

Further, the processing unit 20 receives the divided voltage Vdi output from the voltage dividing unit 15 and converts it into digital data by an A / D converter, and the divided voltage Vdi indicated by the converted digital data. The current limiting resistor 14 and the voltage dividing unit 15 are connected in series based on the voltage value Vdi, the resistance values of the resistors 15a and 15b constituting the voltage dividing unit 15, and the resistance value R _LIM of the current limiting resistor 14. The voltage value Voff between both ends of the connection circuit (which is also the voltage value of the first measurement terminal 11) is measured (calculated) and stored in the storage unit 19. Thereby, the first measurement process is completed.

  Next, the processing unit 20 executes a second measurement process (step 53). In the second measurement process, the processing unit 20 first performs control on the switching connection unit 17 and connects the a terminal to the c terminal as indicated by a broken line, thereby allowing the negative output terminal of the voltage generation unit 13 to be connected. 13b is connected to the internal ground G. As a result, the discharge resistor 16 is disconnected from the internal ground G. Next, the processing unit 20 executes control on the voltage generation unit 13 to generate the inspection DC voltage Vm. As a result, a test DC voltage Vm based on the potential (reference potential) of the internal ground G is output from between the positive output terminal 13a and the negative output terminal 13b of the voltage generator 13.

At this time, the processing unit 20 receives the divided voltage Vdi output from the voltage dividing unit 15 and converts it into digital data by an A / D converter, and the divided voltage indicated by the converted digital data. Based on the voltage value Vdi of the voltage Vdi and the resistance values of the resistors 15a and 15b constituting the voltage divider 15, the voltage value Von between both ends of the voltage divider 15 is measured (calculated). Further, the processing unit 20 performs an operation of changing the voltage value Vm of the test DC voltage Vm to the voltage generating unit 13 so that the measured voltage value Von is maintained at a predetermined voltage value. Let it run. Thereby, the insulation resistance measuring apparatus 1 and the photovoltaic power generation unit 2 shift to the state of the equivalent circuit shown in FIG. Further, the processing unit 20 stores the voltage value Von in a state maintained constant in the storage unit 19. In addition, in the insulation resistance measuring apparatus 1, the voltage value Von, which is also the voltage of the terminal on the first measurement terminal 11 side (terminal on the output side) in the thermistor 31, is thus controlled to be constant. Can be regarded as the output resistance arranged on the output line of the voltage generator 13 (that is, the resistance value R _TH of the thermistor 31 can also be regarded as the output resistance value of the voltage generator 13).

  Further, in this state, the processing unit 20 inputs the current data Di output from the current measurement unit 18 and, based on the input current data Di, the DC voltage output from the photovoltaic power generation unit 2. The photovoltaic power generation unit 2 and the current value Ip2 of the current Ip2 flowing through the photovoltaic power generation unit 2 and the insulation resistance measuring device 1 due to Vp, and the test DC voltage Vm output from the voltage generator 13 and The combined current value (Ip2 + Im) of the current Im flowing through the insulation resistance measuring apparatus 1 is measured (calculated) as the current value Ion and stored in the storage unit 19. Thereby, the second measurement process is completed.

Subsequently, the processing unit 20 executes a resistance calculation process (step 54). In this resistance calculation process, the processing unit 20 includes the current values Ioff and Ion and the voltage values Voff and Von stored in the storage unit 19, the resistance value R _LIM defined in the operation program, and the formula (1 ) and on the basis, to calculate the insulation resistance value R _X of the formula (1), in the storage unit 19.

Next, the processing unit 20 executes an output process (step 55). In output processing, the processing unit 20 causes the output unit (not shown) of the insulation resistance measuring apparatus 1, and outputs the calculated insulation resistance value R _X. Thereby, when the output unit is configured by a display device, the insulation resistance value _RX is displayed on the screen of the display device. Further, when the output unit is configured with an interface circuit capable of executing data transmission to the external device, the calculated insulation resistance value _RX is output (transmitted) to the external device via the interface circuit. In this case, the external device may be a display device provided outside the insulation resistance measuring device 1 or an external memory attached to the insulation resistance measuring device 1.

Subsequently, the processing unit 20 executes a start instruction detection process for detecting whether or not the measurement start signal S1 is output from the operation unit 21 (step 56). Processing unit 20, when detecting the output of the measurement start signal S1 in this start command detection processing, by moving to step 53 to repeat the measurement (calculation) of the insulation resistance value R _X Repeat (Step 53 to Step 56 Run).

  On the other hand, the processing unit 20 completes the main routine 50 when the output of the measurement start signal S1 is not detected in the start instruction detection process. With this configuration, the operator ends the main routine 50 for the insulation resistance measuring device 1 by operating the measurement start key of the operation unit 21 while the insulation resistance measuring device 1 is starting the main routine 50. It is possible to make it.

