JP2014109561A - Insulation resistance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation resistance measuring device capable of preventing a large short-circuit current from occurring during insulation resistance measurement in various devices and automating the insulation resistance measurement.SOLUTION: A controller 11: controls a first switching circuit 1 to connect a voltage measuring part 8 to between connection terminals 5A and 5B; sets a voltage measured by the voltage measurement part 8 between measuring terminals 8A and 8B as the open circuit voltage of a solar panel; controls a second switching circuit 2 to connect a resistance 6 to between the measuring terminals 8A and 8B; calculates the internal resistance of the solar panel from a current flowing through the resistance 6 and measured by a current measurement part 9 and the open circuit voltage; and predicts a short-circuit current of the solar panel from the calculated internal resistance and the open circuit voltage.

Description

  The present invention relates to an insulation resistance measuring device for measuring insulation resistance of various devices.

A device that is a target of insulation resistance measurement includes a solar power generation device including a solar panel. An example of this solar power generation device is shown in FIG. This solar power generation device includes solar panels 110 _{1 to} 110 _n , a connection box 120, a short-circuit NFB (no fuse breaker) 130, and an interconnection NFB 140. In this solar power generation device, the DC voltage generated by the solar panels 110 _{1 to} 110 _n is added to the connection NFB 140 by the junction box 120 as one. The junction box 120 includes solar panel NFBs 121 _{1 to} 121 _n and backflow preventing rectifiers 122 _{1 to} 122 _n . The solar panel NFB 121 ₁ includes a terminal 121 ₁₁ and a terminal 121 ₁₂ , and the terminal 121 ₁₁ opens and closes with respect to the terminal 121 ₁₂ , that is, the solar panel NFB 121 ₁ is turned on and off, and the output of the solar panel 110 ₁ . Is switched between connection to NFB 140 for interconnection and disconnection.

Similarly, NFB121 ₂ for solar panels provided with terminal 121 ₂₁ and terminal 121 ₂₂ ,..., NFB121 _n for solar panel provided with terminal 121 _n1 and terminal 121 _n2 are turned on and off, and solar panel 110 is provided. ₂ ,..., 110 _n are switched between connecting and disconnecting to the interconnection NFB 140.

The interconnection NFB 140 includes a terminal 141 and a terminal 142. The connection NFB 140 switches whether to send the output of the connection box 120, that is, the outputs from the solar panels 110 _{2 to} 110 _n, to the subsequent DC / AC converter by switching on and off.

  The short circuit NFB 130 includes a terminal 131 and a terminal 132. Then, the short-circuit NFB 130 short-circuits the output of the solar panel to be measured, and switches whether to connect the megger (insulation resistance meter) 210 to the short-circuited output. That is, the short-circuit NFB 130 is used at the time of insulation measurement.

When the person in charge performs insulation measurement of the solar panels 110 _{1 to} 110 _n of such a solar power generation apparatus, a predetermined procedure using the Megar 210 is determined in advance. That is, even if the solar panels 110 _{1 to} 110 _n are disconnected from the electric circuit, an open circuit voltage is generated as long as sunlight is received, so a predetermined procedure is required. This predetermined procedure is
Procedure a. Step for cutting all NFB 121 _{1 to} 121 _n for solar panel, NFB 130 for short circuit, and NFB 140 for interconnection b. Procedure for short-circuiting between the terminals 131 of the short-circuiting NFB 130 to make the terminal 131 a short-circuited end c. NFB for short-circuiting to NFB for solar panel of solar panel to be measured
Procedure for connecting 0 open end (terminal 132) d. One measurement terminal of the megger 210 is connected to the short-circuit end of the short-circuit NFB 130,
Procedure for grounding the other measurement terminal e. Procedure for inserting NFB for solar panel of solar panel to be measured f. Procedure for inserting NFB 130 for short circuit g. The megger 210 measures the insulation resistance.

