KR20040033462A - Earth level detecting appratus of motor - Google Patents

Abstract

PURPOSE: An apparatus for detecting a ground level of a motor is provided to monitor an isolating state of the motor by detecting amount of ground current at on/off line in real time. CONSTITUTION: An apparatus for detecting a ground level of a motor includes a power supply(10), a level detector(20), an AD/DC converter(30), a filter and amplifier(40), a relay output unit(50), an isolating amplifier(60), and a V/I conversion output unit(70). The power supply(10) is used for converting AC power to DC power to apply the DC power to each element or convert the DC power to supply necessary voltage. The level detector(20) is used for detecting a ground level of output current of an inverter. The AD/DC converter(30) is used for converting AC elements of detection signals of the level detector to DC elements. The filter and amplifier unit(40) filters and amplifies voltage signals of the AD/DC converter. The relay output unit(50) compares the voltage signals to a reference value and outputs a contact signal according to a compared result. The isolating amplifier(60) is used for isolating the overcurrent and the noise of the voltage signals. The V/I conversion output unit(70) converts the voltage signals to current signals.

Description

Ground level detection device of the motor {EARTH LEVEL DETECTING APPRATUS OF MOTOR}

The present invention detects in real time the grounding amount generated by the ground fault in the main circuit line of the motor installed in the site with poor ambient conditions, and always monitors whether the insulation of the motor is poor, as well as when the ground level reaches a certain amount The present invention relates to a motor ground level detection device for preventing damage to the motor, control panel failure, and human electric shock by allowing maintenance and repair work to be performed in advance.

Generally, motors used in various fields are classified into winding type motors and squirrel type motors, and drives for driving the motors can be classified into direct control type using a magnetic contactor, secondary resistance control type, and inverter control type. have.

The ground voltage detection device used locally in the main circuits of the drive and the motor is used as a maintenance table for field motors because the detection level of the ground voltage is high and the detection target is limited to the occurrence of ground instead of a quantitative signal. There was a limit.

In particular, some circuits such as inverters have a non-sinusoidal characteristic of P.W.M (Pulse Width Modulation) method, which is not a sinusoidal wave, so that ground level detection is difficult.

Therefore, in the related art, since the ground levels of the motor and the drive circuit have not been accurately detected, there is a problem that the motor burnout occurs, and the burnout of the power power device due to the poor synchronization occurs due to the unbalance of the input voltage.

The present invention has been made in view of the above-mentioned problems, and the ground amount of the main circuit is always detected as a quantitative analog amount on and off and at the same time, if a certain reference level is exceeded, a fault signal is generated and the motor is burned out. And to provide a ground level detection device for the motor to prevent the control panel panel failure and human electric shock in advance.

Another object of the present invention is to provide a ground level detection device for a motor that can detect the grounding amount accurately and quantitatively even in an inverter circuit having a non-sinusoidal output characteristic, and does not affect the inverter or the main circuit and has a simple installation To provide.

1 is a block diagram showing a schematic configuration of a ground level detecting apparatus according to the present invention.

Figure 2 is a circuit diagram showing an embodiment of the ground level detection apparatus according to the present invention.

3 is an embodiment of a ground level detection apparatus according to the present invention.

Description of the main symbols in the drawings

10: power supply unit 20: detection unit

30: AC / DC converter 40: filter and amplifier

50: comparison and output unit 60: isolation and differential amplifier

70: V / I converter and analog output

As a construction means for achieving the above object of the present invention, the present invention is a ground level detection device of a motor device comprising an inverter,

A power supply unit for reducing the commercial AC power to rectify the DC voltage at a predetermined level, applying the power to an operation circuit to each circuit, and converting the DC voltage to supply a required voltage;

A level detecting unit detecting a ground level through the deviation of the phase current output from the inverter;

An AC / DC converter for converting an AC component of the detection signal detected by the level detector into a DC component;

A filter and amplifying unit for filtering and amplifying a voltage signal indicating a ground level output from the AC / DC converter;

A relay output unit which notifies a failure by comparing a voltage signal indicating a ground degree input through the filter and amplifier with a preset reference value and outputting a contact signal by driving a relay than the reference value;

An insulation amplifier to insulate the overcurrent and noise of the voltage signal indicating the grounding degree inputted through the filter and the amplifier;

