JP2006020483A - Detection device of insulation degradation for inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection device of insulation degradation for an inverter device, capable of reducing error factors caused in inverter control and detecting a slight current leakage in an inverter load circuit, with accuracy during detecting insulation degradation in the inverter load circuit. <P>SOLUTION: In detecting the insulation degradation for the inverter load circuit, a zero-phase current transformer 6, a low-pass filter 7, and an amplifier 8 are constituted in series. A zero-phase current transformer accommodating part 9 integrally constituted with the zero-phase current transformer, the low-pass filter, and the amplifier is placed on a load side of an inverter control device 3. The output from the accommodating part 9 is inputted in an insulation degradation detecting unit 11, thus reducing the influence of electromagnetic induction and the influence of the current leakage of the filter and the inverter control circuit itself. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an insulation deterioration detection device capable of detecting an insulation deterioration of a load with high sensitivity even in a system in which a high-frequency component or an unbalanced stray capacitance exists in a load circuit using an inverter control power supply. About.

Conventionally, the insulation deterioration detection of the load circuit using the inverter control power supply is performed by using the output of the zero-phase current transformer provided on the primary side (power supply side) of the inverter control device as shown in FIG. And the insulation deterioration state in the load was judged from the magnitude of the zero-phase current. In addition, as another means, there is one provided with a low-pass filter for blocking high-frequency components at the output of the zero-phase current transformer, but all of them are only on the primary side (power supply side). (For example, see Patent Document 1)
Japanese Patent Laid-Open No. 5-15046

  According to this method, the zero-phase current transformer and the insulation deterioration detection unit have the advantage that the general-purpose type that responds to the commercial frequency that has been used can be used as it is, but for the following two reasons: Insulation deterioration detection of the inverter load circuit could not be performed with high sensitivity.

  As a first reason, a line filter is used on the power supply side of the inverter control device in order to prevent a harmonic current component generated in the inverter control device from flowing back to the power supply side. The capacitance between the grounds in the line filter causes a leakage current to flow to the ground, which causes a decrease in load insulation deterioration detection sensitivity.

  As a second reason, the inverter control device often operates at a frequency other than the commercial frequency, and particularly in a high frequency region, the leakage current due to the floating capacitance to the ground inside the inverter control device increases. This is because even if the slight imbalance between the phases of the floating electrostatic capacitance is very small and negligible at the normal commercial frequency, it is several tens of times when operating in the high frequency region, and sometimes several hundred times or more. It corresponds to the leakage current. These relationships are as follows.

In the conventional system shown in FIG. 5, the AC power source 1 is grounded via the ground resistor 21. The current flowing through the ground resistor is the leakage current Io of this system, and this current has been detected using the zero-phase current transformer 6 in the past. The leakage current that flows due to the capacitance between the grounds of the line filter 2 is Io1, the leakage current due to the ground floating capacitances 22-1, 22-2, and 22-3 in the inverter control device 3 and the inverter control device 3 If the total leakage current for the insulation resistance is Io2, and the leakage current due to the insulation resistance 23 in the load 10 is Io3.
Io = Io1 + Io2 + Io3
Since Io1 and Io2 are added as unnecessary leakage currents to the leakage current Io3 at the originally required load, the value of the insulation degradation detection of the load circuit is the value of these two leakage currents Io1 and Io2. It must be the detection value in the range that is not affected.

  For example, when the ground capacitance is 1 μF, a ground leakage current of about 31 mA flows in a 50 Hz, 100 V power supply. This corresponds to about 3.2 kΩ, which is a considerably bad value as an insulation state when converted to ground insulation resistance. It was impossible to detect the insulation deterioration status of the load circuit on the order of 1 MΩ from such a large ground leakage current. When detecting insulation deterioration in equipment with large leakage currents of these Io1 and Io2, the sensitivity must be greatly reduced, and the detection of insulation deterioration of the load circuit using the inverter control power supply is highly sensitive while utilizing the load circuit. In these facilities, in order to grasp the insulation deterioration status of the load circuit, it was necessary to stop the facility and disconnect the inverter control device from the load circuit to measure the insulation resistance. .

  On the other hand, if a zero-phase current transformer is installed on the load side of the inverter control device to detect only Io3, the secondary-side current of the zero-phase current transformer is Therefore, the measurement could not be performed correctly due to the influence of surrounding electromagnetic induction.