  These procedures a to g are performed by a person in charge, but due to the complexity of the procedure, there are the following devices (for example, see Patent Document 1). This device is permanently installed in the power conditioner of the solar power generation device. And a high voltage power supply is temporarily added to a solar cell panel, and insulation resistance is measured. As a result, the insulation resistance is automatically measured.

JP-A-8-15345

However, when the person in charge performs the previous procedure a to procedure g, there is the following problem. It is necessary to connect the junction box 120 and the short-circuiting NFB 130 for each measurement of the insulation resistance of the solar panels 110 _{1 to} 110 _n of the solar power generation apparatus and to take into account the measurement procedure (procedure a to procedure g). In this case, the wrong measurement procedure, for example when the measurement object is a solar panel 110 _1, the off forgotten the NFB, if there in a state where another solar panel is connected to the solar panels 110 ₁ There is a possibility of electric shock when a large short-circuit current flows.

Moreover, the apparatus which measures an insulation resistance automatically is permanently installed in the power conditioner of a solar power generation device. It can be said that installing an apparatus for each of the solar panels 110 _{1 to} 110 _n is inefficient in terms of measurement frequency and cost.

  An object of the present invention is to provide an insulation resistance measuring apparatus that solves the above-described problems, prevents a large short-circuit current from occurring when measuring the insulation resistance of various apparatuses, and automates the insulation resistance measurement.

  In order to solve the above-mentioned problem, the invention of claim 1 is an insulation resistance measuring apparatus for measuring an insulation resistance of a measurement object that generates a voltage, and each connection used by being connected to an output of the measurement object. A voltage measurement unit that measures a voltage between the connection terminals, a first switch circuit that switches whether the voltage measurement unit is connected between the connection terminals, and a resistor that is connected between the connection terminals A current measuring unit that measures a current flowing through the resistor; a second switch circuit that switches whether the resistor is connected between the connection terminals; and the voltage measuring unit that controls the first switch circuit to The voltage measured between the connection terminals and measured by the voltage measurement unit between the connection terminals is set as the open voltage of the measurement object, and the second switch circuit is controlled to connect the resistor between the connection terminals. Contact And calculating the internal resistance of the measurement target from the current flowing through the resistance measured by the current measuring unit and the open circuit voltage, and predicting the short-circuit current of the measurement target from the internal resistance and the open circuit voltage It is an insulation resistance measuring apparatus characterized by including a part.

  In the first aspect of the invention, the control unit controls the first switch circuit to connect the voltage measuring unit between the connection terminals. Then, a control part makes the voltage which the voltage measurement part measured between each connection terminal the open circuit voltage of a measuring object. Thereafter, the control unit controls the second switch circuit to connect the resistor between the connection terminals. And a control part calculates the internal resistance of a measuring object from the electric current which flows through resistance which the current measurement part measured, and an open circuit voltage. Furthermore, a control part estimates the short circuit current of a measuring object from internal resistance and an open circuit voltage.

  According to a second aspect of the present invention, in the insulation resistance measuring apparatus according to the first aspect, the control unit compares a specified value stored in advance with a short-circuit current of the measurement target, and the short-circuit current is defined.

If the value is greater than or equal to the value, it is output that measurement of insulation resistance cannot be measured.

  According to a third aspect of the present invention, in the insulation resistance measuring apparatus according to the second aspect, a short circuit that short-circuits between the connection terminals, and a third switch circuit that switches whether the short circuit is connected between the connection terminals. And a voltage generator for applying a voltage to the short circuit, wherein the current measurement unit measures a current flowing between the voltage generator and the short circuit, and the control unit defines the short circuit current. When smaller than the value, the third switch is controlled to connect the short circuit between the connection terminals, the voltage generator is controlled, the voltage is applied to the short circuit, and the current measurement unit measures The current is the leakage current of the measurement object, and the insulation resistance of the measurement object is calculated from the open circuit voltage and the leakage current.

  According to the first aspect of the present invention, since the short-circuit current of the measurement target is automatically predicted from the internal resistance of the measurement target and the open circuit voltage, it is possible to measure the safe insulation resistance of the measurement target.

