KR20070107453A - Insulation monitoring system - Google Patents

Abstract

An insulation monitoring system is provided to detect accurately a leakage current or an insulating resistance value of voltage supplied from a transformer regardless of a change of operational conditions of a VVVF(Variable Voltage Variable Frequency) like an inverter. An insulation monitoring system comprises followings. A voltage detector(311) is installed to detect a voltage component supplying to loads like a motor and to transform it to an uniform size. A zero-phase current transformer is installed to detect a leakage current of electric wire path. A current detector(331) is installed to extract frequency component by transforming the detected leakage current component to a voltage component. An analog/digital converter(32) is installed to transform an analog component of output values from the voltage detector and the current detector into a digital component. A programmable logic controller(35) and an input/output parts(361,362) are installed.

Description

Insulation Monitoring System

1 is a circuit diagram of a conventional insulation monitoring system.

2 is a circuit diagram of a conventional insulation monitoring device.

Figure 3 is a circuit diagram of a first embodiment of the insulation monitoring system of the present invention.

Figure 4 is a circuit diagram of a second embodiment of the insulation monitoring system of the present invention.

5 is a circuit diagram of a third embodiment of an insulation monitoring system of the present invention.

6 is a circuit diagram of a fourth embodiment of an insulation monitoring system of the present invention.

7 is a block diagram of a first embodiment of the insulation monitoring apparatus used in FIGS.

8 is a detailed circuit diagram of a first embodiment of the insulation monitoring apparatus used in FIGS.

9 is a block diagram of a second embodiment of the insulation monitoring device used in FIGS.

FIG. 10 is a detailed circuit diagram of a second embodiment of an insulation monitoring apparatus used in FIGS. 3 to 6. FIG.

FIG. 11 is a flowchart of operation of the first embodiment of FIG. 7;

12 is a flowchart of operation of the second embodiment of FIG.

<Explanation of symbols for main parts of the drawings>

8: VVVF 10: Video Current Transformer

20, 30: insulation monitoring device 12, 13, 14: voltage detection means

31: voltage detector 32: A / D converter

33: current detector 34: zero cross portion

35: operation control unit 36: input and output unit

38: communication unit

The present invention relates to an insulation monitoring system. More specifically, the present invention relates to an insulation monitoring system that monitors an insulation state of an electric line including a load in an electric line for supplying power to a load by using a power equipment of a VVVF such as an inverter.

In a cable line that supplies power to a load by using a power equipment such as a conventional inverter, a method of monitoring the insulation state of a wire line including a load includes a video current component flowing through the ground line in the grounded ground system of the secondary side of the transformer. There is a method of detecting or detecting a leakage current flowing between the earth to the cable line. In a non-grounded system in which the secondary side of the transformer is not grounded, there are many methods of detecting a video voltage. Due to the high carrier frequency, the leakage current to the ground increases, so that a leakage current with a larger leakage current than that of the insulation state is often detected.

In order to solve this problem, an insulation monitoring system such as FIGS. 1 and 2 is disclosed in Japanese Laid-Open Patent Publication No. 2006-20483. This conventional technique will be described in more detail.

As shown in FIG. 1, a power system in which commercial AC power is supplied to a wire line 3 through a transformer 1 and a switch 2 for converting a voltage is VVVF (Variable Voltage Variable Frequency: VVVF). A load 4 such as a motor is controlled through an inverter 8 such as "".

In FIG. 1, the secondary side of the transformer 1 is wired with a Y connection, and the neutral point of the wire connection is grounded to the second type ground 6 through the ground wire 5. Insulation state between VVVF 8 and transformer 1 is good, and insulation state is poor on output terminal of VVVF 8 and R phase of load 4, that is, insulation resistance 9 is low between R phase and earth. The leakage current Io flows through the ground through the insulation resistance 9. The leakage current (Io) component is detected by the image current transformer 10 and configured by a system for detecting by the insulation monitoring device 20 configured as shown in FIG.