The processing unit 20, when repeatedly measuring the insulation resistance value R _X a (calculated) (are steps 53 through repeating steps 56 run), the measurement (calculation) operation of the insulation resistance value R _X The connection disconnection detection process 70 shown in FIG. 7 is executed periodically (for example, at intervals of 1 ms). In the disconnection detection process 70, the processing unit 20 firstly performs the second detection current value of the current I in the output state of the inspection DC voltage Vm to the photovoltaic power generation unit 2 in the same manner as in the above-described step 64. The current measurement unit 18 detects the current I by measuring (calculating) Id2 based on the current data Di and comparing the second detected current value Id2 with the second threshold current value Ith2 ( It is determined whether or not the current I flows through the current measuring unit 18 (step 71).

When the processing unit 20 determines in step 71 that the current I is detected (that is, the photovoltaic power generation unit 2 is connected between the first measurement terminal 11 and the second measurement terminal 12). a) when it is determined in, to complete the disconnection detection process 70 resumes the measurement (calculation) operation of the insulation resistance value R _X.

  On the other hand, when it is determined in step 71 that the current I is not detected (that is, when it is determined that the photovoltaic power generation unit 2 is not connected between the first measurement terminal 11 and the second measurement terminal 12). The notification process is executed (step 72).

  In this notification process, for example, the processing unit 20 outputs data indicating that the solar power generation unit 2 is not connected (data indicating that the solar power generation unit 2 is not connected) to the output unit. In this case, when the output unit is configured by a display device, for example, a solar power generation unit in a connected state is displayed on the screen by displaying a mark indicating that the solar power generation unit 2 is not connected. The operator is notified that the state has shifted to the state in which 2 is not connected.

After performing this notification processing, the processing unit 20 returns to the main routine 50, to stop the measurement (calculation) Operation of the insulation resistance value R _X, (shifts to the connection detecting processing 60) to perform the connection detection process 60 (Step 73), the disconnection detection processing 70 is completed. The processing unit 20 starts detecting the presence or absence of reconnection of the photovoltaic power generation unit 2 between the first measurement terminal 11 and the second measurement terminal 12 by starting the connection detection process 60.

As described above, in the insulation resistance measuring apparatus 1, the processing unit 20 executes the connection detection process 60, and both the first measurement terminal 11 and the second measurement terminal 12 are connected to the photovoltaic power generation unit 2. and it has when it detects (solar power generation unit 2 that is connected between the first measurement terminal 11 and the second measurement terminal 12), measuring the insulation resistance value R _X photovoltaic unit 2 Execute (calculate) insulation resistance measurement processing.

Therefore, according to this insulation resistance measuring device 1, connection of the insulation resistance measuring device 1 to the photovoltaic power generation unit 2 (connection of the photovoltaic power generation unit 2 between the first measurement terminal 11 and the second measurement terminal 12 is performed. ) Is completed, the operation of the measurement start key of the operation unit 21 is performed, and even if the output of the measurement start signal S1 to the processing unit 20 is started, the processing unit 20 starts the insulation resistance measurement process. it because there is no incorrect current Ioff, it is possible to reliably prevent a situation where an incorrect insulation resistance R _X is measured (calculated) based on the Ion.

Moreover, in this insulation resistance measuring apparatus 1, in the connection detection process 60, the process part 20 performs both the above-mentioned 1st detection process and 2nd detection process in this order. Therefore, according to the insulation resistance measuring apparatus 1, for example, the first detected current value Id1 of the current I flowing due to a low voltage such as the DC voltage Vp of the photovoltaic power generation unit 2 is the first threshold current value. Not only when the photovoltaic power generation unit 2 is connected to the first measurement terminal 11 and the second measurement terminal 12 with an extremely low resistance value that is equal to or greater than Ith1, but also to a certain extent such as the inspection DC voltage Vm. second detection current value Id2 second threshold current value Ith2 more become such resistance (not about the size of inhibiting the measurement of the insulation resistance value R _X resistance value of the current I flowing due to a voltage ) for the case where the solar power generation unit 2 is connected to a first measurement terminal 11 and the second measurement terminal 12 in, it can allow the measurement of the insulation resistance value R _X.

In addition, in said insulation resistance measuring apparatus 1, although the more preferable structure that both the 1st detection process and the 2nd detection process are performed in the connection detection process 60 is employ | adopted, it is a solar power generation unit with a very low resistance value. 2 at a time that be configured to perform measurements of the insulation resistance value R _X only when connected to a first measurement terminal 11 and the second measurement terminal 12, only the execution first detection process in the connection detection processing 60 It can also be set as the structure to do. Also, enough to inhibit very low solar power generation unit 2 in resistance to matter whether or not it is connected to the first measurement terminal 11 and the second measurement terminal 12, the measurement of the insulation resistance value R _X size when good be configured to perform measurements of the insulation resistance value R _X when solar power generation unit 2 is connected to a first measurement terminal 11 and the second measurement terminal 12 is a resistance value not being, connection detection process It may be configured that only the second detection process is executed at 60.