  According to the invention of claim 2, when the short-circuit current is larger than the specified value, the measurement result of the insulation resistance is not output. Therefore, when measuring the insulation resistance of the measurement object, for example, another voltage is generated for the measurement object. The person in charge of the measurement can be notified of the state in which the device is connected.

  According to the invention of claim 3, the short circuit, the third switch circuit, and the voltage generator are provided, and the control unit controls the third switch circuit and the voltage generator, whereby the insulation resistance to be measured is measured. Can be measured automatically.

It is a figure which shows an example of the insulation resistance measuring apparatus by Embodiment 1 of this invention. It is a block diagram which shows an example of a control part. It is a flowchart which shows an example of a measurement process. It is explanatory drawing explaining prediction of a short circuit current, FIG.4 (a) is a figure which shows the measurement of an open circuit voltage, FIG.4 (b) is a figure which shows the measurement of an electric current, FIG.4 (c) is prediction of a short circuit current. FIG. It is explanatory drawing explaining an insulation measurement. It is explanatory drawing explaining the insulation measurement by Embodiment 2. FIG. It is a figure explaining the insulation resistance measurement of a solar panel.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. In each embodiment, components that are the same as or the same as those in FIG. 7 described above are denoted by the same reference numerals, and description thereof is omitted.

(Embodiment 1)
An insulation resistance measuring apparatus according to this embodiment is shown in FIG. This insulation resistance measuring device is for measuring the insulation resistance of a solar panel installed in a solar power generation device. The insulation resistance measuring device includes a first switch circuit 1, a second switch circuit 2, and a third switch circuit 3. In addition, the insulation resistance measuring apparatus includes a protection circuit 4, connection terminals 5 </ b> A and 5 </ b> B, a resistor 6, and a current transformer 7. Furthermore, the insulation resistance measuring device includes a voltage measuring unit 8, a current measuring unit 9, a voltage generating unit 10, and a control unit 11. In FIG. 1, signal-related wiring is indicated by broken lines in order to make the drawing easier to see.

  The connection terminals 5A and 5B are portions connected by a person in charge of measurement to the solar panel NFB of the solar panel to be measured. The protection circuit 4 includes a fuse 4A provided at the connection terminal 5A and a fuse 4B provided at the connection terminal 5B. When the connection terminals 5A and 5B are connected to the solar panel NFB of the solar panel to be measured, the protection circuit 4 prevents an excessive current from flowing. Note that NFB may be used instead of the fuses 4A and 4B.

  The first switch circuit 1 switches whether the voltage measuring unit 8 is connected between the wiring 12A on the connection terminal 5A side and the wiring 12B on the connection terminal 5B side. For this purpose, the first switch circuit 1 includes first switches 1A and 1B. The first switch 1A is connected between the wiring 12A and the measurement terminal 8A of the voltage measurement unit 8, and the first switch 1B is connected between the wiring 12B and the measurement terminal 8B of the voltage measurement unit 8. The first switch circuit 1 opens / closes, that is, turns on / off the first switches 1A and 1B under the control of the control unit 11.

  The voltage measurement unit 8 includes a measurement terminal 8A and a measurement terminal 8B, and measures a voltage between the measurement terminal 8A and the measurement terminal 8B, that is, an output voltage of the solar panel. Then, the voltage measurement unit 8 sends the measurement voltage to the control unit 11.

  The second switch circuit 2 switches whether to connect a series circuit of the resistor 6 and the current transformer 7 between the wiring 12A on the connection terminal 5A side and the wiring 12B on the connection terminal 5B side. For this purpose, the second switch circuit 2 includes second switches 2A and 2B. The second switch 2A is connected between the resistor 6 and the wiring 12A, and the second switch 2B is connected between the current transformer 7 and the wiring 12B. The second switch circuit 2 opens and closes the second switches 2A and 2B under the control of the control unit 11.