The leakage current Io component detected by the image current transformer 10 removes a component having a frequency higher than the commercial frequency from the low pass filter 21 and LPF, and amplifies the leakage current Io. When the output of the amplifier 22 is filtered by the band pass filter 23 and BPF and is larger than the leakage current alarm value preset through the level detector 24 and the operation determination processor 25, the output processor 26 is used. Alarm output through. However, this system has the following problems.

The operating operation frequency and output voltage of the VVVF 8 such as the inverter depend on the operating conditions of the load 4 such as the motor, and the component of the leakage current Io leaked to the earth through the insulation resistance 9 is also VVVF ( 8) The leakage current value detected through the image current transformer 10 also varies depending on the operating operation conditions of the VVVF (8) even though the insulation resistance (9) value is constant. Without reflecting the operating condition of (8), only the leakage current value detected through the image current transformer 10 cannot accurately monitor the insulation state of the cable line including the load 4. For example, when the insulation resistance 9 is 10Kohm, the leakage current leaked to the earth ground 7 through the insulation resistance 9 when the VVVF 8 has a line output voltage of 380V and an operating frequency of 60 Hz. The value is 220mA as follows.

When VVVF 8 is 190V between the line output voltage and the operating frequency is 30Hz, the leakage current leakage through the insulation resistor 9 to the earth ground 7 is 110mA as follows.

If the alarm set value of the insulation monitoring device 20 is 150 mA, when the VVVF 8 is operated at 60 Hz and 380 V while the insulation state remains the same as described above, an alarm is generated and VVVF (8 ) Is inaccurate measurement, such as no alarm when 30Hz, 190V operating.

Therefore, there has been a demand for an insulation monitoring system capable of accurately monitoring the insulation state of the electric line including the load 4 even when the operating conditions of the VVVF 8 such as an inverter for supplying power to the load 4 such as a motor are changed. .

The present invention has been made to solve the problems of the prior art, an object of the present invention is to provide an insulation monitoring system that can accurately monitor the insulation state of the cable line including the load even if the operating operating conditions of the VVVF, such as an inverter It's there.

It is still another object of the present invention to provide an insulation monitoring system capable of remotely controlling the display, alarm alarm output, and communication unit by calculating the insulation resistance of the voltage of the commercial alternating frequency between the cable line and the earth.

Insulation monitoring system of the present invention for achieving the object of the present invention includes a voltage detection unit for detecting the voltage component supplied to the load, such as a motor and converting it into a constant magnitude; An image current transformer for detecting a leakage current to a wire supplied to a load such as a motor, and a current detection unit for converting the leakage current component detected by the image current transformer into a voltage component to extract only a frequency component; An analog / digital converter for converting an analog component of the output value of the voltage detector and the output value of the current detector to a digital component; An operation control unit for reading and outputting various data and having an operation and control function; And an input / output unit for inputting and displaying various data.

The current detector includes an image current transformer for detecting a leakage current in a line supplied to a load such as a motor, a current / voltage converter for converting the leakage current component detected by the image current transformer into a voltage component, and the current / It consists of a current filter for removing a frequency component above a certain frequency or extracting only a frequency component of a predetermined frequency band from the leakage current component converted by the voltage converter, and an amplifier for amplifying the leakage current component detected by the current filter unit. .

In addition, the present invention is a device for monitoring the insulation state of the load circuit, such as a motor driven by VVVF having a function of controlling the voltage and frequency,

A voltage detector for detecting a voltage component supplied to a load such as a motor and converting the same into a predetermined magnitude; A zero cross section having a function of comparing and detecting zero points of the voltage components extracted by the voltage detecting section, a counter section for detecting a frequency of the component detected by the zero cross section;

An image current transformer for detecting a leakage current to a wire supplied to a load such as a motor, a current / voltage conversion unit for converting the leakage current component detected by the image current transformer into a voltage component, and the current / voltage conversion unit A current detector comprising an amplifier for amplifying the converted leakage current component, and a current filter for removing a frequency component above a predetermined frequency or extracting only a frequency component of a predetermined frequency band from the leakage current component amplified by the amplifier;