In the insulation resistance measuring device 1 adopting any of these configurations, the operation of the measurement start key of the operation unit 21 is performed before the connection of the insulation resistance measuring device 1 to the photovoltaic power generation unit 2 is completed, and the processing unit Even if the output of the measurement start signal S1 to 20 is started, since the processing unit 20 does not start the insulation resistance measurement process, the incorrect insulation resistance value R _X based on the incorrect current values Ioff and Ion. It is possible to produce an effect that the occurrence of the situation of measuring (calculating) can be surely prevented.

Further, in this insulation resistance measuring apparatus 1, the resistance value R _{TH of} the thermistor 31 that is also the output resistance value of the voltage generation unit 13 and the resistance values R _LIM , R _DIV , and R _{DCH of the} resistors 14, 15, and 16 are expressed by the above equation. (7) at a predefined state to satisfy the calculated words, in a state in which the value of each current Ip1, Ip2 are aligned, the processing unit 20, the insulation resistance value R _X based on the equation (1) (taking measurement. Therefore, according to the insulation resistance measuring apparatus 1, even in the structure with a built-in discharge resistor 16, an incorrect current Ioff, the occurrence of a situation that an incorrect insulation resistance R _X is measured (calculated) based on Ion while reliably prevented, it is possible to accurately calculate the insulation resistance value R _X.

In the above example, the thermistor 31 is disposed between the positive output terminal 13a of the voltage generation unit 13 and the connection point between the current limiting resistor 14 and the voltage voltage dividing unit 15. As described above, a configuration in which the thermistor 31 is omitted may be employed. Although a detailed description is omitted, the equation corresponding to the equation (7) in this configuration is the following equation (9) as the equation (a) obtained by setting the resistance value R _TH in the equation (7) to zero. It becomes.
R _DCH // (R _LIM + R _DIV ) = R _LIM (9)

Therefore, even in the insulation resistance measuring apparatus 1 having the configuration in which the thermistor 31 is omitted, the resistance values R _LIM , R _DIV , and R _DCH of the resistors 14, 15, and 16 are defined in advance so as to satisfy the above equation (9). , it is possible to align the values of the currents Ip1, Ip2, even in the structure with a built-in discharge resistor 16, an incorrect current Ioff, situation that an incorrect insulation resistance _{R X} is measured (calculated) based on Ion while the occurrence reliably prevented, the processing unit 20, the insulation resistance value R _X based on the equation (1) can be accurately calculated (measured).

Further, although the insulation resistance measuring device 1 having the configuration including the discharge resistor 16 has been described as an example, the connection detection processing 60 is also performed in the insulation resistance measuring device having the configuration not including the discharge resistor 16 as described in the background art. the run, when the first measurement terminal 11 and the second measuring terminal 12 detects that it is connected both to the photovoltaic power generation unit 2, the insulation resistance value R _X photovoltaic unit 2 By performing the insulation resistance measurement process to be measured (calculated), the operation on the measurement start key of the operation unit 21 is performed before the connection of the insulation resistance measuring apparatus 1 to the photovoltaic power generation unit 2 is completed. Even if the output of the measurement start signal S1 to the processing unit 20 is started, the insulation resistance measurement process is not started, so that the incorrect current value Ioff, Ion is not correct. The occurrence of a situation that the edge resistance R _X is measured (calculated) can be reliably prevented.

  Moreover, although the solar power generation unit 2 was described as an example as an example of the measurement target 2, the insulation resistance measuring apparatus 1 outputs a DC voltage between the positive electrode and the negative electrode in addition to the solar power generation unit 2. The insulation resistance can be measured using (for example, a battery) as the measurement object 2.

1 Insulation resistance measuring device
2 Photovoltaic power generation unit 11 First measurement terminal 12 Second measurement terminal 13 Voltage generation unit 13a Positive side output terminal 13b Negative side output terminal 14 Current limiting resistor 15 Voltage dividing unit 16 Discharge resistor 17 Switching connection unit 18 Current measurement Section 20 Processing section 21 Operation section
E Grounding electrode Id1 First detection current value Id2 First detection current value Ioff, Ion Current value Ith1 First threshold current value Ith2 Second threshold current value
N negative electrode
P positive electrode

Claims (5)