  A series circuit of the resistor 6 and the current transformer 7 is used when calculating the internal resistance of the solar panel. For this purpose, the resistor 6 and the current transformer 7 are connected in series, the current transformer 7 detects a current corresponding to the current flowing through the resistor 6, and outputs the detected current to the current measuring unit 9. The resistor 6 has a known resistance value that is sufficiently larger than the internal resistance of the solar panel. This prevents a large current from flowing through the resistor 6.

  The current measuring unit 9 measures the current flowing through the current transformer 7 based on the detected current from the current transformer 7. Then, the current measurement unit 9 outputs the measurement current to the control unit 11.

  The third switch circuit 3 switches whether to short-circuit between the wiring 12A on the connection terminal 5A side and the wiring 12B on the connection terminal 5B side. For this purpose, the third switch circuit 3 includes third switches 3A and 3B. The third switch 3A and the third switch 3B are connected by a short-circuit line 12C. The short circuit line 12 </ b> C forms a short circuit when measuring the insulation resistance of the solar panel. That is, the third switch 3A is connected between the wiring 12A and the short-circuit line 12C, and the third switch 3B is connected between the wiring 12B and the short-circuit line 12C. The third switch circuit 3 opens and closes the third switches 3A and 3B under the control of the control unit 11.

  The voltage generator 10 is used when measuring the insulation resistance of the solar panel. For this purpose, the wiring 12D connected to the output terminal 10A of the voltage generator 10 is connected to the short circuit line 12C through the current transformer 7, and the output terminal 10B is connected to the ground. When measuring the insulation resistance of the solar panel, the voltage generator 10 applies a predetermined voltage, which is a high voltage, between the short-circuit line 12 </ b> C and the ground under the control of the controller 11. At this time, when a leakage current is generated by the solar panel, the leakage current flows through the wiring 12D and further flows through the current transformer 7. Then, the current transformer 7 outputs a current corresponding to the current flowing through the wiring 12 </ b> D to the current measuring unit 9.

  The control part 11 performs control regarding an insulation resistance measuring apparatus. For this purpose, as shown in FIG. 2, for example, the control unit 11 includes an input device 11A, a display device 11B, a control circuit 11C, an interface 11D, and a storage device 11E. The input device 11A includes a switch for inputting an instruction to start measurement of insulation resistance. The display device 11B is a device such as a liquid crystal panel that displays a control result or a calculation result by the control circuit 11C. The interface 11D is a circuit for connecting the first switch circuit 1 to the third switch circuit 3, the voltage measurement unit 8, the current measurement unit 9, and the voltage generation unit 10 to the control circuit 11C. The storage device 11E stores measurement data and the like. In addition, the storage device 11E stores a program necessary for the control circuit 11C in advance.

  The control circuit 11C executes a program stored in the storage device 11E. The program executed by the control circuit 11C includes a measurement process for measuring the insulation resistance of the solar panel. When a start instruction is input to the input device 11A, the control circuit 11C starts, for example, the measurement process illustrated in FIG. When the measurement process is started, the control circuit 11C controls the first switch circuit 1 to the third switch circuit 3, closes the first switches 1A and 1B, and sets the second switches 2A and 2B and the third switches 3A and 3B. Open (step S1). That is, the first switches 1A and 1B are turned on, and the second switches 2A and 2B and the third switches 3A and 3B are turned off. By step S1, it becomes a circuit structure by which the voltage measurement part 8 is connected between the connection terminal 5A side and the connection terminal 5B side.

  When step S1 ends, the control circuit 11C obtains the open voltage of the solar panel via the interface 11D by the measured voltage from the voltage measuring unit 8 (step S2). That is, the control circuit 11C measures the open voltage of the solar panel in step S2. The open circuit voltage measured in step S <b> 2 is a voltage of the measurement object 110, for example, as shown in FIG. The measurement object 110 corresponds to a solar panel.

  When step S2 ends, the control circuit 11C controls the first switch circuit 1 to the third switch circuit 3, opens the first switches 1A and 1B, closes the second switches 2A and 2B, and sets the third switch 3A, 3B is opened (step S3). That is, the first switches 1A and 1B are turned off, the second switches 2A and 2B are turned on, and the third switches 3A and 3B are turned off. In step S3, a series circuit of the resistor 6 and the current transformer 7 is connected between the connection terminal 5A side and the connection terminal 5B side, and the current transformer 7 detects a current flowing through the resistor 6. . Then, the current measuring unit 9 measures the current value based on the detected current.