An analog / digital converter for converting an analog component of the output value of the voltage detector and the output value of the current detector to a digital component; An operation control unit for reading and outputting various data and having an operation and control function; And an input / output unit having a function of inputting, displaying or alarming various data, and detecting the leakage current component detected by the image current transformer, the current / voltage converter, the amplifier, and the current filter unit. Comparing with the voltage component detected by the means and the voltage filter unit is characterized in that the conversion to the leakage current component or the insulation resistance to the voltage of the commercial frequency component of 50Hz or 60Hz.

In addition, the insulation monitoring system of the present invention preferably further comprises a communication unit for remote monitoring from the outside.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 3 is a circuit diagram of a first embodiment of the insulation monitoring system of the present invention, Figure 4 is a circuit diagram of a second embodiment of the insulation monitoring system of the present invention, Figure 5 is a circuit of a third embodiment of the insulation monitoring system of the present invention. 6 is a circuit diagram of a fourth embodiment of an insulation monitoring system of the present invention.

FIG. 7 is a block diagram of the first embodiment of the insulation monitoring apparatus used in FIGS. 3 to 6, and FIG. 8 is a detailed circuit diagram of the first embodiment of the insulation monitoring apparatus used in FIGS. 9 is a block diagram of a second embodiment of the insulation monitoring device used in FIGS. 3 to 6, and FIG. 10 is a detailed circuit diagram of a second embodiment of the insulation monitoring device used in FIGS.

FIG. 11 is an operation flowchart of the first embodiment of FIG. 7, and FIG. 12 is an operation flowchart of the second embodiment of FIG. 9.

3 shows that the secondary connection of the transformer 1 is Y and the neutral point is grounded, and the phase voltage between the grounds is detected by using the voltage detecting means 12 for detecting the voltage component of the wire line 11. 4 is an embodiment similar to that of FIG. 3, but using voltage detecting means 12 and 13 to detect the line voltage between the voltage components of the line 11 and FIG. 5. Is the embodiment in which the secondary connection of the transformer 1 is delta Δ and the non-grounding method, and FIG. 6 is an embodiment in which the secondary connection of the transformer 1 is delta Δ, but the T phase is grounded once. It is an embodiment in which the voltage of all three phases is detected using three detection means 12,13,14. 3 to 6 described above, four embodiments are shown, but various embodiments are different depending on the type of the secondary connection of the transformer 1 and which phase of the three phases of the voltage detecting means is detected. can do.

7 to 9 are detailed circuit diagrams of the insulation monitoring apparatus 30 of FIGS. 3 to 6. 10 and 11 are flowcharts for describing an operation of the insulation monitoring apparatus 30 of FIGS. 7 and 9.

3, 7, and 10, which are embodiments of the present invention, will be described first.

In FIG. 3, 1 is a transformer for converting a voltage, and supplies electric power to the wire path 3 through the switch 2. 5 is a ground wire for connecting the neutral point of the transformer 1 to ground 6 for safety. In general, the transformer is grounded with two types of grounds (6), and the load side is provided with three kinds of grounds (7). In the future, there is a high possibility that it will be changed to the common ground without dividing the 2 types and 3 types of ground. On the other hand, in the state that power is supplied to the load 4 such as a motor through the switch 2 and the cable line 3 and the VVVF 8 such as an inverter, the line 11 including the load 4 and the ground When the insulation deteriorates, the insulation resistance value of the insulation resistance 9 becomes low, and the leakage current Io component flows to the earth ground 7 through this insulation resistance 9. The state of the insulation resistance 9 can be known by knowing the leakage current Io component and the ground-to-ground voltage value of the wire path 3a.

In order to detect the above leakage current (Io) component, it is detected by an image current transformer 10 such as ZCT, and voltage detection means 12 is used to detect the ground voltage of the line 11. The voltage detection means 12 detects the phase voltage between the cable line 11 and the ground, and the secondary side of the current transformer 10 and the voltage detection means 12 are described in detail in FIG. It is connected to the insulation monitoring device 30 shown.