  The object of the present invention is to be able to detect the insulation deterioration of the load circuit with high sensitivity without being affected by the ground leakage current in the line filter and the imbalance of the floating capacitance to the ground inside the inverter control device. It is an object of the present invention to provide a device for preventing secondary disasters such as damage to equipment and fire due to fire and its means.

  In order to solve the above-described problems and achieve the object, the inverter insulation deterioration detection device of the present invention is configured as follows.

(1) In an insulation deterioration detection device for a load circuit such as a motor driven by an inverter output, a zero-phase current transformer, a low-pass filter, and an amplifier are configured in series and installed on the load side of the inverter control circuit. In addition, the present invention relates to an insulation deterioration detection device for an inverter, characterized in that the output of the amplifier is used as an input of an insulation deterioration detection unit.

(2) The insulation deterioration detecting device for an inverter according to the present invention is the device described in the above (1), and a zero-phase current transformer, a low-pass filter, and an amplifier are configured in series, and these are configured integrally. The present invention relates to an insulation deterioration detecting device for an inverter which is housed in a case as a zero-phase current transformer housing.

(3) An insulation deterioration detecting device for an inverter according to the present invention is the device described in the above (1) and (2), and the insulation deterioration due to an effective current component having a component in phase with a power supply voltage as a detection method in the insulation deterioration detecting unit. It is characterized by detection.

(4) In an insulation deterioration detection device for a load circuit such as a motor driven by an inverter output, a zero phase current transformer, a low-pass filter, and an amplifier are configured in series, and these are integrally configured. The present invention relates to an insulation deterioration detection method for an inverter, characterized in that a storage unit is installed on a load side of an inverter control circuit, and an output of the amplifier is used as an input of an insulation deterioration detection unit.

  By using the zero-phase current transformer housing portion of the present invention, a load using an inverter control device can be improved by reducing the influence of electromagnetic induction and amplifying only the signal in the power supply frequency region to improve the S / N ratio. In the detection of the state of insulation deterioration, high sensitivity detection of 1 mA or less can be easily realized.

  That is, according to the present invention, the insulation deterioration state of the load circuit using the inverter control device is not stopped, the contactor having a movable part is placed at the operating position, and further the cutting circuit is used for the load circuit. If it is, it is possible to detect with high sensitivity while all the load circuits are running, such as when cooling water is flowing, so it is possible to prevent secondary disasters such as equipment damage or fire due to insulation deterioration of the load circuit. It is possible to take measures to prevent it. Since it is possible to constantly grasp the state of insulation deterioration of the load circuit, a scheduled work plan can be made without suddenly stopping the load facility, so that the operational reliability of the load facility can be greatly improved.

  In addition, if a system that responds only to the effective amount of leakage current is applied to the operation determination processing unit, it is possible to further increase the sensitivity of load insulation deterioration monitoring.

BEST MODE FOR CARRYING OUT THE INVENTION

  FIG. 1 is a diagram showing an example of an insulation deterioration detection apparatus according to the present invention. This insulation deterioration detection device detects insulation deterioration of an inverter load circuit.

  The inverter control device 3 to which power is supplied from the AC power source 1 via the line filter 2 is composed of a rectifier circuit 4 and power switch means 5, and floating capacitances 22-1, 22-22 between the ground. 2 and 22-3 respectively. The output of the inverter control device 3 is supplied to a load 10 such as a motor through a zero-phase current transformer 6. The secondary side output of the zero-phase current transformer 6 is subjected to signal amplification by the amplifier 8 immediately after the harmonic component is removed by the low-pass filter 7. The zero-phase current transformer 6, the low-pass filter 7 and the amplifier 8 are configured as a series with the wiring distance as short as possible, and are housed as a zero-phase current transformer housing portion 9 configured integrally.

  The output of the amplifier 8 is connected to an insulation deterioration detection unit 11 installed at a position where maintenance is easy, such as a control panel or a panel surface of a cubicle. The insulation deterioration detection unit 11 includes a band pass filter 12, a level detection unit 13, an operation determination processing unit 14, and an output processing unit 15, and outputs when a leakage current due to a decrease in insulation resistance in the load 10 is larger than a set predetermined value. 16 is issued.