When step S3 ends, the control circuit 11C obtains a current when the resistor 6 is connected via the interface 11D by the measured current from the current measuring unit 9 (step S4). That is, in step S4, the control circuit 11C measures the current when the resistor 6 is connected. Thereafter, the control circuit 11C opens the second switches 2A and 2B (step S5), and the internal voltage of the object to be measured is determined from the open voltage measured in step S2 and the current when the resistor 6 is connected measured in step S4. Resistance is calculated (step S6). In step S6, for example, as shown in FIG. 4B, when a resistance 6 having a resistance value R is connected to the measurement object 110, the measurement current I is
I = V / (R ₀ + R)
It becomes. From this formula:
R ₀ = (V / I) −R
It becomes. The control circuit 11C obtains the resistance value _R0 of the internal resistance using this equation.

When step S6 ends, the control circuit 11C predicts a short-circuit current due to the measurement target from the open circuit voltage measured in step S2 and the internal resistance calculated in step S6 (step S7). In step S7, for example, as shown in FIG. 4C, the short-circuit current value I ₀ is obtained from the voltage value V of the open circuit voltage obtained in step S2 and the resistance value R ₀ of the internal resistance obtained in step S6. Is
I ₀ = V / R ₀
It becomes. The control circuit 11C has used this equation to obtain the current value I ₀ of the short-circuit current due to the measurement target 110.

  When step S7 ends, the control circuit 11C compares the specified value stored in advance in the storage device 11E with the current value of the short circuit current (step S8), and determines whether the current value of the short circuit current is smaller than the specified value. It is determined whether or not (step S9). The specified value in step S8 is a value based on the current value of the short-circuit current per solar panel, for example, the margin value is added to the value of the short-circuit current per solar panel.

  When the current value of the short-circuit current is smaller than the specified value in step S9, the control circuit 11C controls the first switch circuit 1 to the third switch circuit 3 so that the first switch 1A, 1B and the second switch 2A, 2B. And the third switches 3A and 3B are closed (step S10). That is, the first switches 1A and 1B and the second switches 2A and 2B are turned off, and the third switches 3A and 3B are turned on. By step S10, the connection terminal 5A side and the connection terminal 5B side are short-circuited by the short-circuit line 12C, and the voltage generator 10 is connected between the short-circuit line 12C and the ground. Thereby, it becomes a circuit structure by which the voltage generation part 10 is connected between a solar panel and earth | ground.

When step S10 ends, the control circuit 11C controls the voltage generator 10 to apply a known voltage between the short-circuit line 12C and the ground, that is, between the solar panel and the ground (step S11). In step S11, for example, applying a voltage of the voltage value _{V 1} between the measuring object 110 and ground.
After step S11, when a leakage current is generated by the measurement object 110, the current transformer 7 detects this current. Then, the control circuit 11C obtains the leakage current measured by the current measuring unit 9 based on the detected current via the interface 11D (step S12). That is, the control circuit 11C measures the leakage current of the measurement object 110 in step S12.

  When step S11 ends, the control circuit 11C controls the first switch circuit 1 to the third switch circuit 3 to open the first switches 1A and 1B, the second switches 2A and 2B, and the third switches 3A and 3B. (Step S13). That is, the first switches 1A and 1B, the second switches 2A and 2B, and the third switches 3A and 3B are all turned off.

After step S13, the control circuit 11C calculates the insulation resistance of the measurement target (solar panel) from the voltage value applied by the voltage generator 10 in step S11 and the leakage current measured in step S12 (step S13). S14). For example, when the voltage generating unit 10 plus the voltage of the voltage value V ₁ in solar panels 110 _1, the leakage current of a current value I ₁ is generated, the insulation resistance R ₁ is
R ₁ = V ₁ / I ₁
It becomes. The control circuit 11C uses the equation in step S14, to calculate the insulation resistance _{R 1} of the solar panels 110 _1.