7 is a block diagram of a first embodiment of the insulation monitoring apparatus used in FIGS.

The insulation monitoring device 30 of the present invention includes: a voltage detector 31 which detects a voltage component supplied to a load such as a motor and converts the voltage component into a predetermined magnitude; An image current transformer for detecting a leakage current to a wire supplied to a load such as a motor, and a current detector 33 for converting the leakage current component detected by the image current transformer into a voltage component to extract only a frequency component;

An analog / digital converter 32 for converting an analog component of the output value of the voltage detector 31 and the output value of the current detector 33 into a digital component; An operation control unit 35 for reading and outputting various data and having an operation and control function; An input / output unit 36 for inputting and displaying various data; And a communication unit 38 for remote monitoring from the outside. The input / output unit 36 includes a separation unit 361, a display unit 362, and a storage unit 363.

According to FIG. 8, the voltage detector 31 for detecting the voltage component supplied to the load such as a motor includes a voltage detector 311 for converting the voltage component detected by the voltage detector 12 into a constant magnitude. The voltage detector 311 includes a voltage filter 312 for extracting only a frequency component of a predetermined frequency band or removing a frequency component of a predetermined frequency or more from the voltage component converted by the voltage detector 311. The current detector 33 includes a motor and the like. An image current transformer 10 for detecting a leakage current to a wire supplied to a load of the current, a current / voltage converter 331 for converting the leakage current component detected by the image current transformer 10 into a voltage component, A current filter unit 332 for removing a frequency component above a certain frequency or extracting only a frequency component of a predetermined frequency band from the leakage current component converted by the current / voltage converter 331, and the current filter It is composed of amplifying section 333 for amplifying the leakage current components detected by 332.

Hereinafter, FIG. 8 which is the first embodiment of the insulation monitoring device 30 and FIG. 10 which is an operation flowchart of the insulation monitoring device 30 will be described in detail.

As shown in FIGS. 8 and 10, various data used in the insulation monitoring device 30 as components, such as a keypad or a switch, in the main flow stored in the storage unit 363 of the insulation monitoring device 30, for example. In the case where a plurality of insulation monitoring devices 30 are installed, the input unit 361 having a function of setting data such as number address for each insulation monitoring device 30, alarm set value, and amplification rate for each component is provided. Various data settings 100 are executed. Next, various data set by the input unit 361 or various data previously stored in the storage unit 363 or various data read through the communication unit 38 at an external remote location. ) Is executed.

Next, when the Va, Ib read & store 125 is executed, the leakage current Io and the voltage detecting means 12 detected by the image current transformer 10 of the embodiment of the insulation monitoring system of Figs. The detected voltage component is input to the insulation monitoring device (30). The voltage component detected by the voltage detecting means 12 is divided into voltages usable by the insulation monitoring device 30 using a resistor, a capacitor, or a transformer in the voltage detecting unit 311 and is output as a Va3 value.

Since the Va3 voltage component is a component in which various frequencies generated in the VVVF 8 are mixed, the voltage filter unit 312 removes a frequency higher than the commercial frequency component or extracts only a frequency band within the frequency control range of the VVVF 8. The voltage component Va4 is output to the analog / digital converter 32.

The voltage component Va4 value input to the analog-digital converter 32 is converted into a digital value, read by the arithmetic and control unit 35, and stored in the storage unit 363.

As described above, the leakage current component Io detected through the image current transformer 10 is converted into a voltage component in the current / voltage converter 331 for converting the current into a voltage, and in the current filter unit 332. The leakage current component Ib amplified by the amplifier 333 to the analog / digital converter 32 by removing the frequency higher than the commercial frequency component or extracting only the frequency band within the frequency control range of the VVVF 8. Output The leakage current component Ib inputted to the analog / digital converter 32 is converted into a digital value, read by the arithmetic and control unit 35, and stored in the storage unit 363.