A first measurement terminal connected to a grounded part in a measurement target that outputs a DC voltage from between the positive electrode and the negative electrode; a second measurement terminal connected to one of the positive electrode and the negative electrode; A current measuring unit that measures a current value of a current flowing between the first measuring terminal and the second measuring terminal; and a test DC voltage that is generated and output from between the first measuring terminal and the second measuring terminal A voltage generation unit capable of processing and a processing unit;
The processing unit executes a connection detection process for detecting connection of the first measurement terminal to the grounded portion and connection of the second measurement terminal to the one electrode, and the first measurement terminal And the current measurement unit measures the voltage generation unit in a state where the generation of the inspection DC voltage is stopped with respect to the voltage generation unit when it is detected that both of the second measurement terminals are connected. The first current value as the current value of the current is acquired, and the current value of the current measured by the current measurement unit in a state where the DC voltage for inspection is generated by the voltage generation unit An insulation resistance measurement process is performed for obtaining a second current value and calculating an insulation resistance value of the measurement object based on the obtained first and second current values and the voltage value of the test DC voltage. Insulation resistance measurement Location. The processing unit is configured to be capable of executing both the first detection process and the second detection process in the connection detection process,
In the first detection process, the current value of the current measured by the current measurement unit is acquired as a first detection current value in a state where the generation of the inspection DC voltage is stopped by the voltage generation unit. In addition, when the first detection current value is equal to or greater than the first threshold current value as compared with the first threshold current value defined in advance, the first measurement terminal and the second measurement terminal are Detect that both are connected,
In the second detection process, the current value of the current measured by the current measurement unit in a state where the DC voltage for inspection is generated by the voltage generation unit is acquired as a second detection current value and When the second detected current value is greater than or equal to the second threshold current value compared to the prescribed second threshold current value, both the first measurement terminal and the second measurement terminal are Detects connection,
The insulation resistance measuring apparatus according to claim 1, wherein the second detection process is executed when the first detection current value is less than the first threshold current value in the first detection process. The processing unit is configured to be able to execute either one of a first detection process and a second detection process in the connection detection process,
In the first detection process, the current value of the current measured by the current measurement unit is acquired as a first detection current value in a state where the generation of the inspection DC voltage is stopped by the voltage generation unit. In addition, when the first detection current value is equal to or greater than the first threshold current value as compared with the first threshold current value defined in advance, the first measurement terminal and the second measurement terminal are Detect that both are connected,
In the second detection process, the current value of the current measured by the current measurement unit in a state where the DC voltage for inspection is generated by the voltage generation unit is acquired as a second detection current value and When the second detected current value is greater than or equal to the second threshold current value compared to the prescribed second threshold current value, both the first measurement terminal and the second measurement terminal are The insulation resistance measuring apparatus according to claim 1, wherein the insulation resistance measuring apparatus detects that it is connected. The second measurement terminal is equivalently defined as a reference potential,
The voltage generation unit is configured to be able to output the generated DC voltage for inspection from between a positive output terminal and a negative output terminal,
A current limiting resistor having a resistance value R _LIM connected between the first measurement terminal and the positive output terminal;
A voltage dividing unit having a voltage dividing resistor having a resistance value R _DIV connected between the positive output terminal and the reference potential, and dividing and outputting a voltage applied to the voltage dividing resistor;
A discharge resistance having a resistance value R _DCH having one end connected to the first measurement terminal;
A switching connection portion for selectively connecting any one of the negative output terminal and the other end of the discharge resistor to the reference potential;
The resistance values R _LIM , R _DIV , and R _DCH are defined in advance so as to satisfy the following formula (a),
In the insulation resistance measurement process, the processing unit includes:
The switching connection unit is controlled to connect the other end of the discharge resistor to the reference potential, and obtain the current value Ioff as the first current value measured by the current measurement unit, and the voltage division A first measurement process for measuring a voltage value Voff of the voltage of the first measurement terminal based on the reference potential based on the voltage output from the unit;
Controlling the switching connection unit to connect the negative output terminal to the reference potential and controlling the voltage generation unit to generate the inspection DC voltage, the second current measured by the current measurement unit A second measurement process for obtaining a current value Ion as a value and measuring a voltage value Von of the voltage applied to the voltage dividing resistor based on a voltage output from the voltage dividing unit;
According to any one of claims 1 to 3 for executing a resistance calculation process of calculating the insulation resistance value R _X between the ground portion and the one electrode for said measurement target based on the following formula (b) Insulation resistance measuring device.
R _DCH // (R _LIM + R _DIV ) = R _LIM (a)
R _X = (Von−Voff−Ion × R _LIM ) / (Ion−Ioff) (b) The output resistance value of the voltage generator is defined as R _TH ,
5. The insulation resistance measuring device according to claim 4, wherein the output resistance value _RTH and the resistance values R _LIM , R _DIV , and R _DCH are defined in advance so as to satisfy the following formula (c).
R _DCH // (R _LIM + R _DIV ) = R _LIM + R _DIV // R _TH (c)

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