  When step S14 ends, the control circuit 11C outputs the calculated resistance value of the insulation resistance (step S15). In this embodiment, the control circuit 11C displays the calculated resistance value of the insulation resistance on the display device 11B. When step S15 ends, the control circuit 11C ends the measurement process.

  On the other hand, if the current value of the short circuit current is greater than or equal to the specified value in step S9, the control circuit 11C outputs a signal indicating that measurement is not possible (step S16). In this embodiment, the control circuit 11C causes the display device 11B to display a message indicating “measuring impossible”. The control circuit 11C ends the measurement process after step S16.

Next, the insulation resistance measurement using the insulation resistance measurement device according to this embodiment will be described by taking as an example a solar power generation device including the solar panels 110 _{1 to} 110 _n and the junction box 120 similar to those in FIG. If the measurement object is a solar panel 110 _1, personnel performing insulation measurement, cut and NFB121 ₁ ~121 _n solar panel housed in a junction box 120, and interconnection for NFB140, 5 as shown, the connection terminal 5A of the insulation resistance measuring device, 5B and respectively connected to the terminals _{121 11} for solar panels NFB121 _1. In FIG. 5, only the solar panels 110 ₁ and 110 ₂ and their peripheral parts are shown, and the others are omitted.

Thereafter, the person in charge operates the input device 11A of the control unit 11 of the insulation resistance measuring device to input a start instruction. Thus, the insulation resistance measuring device to start the measurement process to measure the insulation resistance of the solar panels 110 _1. In this case, even if the two or more NFB closes including solar panels NFB121 ₁ for solar panels 110 _1, that is, another solar panel is connected to the solar panels 110 ₁ Even in this state, the display device 11B of the insulation resistance measuring device displays the message “measuring impossible” in steps S1 to S9 and step S16 of the measurement process. Thus, the insulation resistance measuring device, that another solar panel is connected to the solar panels 110 ₁ informs the person in charge. Then, the insulation resistance measuring device is to short-circuit the output of the solar panels 110 ₁ of adding a voltage from the voltage generating unit 10 stops the measurement of the insulation resistance.

On the other hand, when the solar panels 110 ₁ is alone, the insulation resistance measuring device, the processing of steps S10~S15 following step S1-S9, measuring the insulation resistance by short-circuiting the output of the solar panels 110 ₁ Then, the resistance value of the insulation resistance is displayed on the display device 11B.

  Thus, according to this embodiment, when measuring the insulation resistance, if another solar panel is connected to the solar panel to be measured, the insulation resistance measuring device cannot automatically measure. Output, enabling safe and easy measurement of insulation resistance. Further, according to this embodiment, there is no need to install an insulation resistance measuring device permanently from the viewpoint of measurement frequency, and the measurement method using the insulation resistance measuring device is excellent in portability and advantageous in cost. Furthermore, according to this embodiment, if there is a need to take the trend of insulation resistance (the tendency of resistance value), the insulation resistance measuring device is permanently installed, the short-circuit current is predicted at a fixed time, It is possible to measure the insulation resistance after confirming that there is no problem.

In this embodiment, the connection terminals 5A of the insulation resistance measuring device has been connected 5B to terminal _{121 11} for solar panels NFB121 _1, connected to a terminal _{121 12} for solar panels NFB121 ₁ terminals 5A, 5B connect the by turning on NFB121 ₁ for solar panels, it is of course possible to measure the insulation resistance by insulation resistance measuring device.

(Embodiment 2)
In this embodiment, the insulation resistance measurement using the insulation resistance measuring apparatus according to Embodiment 1 is performed as follows. Also in this embodiment, a solar power generation apparatus including solar panels 110 _{1 to} 110 _n and a junction box 120 similar to those in FIG. 7 is taken as an example.