Next, when the calculation & display 130 of FIG. 10 is executed, the definition of the constant for the amplification factor or gain, which is calculated as follows and used in the next calculation, is as follows. The values are set in or stored in the storage unit 363 in advance.

A1: Amplification-related coefficients of the voltage detector 31

A2: Amplification-related coefficients of the voltage filter unit 32

B1: Amplification-related coefficients related to the primary / secondary winding ratio of the image transformer 10

B2: amplification-related coefficient of the current / voltage conversion unit 331

B3: amplification-related coefficients of the amplifier 333

B4: Amplification-related coefficients of the current filter unit 332

Io: Leakage current flowing to the ground under the operating conditions of VVVF (8)

Vf: Ground-to-earth voltage under operating conditions of VVVF (8)

V60: Phase voltage at commercial frequency (50Hz or 60Hz)

I60: Leakage current value in which the leakage current (Io) is converted into the phase voltage of the commercial frequency (50 Hz or 60 Hz).

The conversion-related amplification coefficient of the analog / digital converter 32 is set to one.

Under the operating conditions of the current VVVF 8, the leakage current Io flowing between the line 11 and the ground and the phase voltage Vf between the line 11 and the ground can be calculated as shown in Equation 1 below.

60 Hz supplied from the transformer 1 using the leakage current Io flowing between the line 11 and the ground and the phase voltage between the line 11 and the ground under the operating conditions of the current VVVF 8 of Equation 1 above. The leakage current (I60) converted into phase voltage of can be calculated by the following Equation 2.

Using the leakage current and the phase voltage calculated in Equation 1 and Equation 2, the value of the insulation resistance 9 existing between the cable line 11 and the ground can be calculated as in Equation 3 below.

또는

or

As shown in Equation 1 to Equation 3 described above, even when the operating conditions of the VVVF 8 change, the leakage current value for the voltage supplied from the transformer 1 can be accurately detected, and the leakage current data can be measured with FND or LCD. The leakage current value or state can be displayed on the display portion 362 shown on the same kind of display means or output to a display means such as an LED or a buzzer.

In addition, as described above, the value of the insulation resistance 9 due to the voltage between the actual cable line 11 or the cable line 3 and the ground can be automatically calculated and displayed on the display unit 362.

In addition, by using an input unit 361 having a function of inputting or selecting various data by means of a kind of switch or keypad, the various leakage current components and insulation resistance values are selectively displayed on the display unit 362, or The display unit 362 is larger than the alarm level (leakage current) or smaller than the alarm level input by the input unit 361 or the alarm level stored in the storage unit 363 (insulation resistance). The alarm state may be displayed on the display unit, or the various data or alarm alarms calculated above may be output through the communication unit 38.

Next, FIG. 4, FIG. 9 (FIG. 10), and FIG. 12, which are a second embodiment of the insulation monitoring apparatus 30, will be described.

4 is an embodiment in which the line voltage is detected using the voltage detecting means 12, 13 for detecting the voltage component of the wire line 11, and other items are the same as in FIG.

FIG. 9 is a block diagram of FIG. 10. The principle is the same as that of FIG. 7, except that the positions of the amplifier 333 and the current filter 332 are changed, and the zero cro part 34 is added.

Another embodiment of the present invention according to Figure 9 includes a voltage detector 31 for detecting a voltage component supplied to a load, such as a motor, and converts it to a constant magnitude; A counter for detecting the frequency of the component detected by the zero cross section 34 and the zero cross section 34 having a function of comparing and detecting the zero points of the voltage components extracted by the voltage detector 31. Section 342;

An image transformer 10 for detecting a leakage current to a wire supplied to a load such as a motor, and a current / voltage converter 331 for converting the leakage current component detected by the image transformer 10 into a voltage component. And an amplifying unit 333 for amplifying the leakage current component converted by the current / voltage converting unit 331 and a frequency component having a predetermined frequency or higher from the leakage current component amplified by the amplifying unit 333 or A current detector 33 comprising a current filter 332 for extracting only frequency components of the frequency band;