  By setting the installation position of the zero-phase current transformer 6 to the load side of the inverter control device 3, the leakage current Io1 flowing through the filter 2 and the leakage current Io2 flowing through the internal stray capacitance of the inverter control device 3 are reduced. Since only the leakage current Io3 flowing through the load 10 that is not included can be detected, insulation monitoring at the load 10 can be performed with high sensitivity.

  Furthermore, since the environment in which the zero-phase current transformer housing 9 is installed is often near the load of a motor or the like, it is electromagnetically dirty and easily affected by electromagnetic induction. In particular, the output of the zero-phase current transformer 6 is usually in a very low voltage region of 1 V or less, and correct determination becomes impossible when affected by electromagnetic induction. Therefore, the zero-phase current transformer 6, the low-pass filter 7 and the amplifier 8 are arranged very close to each other, so that the signal portion having a low voltage level is not routed so that it is less affected by electromagnetic induction and is unique to the inverter control circuit. The S / N ratio can be greatly improved by amplifying after removing the carrier frequency component and the harmonic component of the above by a low-pass filter.

  The selection of the case for housing the zero-phase current transformer 6 built in the zero-phase current transformer housing unit 9 and the low-pass filter 7 and the amplifier 8 is not particularly limited in terms of material and shape, but is a shield type. More preferred. By performing the shielding process, the influence of electromagnetic induction can be further reduced.

  Further, as a determination method performed by the operation determination processing unit 14 in the insulation deterioration detection unit 11, a method (Io detection method) in which only the magnitude of the leakage current is determined may be used, or the effective current determination voltage input 17 may be used. It is also possible to use a method of connecting and detecting only an effective leakage current in the same phase direction as the voltage phase (Ior detection method). In any method, the leakage current that flows due to the insulation deterioration of the load 10 is supplied from the ground resistor 21 in the AC power supply 1 and thus matches the power supply frequency. Therefore, the insulation deterioration detection unit 11 corresponding to the power supply frequency is used. Can be applied.

  In addition, this invention is not limited only to the said embodiment, In the range which does not change a summary, it can deform | transform suitably and can be implemented.

It is a block diagram of the insulation degradation detection apparatus concerning the 1st Embodiment of this invention. It is a block diagram of the insulation degradation detection apparatus concerning the 2nd Embodiment of this invention. It is a block diagram of the insulation degradation detection apparatus concerning the 3rd Embodiment of this invention. It is a block diagram of the insulation degradation detection apparatus concerning the 4th Embodiment of this invention. It is a block diagram which shows one example of the conventional insulation deterioration detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... AC power source, 2 ... Filter, 3 ... Inverter control device, 4 ... Rectifier circuit, 5 ... Power switch means, 6 ... Zero phase current transformer, 7 ... Low-pass filter, 8 ... Amplifier, 9 ... Zero phase change Current-carrying unit, 9 '... shielded zero-phase current transformer containing unit, 10 ... load, 11 ... insulation deterioration detection unit, 12 ... band-pass filter, 13 ... level detection unit, 14 ... operation determination processing unit, 15 ... Output processing unit, 16 ... output of insulation deterioration detection unit, 17 ... voltage input for determining effective current, 21 ... ground resistance, 22-1, 22-2, 22-3 ... floating capacitance, 23 ... insulation resistance, 24. Shield processing part,

Claims (4)

  In an insulation deterioration detection device for a load circuit such as a motor driven by an inverter output, a zero-phase current transformer, a low-pass filter, and an amplifier are configured in series, and these are installed on the load side of the inverter control circuit. An insulation deterioration detection device for an inverter device, wherein an output of an amplifier is used as an input of an insulation deterioration detection unit.   2. The insulation deterioration detection for an inverter device according to claim 1, wherein a zero-phase current transformer, a low-pass filter, and an amplifier are configured in series, and the zero-phase current transformer housing portion is configured integrally. apparatus.   The insulation deterioration detection device for an inverter device according to claim 1, wherein the insulation deterioration detection unit detects an insulation deterioration by an effective current that is a component in phase with the power supply voltage as a detection method of the insulation deterioration detection unit.   In an insulation deterioration detection device for a load circuit such as a motor driven by an inverter output, a zero-phase current transformer, a low-pass filter, and an amplifier are configured in series, and these are installed on the load side of the inverter control circuit. An insulation deterioration detection method for an inverter device, wherein an output of an amplifier is used as an input of an insulation deterioration detection unit.

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