And a V / I conversion output unit which receives a voltage signal indicating the grounding degree from the insulation amplifier and converts the signal into a current signal in a predetermined range.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a functional configuration of a ground level detecting apparatus of a motor according to the present invention, wherein the apparatus is to reduce the commercial AC power to rectify the DC voltage at a predetermined level, and apply it as an operating power source to each circuit. In addition, the power supply unit 10 for converting the DC voltage to supply the required voltage, the level detector 20 for detecting the ground level through the deviation of the phase current output from the inverter, and the detection signal detected by the level detector 20 AC / DC converter 30 for converting an AC component into a DC component, and a filter and amplifier 40 for filtering and amplifying a voltage signal indicating the grounding degree output from the AC / DC converter 30. And relaying a voltage signal indicating a ground degree input through the filter and amplifying unit 40 to a preset reference value to drive a relay rather than the reference value to output a contact signal to signal a failure. The grounding degree from the output part 50, the insulation amplifier 60 to insulate the overcurrent and noise of the voltage signal indicating the grounding degree input through the filter and amplifier 40, and the grounding degree from the insulation amplifier 60 And a V / I conversion output unit 70 which receives a voltage signal, which is converted into a current signal in a predetermined range, and outputs the converted signal.

In the above description, the relay output unit 50 includes a setting unit 51 for setting the uppermost value of the motor ground level, a detection voltage applied from the filter and amplifying unit 40 and a reference level of the setting unit 51. In comparison, the comparison unit 52 determines whether the detected value is equal to or greater than the reference level, and the relay unit 53 which operates when the detected value is greater than or equal to the reference level to output a contact signal indicating a failure. It is composed of

FIG. 2 shows an example of an actual circuit configuration for each means shown in FIG. 1. Referring to this, the operation of each means will be described below.

First, the power supply unit 10 converts a commercial AC power supply 110V / 220V into an AC signal of 15V through the down transformer (T1). Then, the reduced 15V AC voltage is rectified and filtered in the direction of the arrow by the characteristics of the bridge diode BD6 and the capacitors C17, C12, and C20, and rectified to a DC voltage of 38V. ), And a DC voltage of ± 12 V is generated at the output terminals of the constant voltage ICs U6 and U8 and supplied to each circuit as driving power. At this time, if the constant voltage is normal, the lamp D7 is turned on.

In addition, the constant voltage DC ± 12V is input to the DC / DC converter 12 to generate an isolated constant voltage ISO ± 12V, two power supplies are generated.

Then, the level detector 20 receives the R, S, T phase and ground signals output from the inverter, and when a deviation of the current flowing in each phase flows through the resistor R51, a predetermined divided voltage is applied to the level R, The voltage INV-EL-Vout output from the level detector 20 is expressed by Equation 1 below.

The voltage level between the ground and INV-EL-Vout output from the level detector 20 is input to the AC / DC converter 30 and converted into a DC signal.

The AC / DC converter 30 is a circuit for converting a voltage detected as an AC component from the output terminal INV-EL-Vout of the level detector 20 into a DC component so that a comparison process can be performed at a later stage.

That is, when the voltage of the output terminal INV-EL-Vout is positive, the current flows from the resistor R6 to the diode D1 to the OP AMP U1 (6 pins) to amplify 20: 1. , The value is converted into a constant voltage by a 1: 1 inverting amplification of the OP AMP (U2).

If the voltage at the output terminal (INV-EL-Vout) is positive, current flows from the OP AMP (U1) to the diode (D1)-> resistor (R20)-> resistor (R6) for 20: 1 amplification. The value is converted into a constant voltage signal by 1: 1 non-inverting amplification of OP AMP (U2).

When the amplification process is expressed by Equation 2, Equation 2 below.

The output of the AC / DC converter 30 is input to the filter and amplifier 40 to remove the noise signal.

The filter and amplifier 40 inverts and amplifies the output V2out of the AC / DC converter 30 by the OP AMP U3A, filters the capacitor C1, and filters the variable resistor VR3. Zero adjustment is performed to apply the result to the relay output section 50 and the insulation amplifier section 60.

The output voltage V3out output from the filter and amplifier 40 is expressed by Equation 3 below.

The relay output unit 50 compares the V3out value obtained by converting the level of ground level applied from the filter and amplifier 40 to a DC level, and the set value set by the setter 51, and compares the V3out value to the set value. If large, current flows in the direction of the arrow, the relay is turned on, the lamp D2 is turned on, and the contact output is sent out. The contact output of the relay is used as a fault signal.

The output of the comparison OP AMP (U3B) is as shown in Equation 4 below.