Converting an analog component of the output value Va2 of the voltage detector 31, the output value Ia of the amplifier 333, and the output value Ib of the current filter unit 332 to a digital component Analog / digital converter (32); An operation control unit 35 for reading and outputting various data and having an operation and control function; An input / output unit 36 having a function of inputting and displaying various data or alarm display; And a storage unit 363 having a function of storing various data. The image current transformer 10, the current / voltage converter 331, the amplifier 333, and the current filter 332 The detected leakage current component is compared with the voltage component detected by the voltage detecting means and the voltage filter unit, and converted into a leakage current component (I60) or an insulation resistance (R) with respect to a voltage of a commercial frequency component of 50 Hz or 60 Hz. Characterized in that.

12 and 10, a process of converting the leakage current component I60 or the insulation resistance R with respect to the voltage of the commercial frequency component will be described.

In the main flow stored in the storage unit 363 of the insulation monitoring device 30, a component such as a keypad or a switch is provided with various data used in the insulation monitoring device 30, for example, a plurality of insulation monitoring devices 30. 11, various data settings 100 of FIG. 11 are executed in an input unit 361 having a function of setting data such as the number address for each insulation monitoring device 30, an alarm set value, an amplification factor for each component, and the like. .

Next, various types of data set by the input unit 361 or various types of data previously stored in the storage unit 363 or various types of data read through the communication unit 38 from an external remote location are read. The operation of is executed.

Next, when Va, fa, Ia, Ib read & store 120 is executed, the leakage current Io detected by the image current transformer 10 and the voltage components detected by the voltage detection means 12, 13 are insulation monitoring devices. It is input to 30. The voltage component detected by the voltage detecting means 12 and 13 is divided into voltages usable by the insulation monitoring device 30 using a resistor, a capacitor or a transformer in the voltage detecting part 311 and output as a Va1 value.

Since the Va1 voltage component is a component in which various frequencies generated in the VVVF 8 are mixed, the voltage filter unit 312 removes a frequency higher than a commercial frequency component or extracts only a frequency band within the frequency control range of the VVVF 8. The voltage component Va2 is output to the zero cross unit 34 and the analog / digital converting unit 32.

The voltage component Va2 input to the analog / digital converter 32 is converted into a digital value, read by the arithmetic and control unit 35, and stored in the storage unit 363. In addition, the AC component of the voltage component Va2 extracted by the voltage filter unit 311 compares the zero point in the zero cross part 341. When the value is greater than zero, the digital value is high. The counter unit 342 detects the frequency by converting the signal to a frequency difference. The frequency fa detected by the counter unit 342 is output to the arithmetic and control unit 35 so that the arithmetic and control unit 35 reads the frequency fa of the cable line 11 and stores it in the storage unit 363. As described above, the leakage current component Io detected through the image current transformer 10 is converted into a voltage component in the current / voltage converter 331 for converting current into voltage and amplified by the amplifier 333. The leakage current component Ia is output to the current filter unit 332 and the analog / digital converting unit 32.

The leakage current component Ia input to the analog / digital converter 32 is converted into a digital value, read by the arithmetic and control unit 35, and stored in the storage unit 363. In addition, the leakage current component Ia amplified by the amplifying unit 333 is a leakage current obtained by removing a frequency higher than a commercial frequency component by the current filter unit 332 or extracting only a frequency band within the frequency control range of the VVVF 8. The component Ib is output to the analog / digital converter 32.

The leakage current component Ib value input to the analog / digital converter 32 is converted into a digital value, read by the arithmetic and control unit 35, and stored in the storage unit 363.

Next, when the calculation & display 130 of FIG. 12 is executed, the definition of the constant for the amplification factor or the gain calculated as follows and used in the following equation is as follows, and these values are inputted to the input unit 361. Values set or stored in the storage unit 363 in advance.