In this embodiment, when the measurement target is the solar panel 110 _n , the person in charge of insulation measurement uses the solar panel NFBs 121 _{1 to} 121 _n and the interconnection NFB 140 stored in the connection box 120. As shown in FIG. 6, the connection terminals 5A and 5B of the insulation resistance measuring device are connected to the terminal 141 of the interconnection NFB 140, respectively. In FIG. 6, only the solar panel 110 _n and the interconnection NFB 140 and their peripheral parts are shown, and the others are omitted.

Thereafter, the person in charge closes the solar panel NFB 121 _n and inputs a start instruction to the insulation resistance measuring apparatus. Thus, the insulation resistance measuring device to start the measurement process to measure the insulation resistance of the solar panel 110 _n. At this time, even if another solar panel is connected to the solar panel 110 _n , the insulation resistance measuring device is “not measurable” by steps S1 to S9 and step S16 of the measurement process. Display a message. Thus, the insulation resistance measuring device, that another solar panel is connected to the solar panel 110 _n, inform the person in charge. Then, the insulation resistance measuring device stops measuring the insulation resistance.

On the other hand, when the solar panel 110 _n is alone, the insulation resistance measuring device measures the insulation resistance by short-circuiting the output of the solar panel 110 _{n in} steps S10 to S15, and determines the resistance value of the insulation resistance. indicate.

  Thus, according to this embodiment, the connection terminals 5A and 5B of the insulation resistance measuring device are connected to the terminal 141 of the interconnection NFB 140, respectively, and the insulation resistance is measured. Therefore, the solar panel to be measured is changed. This eliminates the need to remove and reconnect the connection terminals 5A and 5B each time, thereby enabling efficient insulation resistance measurement.

DESCRIPTION OF SYMBOLS 1 1st switch circuit 2 2nd switch circuit 3 3rd switch circuit 4 Protection circuit 5A, 5B Connection terminal 6 Resistance 7 Current transformer 8 Voltage measurement part 8A, 8B Measurement terminal 9 Current measurement part 10 Voltage generation part 10A, 10B Output Terminal 11 Control unit 11A Input device 11B Display device 11C Control circuit 11D Interface 11E Storage devices 12A, 12B, 12D Wiring 12C Short circuit (short circuit)

Claims (3)

An insulation resistance measuring device for measuring an insulation resistance of a measurement target that generates a voltage,
Each connection terminal used by being connected to the output of the measurement object,
A voltage measuring unit for measuring a voltage between the connection terminals;
A first switch circuit for switching whether to connect the voltage measuring unit between the connection terminals;
A resistor connected between the connection terminals;
A current measuring unit for measuring a current flowing through the resistor;
A second switch circuit for switching whether to connect the resistor between the connection terminals;
The first switch circuit is controlled to connect the voltage measurement unit between the connection terminals, and the voltage measured by the voltage measurement unit between the connection terminals is set as the open voltage of the measurement target, and the second The switch circuit is controlled to connect the resistor between the connection terminals, and the internal resistance of the measurement target is calculated from the current flowing through the resistor measured by the current measuring unit and the open voltage, and the internal resistance And a controller that predicts the short-circuit current of the measurement object from the open circuit voltage,
An insulation resistance measuring device comprising: The control unit compares a predetermined value stored in advance with the short-circuit current to be measured, and outputs an inability to measure insulation resistance when the short-circuit current is equal to or greater than a predetermined value.
The insulation resistance measuring apparatus according to claim 1. A short circuit for short-circuiting between the connection terminals;
A third switch circuit for switching whether to connect the short circuit between the connection terminals;
A voltage generator for applying a voltage to the short circuit;
With
The current measuring unit measures a current flowing between the voltage generating unit and the short circuit,
When the short circuit current is smaller than a specified value, the control unit controls the third switch to connect the short circuit between the connection terminals, and controls the voltage generation unit to control the voltage to the short circuit. In addition, the current measured by the current measuring unit is the leakage current of the measurement target, and the insulation resistance of the measurement target is calculated from the open-circuit voltage and the leakage current.
The insulation resistance measuring apparatus according to claim 2.

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