In the above, TP3 is a setting value of the setter 51. Therefore, when the set value is larger than the measured value V3out, the output of the OP AMP U3B is -12V, and when the measured value V3out is larger than the set value, the output of the OP AMP U3B is + 12V.

In addition, the isolation amplifier unit 60 is a noise isolation unit included in the detection signal V3out and includes an isolation amplifier configured as a differential input / differential output. When the output voltage V3out of the filter and amplifier 40 is divided by a plurality of resistors (Vin + = VR6 (middle tap) / (R24 + VR6) * V3out) and applied to the insulation amplifier U4, It is converted into analog → digital → optical → digital → analog signal and differentially amplified inside the isolation amplifier U4. When overcurrent (for example, 200mv or more) is not applied, the input terminal (Vin +) and the output terminal (Vout +) are applied. The same value appears in.

The signal representing the level of ground level amplified by the isolation amplifier unit 60 is again input to the V / I conversion output unit 70. The V / I conversion output unit 70 converts the ground level into a current signal. To output a signal in the range of 4-20mA.

That is, the voltages Vout + and Vout − output from the isolation amplifier unit 60 are input to the OP AMP U5A, differentially amplified by 100 times, and then applied to the inverting input terminal of the OP AMP U5B. The output of the OP AMP U5B rises to the positive polarity and is applied as a drive current to the base of the transistor Q2 through the resistors and the diode D5 to be output to the output OUT1, and a load is applied between the output terminals OUT1 and OUT2. The feedback voltage is applied across the resistor R5 by the load current. The process is represented by the following equation (5).

Therefore, a contact signal indicating a failure is output from the relay output unit 50 when the ground level is equal to or greater than the reference value (set value TP3), and the V / I conversion output unit 70 detects the level detection unit 10. A current signal quantitatively indicating the ground level value is output.

Figure 3 shows an embodiment of the appearance of the ground level detection apparatus according to the present invention, the input terminals (R-IN, S-IN, T-IN) connected to the U, V, W phase output terminal of the inverter and Output terminals OUT1 and OUT2 for expressing the ground level as a current signal within a predetermined range, and output terminals A, B, and C for outputting a relay contact signal indicating whether a failure occurs, and a power terminal for inputting a power supply voltage ( L0, L1, L2, a ground terminal G connected to ground, and a predetermined operation button.

3 is to help the understanding of the present invention, and does not limit the technical scope of the ground level detection apparatus.

As described above, the ground level detector according to the present invention can be applied irrespective of the winding type motor and the squirrel motor, and the ground level detector can be accurately detected in the inverter circuit, which is a non-sinusoidal circuit. Through the operation of the present invention, it is possible not only to quantitatively detect the quantitative amount from several kilohms to several megaohms in advance, but also to set the error level according to the environment and conditions through arbitrary setting. Of course, it prevents the power devices such as thyristors and IGBTs from being burned out by the ground fault and other control panels caused by the pulse failure caused by the ground fault. It can be monitored all the time, preventing facility shutdown due to accidental operation failure and depending on the grounding situation. Through the planned tissue it has the advantage of pre-maintenance and replacement motor as possible.

Claims (2)

In the ground level detection device of a motor device including an inverter, A power supply unit for reducing the commercial AC power to rectify the DC voltage at a predetermined level, applying the power to an operation circuit to each circuit, and converting the DC voltage to supply a required voltage; A level detecting unit detecting a ground level through the deviation of the phase current output from the inverter; An AC / DC converter for converting an AC component of the detection signal detected by the level detector into a DC component; A filter and amplifying unit for filtering and amplifying a voltage signal indicating a ground level output from the AC / DC converter; A relay output unit which notifies a failure by comparing a voltage signal indicating a ground degree input through the filter and amplifier with a preset reference value and outputting a contact signal by driving a relay than the reference value; An insulation amplifier to insulate the noise and the overcurrent of the voltage signal indicating the grounding degree inputted through the filter and the amplifier; And a V / I conversion output unit which receives a voltage signal indicating the grounding degree from the insulation amplifier and converts the voltage signal into a current signal in a predetermined range. The method of claim 1, wherein the relay output unit A setting unit for setting the upper limit of the motor ground level, A comparison unit for comparing the detection voltage applied from the filter and the amplifier with a reference level of the setting unit to determine whether the detected value is equal to or greater than the reference level; And a relay unit configured to output a contact signal indicating a failure by operating when the detection result of the comparison unit is greater than or equal to a reference level.