A1: Amplification-related coefficients of the voltage detector 311

A2: Amplification-related coefficients of the voltage filter unit 332

B1: Amplification-related coefficients related to the primary / secondary winding ratio of the image transformer 10

B2: Amplification-related coefficients of the current / voltage converter 311

B3: amplification-related coefficients of the amplifier 333

B4: Amplification-related coefficients of the current filter unit 332

Io: Leakage current flowing to the ground under the operating conditions of VVVF (8)

Vf: Ground-to-earth voltage under operating conditions of VVVF (8)

V60: Phase voltage at commercial frequency (50Hz or 60Hz)

I60: Leakage current value in which the leakage current (Io) is converted into the phase voltage of the commercial frequency (50 Hz or 60 Hz).

The amplification coefficient related to the conversion of the analog / digital converter 32 is set to one.

Under the operating conditions of the current VVVF (8), the leakage current (Io) flowing between the line 11 and the ground and the phase voltage (Vf) between the line 11 and the ground can be calculated as shown in Equation 4.

In the operating conditions of the current VVVF (8) above, the transformer 1 is supplied from the transformer 1 using the leakage current Io flowing between the line 11 and the ground and the phase voltage between the line 11 and the ground. The leakage current (I60) converted to a phase voltage of 60 Hz can be calculated by the following Equation 5.

Using the leakage current and the phase voltage calculated in Equation 4 and Equation 5, the value of the insulation resistance 9 existing between the line 11 and the ground can be calculated as in Equation 6 below.

또는

or

As shown in Equation 4 to Equation 6 described above, even if the operating conditions of the VVVF 8 change, the leakage current value for the voltage supplied from the transformer 1 can be accurately detected, and the leakage current data can be converted into FND or LCD. The leakage current value or state can be displayed on the display portion 362 shown on the same kind of display means or output to a display means such as an LED or a buzzer. In addition, as described above, the insulation resistance R value due to the voltage between the actual cable line 11 or the cable line 3 and the ground may be automatically calculated and displayed on the display unit 53.

In addition, by using an input unit 361 having a function of inputting or selecting various data by means of a kind of switch or keypad, the various leakage current components and insulation resistance values are selectively displayed on the display unit 362, or The display unit 362 is larger than the alarm level (leakage current) or smaller than the alarm level input by the input unit 361 or the alarm level stored in the storage unit 363 (insulation resistance). The alarm state can be displayed on the display unit, and the operating frequency of the current VVVF 8 can also be displayed on the display unit 362 using the fa value stored in the storage unit 363, or via the communication unit 38. Can output various data or alarm alarm calculated in

The configuration of the insulation monitoring device 30 of FIG. 10, which is the second embodiment of the present invention described above, detects the leakage current component through the image current transformer 10 and converts the leakage current component into a voltage at the current / voltage converter 331. Component, amplified by the voltage component through the amplifier 333, and the amplified value is filtered in the current filter unit 332. In FIG. 8, the leakage current component is detected through the image current transformer 10, the value is converted into a voltage component by the current / voltage converter 331, and then filtered by the current filter unit 332. There is a difference configured in the order of amplification at 333.

In the exemplary embodiment of the present invention, the voltage detecting unit 331 is formed in the insulation monitoring device 30 inside the wire path 11 to detect the voltage component, but the portion having the function of the voltage detecting unit 331 is an insulation monitoring device ( There may be an embodiment configured outside of 30). In order to detect the leakage current, the current / voltage converter 331 has an internal configuration of the insulation monitoring device 30. However, if an electronic component such as a resistor is directly connected to the secondary side of the image current transformer 10, the insulation monitoring is performed. There may be an embodiment in which a portion having a function of the current / voltage converter 331 of the device 30 is configured outside the insulation monitoring device 331. An embodiment of the amplifying unit 333 having a function of the current / voltage converting unit 331 may be engaged in various tasks related to the present invention without departing from the gist of the present invention. It is obvious that a technician can easily apply the application.

According to the present invention, in a power facility that controls a load such as a motor, the insulation state of the line including the load can be accurately detected the leakage current or the insulation resistance value with respect to the voltage supplied from the transformer regardless of the operating conditions of the VVVF. .

In addition, a communication unit having a function of displaying an alarm state on the display unit or by communicating with or controlling a remote control unit located at a remote location by comparing the alarm level input from the input unit with the alarm level stored in the storage unit. It can remotely monitor various data or alarm status detected remotely.

Claims (6)

In the insulation monitoring system for monitoring the insulation state of the load circuit, such as a motor, A voltage detector for detecting a voltage component supplied to a load such as a motor and converting the same into a predetermined magnitude; An image current transformer for detecting a leakage current to a wire supplied to a load such as a motor, and a current detection unit for converting the leakage current component detected by the image current transformer into a voltage component to extract only a frequency component; An analog / digital converter for converting an analog component of the output value of the voltage detector and the output value of the current detector to a digital component; An operation control unit for reading and outputting various data and having an operation and control function; An insulation monitoring system comprising an input / output unit for inputting and displaying various data. 2. The current transformer according to claim 1, wherein the current detector comprises: an image current transformer for detecting a leakage current in a wire supplied to a load such as a motor; and a current / voltage converter for converting a leakage current component detected by the image current transformer into a voltage component. And a current filter unit for removing a frequency component above a predetermined frequency or extracting only a frequency component of a predetermined frequency band from the leakage current component converted by the current / voltage converter, and amplifying the leakage current component detected by the current filter unit. Insulation monitoring system, characterized in that consisting of amplification unit. In the device for monitoring the insulation state of the load circuit, such as a motor driven by VVVF having a function of controlling voltage and frequency, A voltage detector for detecting a voltage component supplied to a load such as a motor and converting the same into a predetermined magnitude; A zero cross section having a function of comparing and detecting zero points of the voltage components extracted by the voltage detecting section, a counter section for detecting a frequency of the component detected by the zero cross section; An image current transformer for detecting a leakage current to a wire supplied to a load such as a motor, a current / voltage conversion unit for converting the leakage current component detected by the image current transformer into a voltage component, and the current / voltage conversion unit A current detector comprising an amplifier for amplifying the converted leakage current component, and a current filter for removing a frequency component above a predetermined frequency or extracting only a frequency component of a predetermined frequency band from the leakage current component amplified by the amplifier; An analog / digital converter for converting an analog component of the output value of the voltage detector and the output value of the amplifier to a digital component; An operation control unit for reading and outputting various data and having an operation and control function; And an input / output unit having a function of inputting, displaying or alarming various data, and detecting the leakage current component detected by the image current transformer, the current / voltage converter, the amplifier, and the current filter unit. An insulation monitoring system, characterized in that it is converted into a leakage current component or an insulation resistance against a voltage of a commercial frequency component of 50 Hz or 60 Hz by comparing with the voltage component detected by the means and the voltage filter unit. The formula for converting the leakage current component (I 60) or the insulation resistance (R) with respect to the voltage of the commercial frequency component is calculated by the following equation. Insulation monitoring system.

or

or

here,

,

or

However, A1: amplification-related coefficients of the voltage detector, A2: amplification-related coefficients of the voltage filter section B1: Amplification-Related Coefficients for Primary / Secondary Wind Ratios of Image Current Transformers B2: amplification factor of current / voltage converter, B3: amplification factor of amplifier B4: Amplification-related Factors Io: Leakage current flowing to the ground under the operating conditions of VVVF Vf: Ground-to-earth voltage under operating conditions of VVVF V60: Phase voltage at commercial frequency (50Hz or 60Hz) I60: Leakage current value in which the leakage current (Io) is converted into the phase voltage of the commercial frequency (50 Hz or 60 Hz). The apparatus of claim 1, wherein the input / output unit comprises: an input unit having a function of inputting or selecting various data; A display unit for outputting to a display unit such as an LED or a buzzer; And a storage unit having a function of storing various data. The insulation monitoring system according to any one of claims 1 to 3, further comprising a communication unit for remote monitoring from the outside.

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