KR101224036B1 - 3 phase motor control panel with monitoring - Google Patents

Abstract

PURPOSE: A three phase control consol is provided to monitor the contact state of an electronic contactor equipped in the front end of a three phase motor when the powerthereof is on. CONSTITUTION: A three phase control consol comprises the following details: A power supply(210) supplies a power supply voltage for monitoring. A detector(220) detects an inferior insulation of the three phase motor when power is cut off or a poor contact of an electromagnetic contactor when the power thereof is on. An interface unit(230) is electrically connected with the three phase motor. An output end(240) outputs the information of insulation degradation or contact degradation.

Description

3-phase motor control panel with monitoring function {3 PHASE MOTOR CONTROL PANEL WITH MONITORING}

The present invention relates to a three-phase motor control panel with a monitoring function, and more particularly to a three-phase motor control panel having a function of monitoring the insulation state of the three-phase motor and the contact failure of the magnetic contactor.

Electrical isolation is one of the most essential components for the operation of electrical equipment and plays an important role in determining the reliability of electrical equipment. According to the survey of reliability of electrical equipment published by IEEE, EPRI, Allianz, etc. in the last 20 years, the average annual failure rate of the equipment is 3%, and the annual failure rate is high when the operation rate or load is high, or when operating under adverse conditions such as paper industry and mining. Up to 12%.

The three-phase electric motor may fail to rotate normally due to physical overload, but is mainly caused by a flash over due to a poor insulation or an image due to a poor contact of a magnetic contactor. However, these problems can be prevented by a preventive check alone, but it is practically impossible to check them from time to time.

In addition, there are many facilities that should not be stopped even if there are minor problems during operation of the three-phase electric motor.

Therefore, there is a need for a device that checks and alarms the insulation state of a three-phase motor and a poor contact state of a magnetic contactor in real time.

By the way, the conventional three-phase motor protection device is usually a current type, so that when the current flowing to the load is an overcurrent, it is cut off to prevent a large accident such as a fire immediately before or after the accident, so that it is stopped during operation It is difficult to apply to equipment that is not.

In addition, the earth leakage alarm by the image current transformer is applied as a diagnostic method of the insulation state, but it is possible only in the live state in which power is applied, and there is a capacity component between grounds, or there is a lot of noise, or a minute current flowing through high resistance of 50kΩ or more Is a symptom that can occur, but it is impossible to judge other than safety check through insulation measuring instrument.

According to the present invention, it provides a three-phase motor control panel that can monitor the insulation state of the three-phase motor when the power is cut off.

In addition, according to the present invention, it provides a three-phase motor control panel that can monitor the contact state of the magnetic contactor provided at the front end of the three-phase motor when the power supply is connected.

In addition, according to the present invention, there is provided a three-phase electric motor control panel that can simultaneously monitor the insulation state of the three-phase motor when the power is cut off and the contact state of the magnetic contactor provided at the front end of the three-phase motor when the power supply is connected.

The three-phase electric motor control panel according to the present invention includes a three-phase line drawn out between a magnetic contactor and a three-phase electric motor, and a three-phase electric motor control panel having a neutral wire as an input, the power supply unit 210 supplying a monitoring power voltage; A detection unit 220 for detecting an insulation failure of the three-phase electric motor when the power is cut off or a contact failure of the magnetic contactor when the power is connected; An interface unit 230 electrically connected to the three-phase electric motor; And an output terminal 240 for outputting insulation failure information or contact failure information.

The detection unit outputs a signal of a first level if the insulation of the three-phase motor is good, and of a second level having a different level from the signal of the first level if the insulation of the three-phase motor is poor. When the signal is output and the contact of the magnetic contactor is poor, a pulse-shaped signal which alternately moves between the first level and the second level may be output, and the insulation good, the insulation bad and the contact bad may be monitored separately. .

In addition, the detection unit 220, the first resistor (R1) connected between the power supply unit 210 and the interface unit 230; A second resistor R2 connected between the first resistor R1 and the output terminal 240; And a one-way conducting element coupled forward from the neutral line to the second resistor R2 side.

In addition, the interface unit 230 includes one-way conducting elements D1 to D3 which are forward-coupled from the detector 220 to the three-phase motor.

In addition, the detector 220 may include: a first resistor (R1) connected to a first node between the power supply unit 210 and the interface unit 230; A second resistor (R2) connected between the first node and a second node; A photodiode forward coupled from the neutral to the second node; A photo transistor connected between the monitoring power supply voltage and a third node and interlocked with the photo diode; A capacitor connected in parallel with the photo transistor; And a comparison circuit unit for comparing the potentials of the second node and the third node.

In addition, the detector 220 may include: a first resistor (R1) connected to a first node between the power supply unit 210 and the interface unit 230; A second resistor (R2) connected between the first node and a second node; A third resistor (R41) connected between the first node and a third node; A diode (D4) forward coupled from the neutral to the second node side; A diode (D5) forward coupled from the neutral to the third node side; A capacitor C coupled in parallel with the diode D5; A fourth resistor (R40) connected between the monitoring power supply voltage and the third node; And a comparison circuit unit for comparing the potentials of the second node and the third node.

In addition, the comparison circuit portion is an exclusive NOR gate.

The comparison circuit unit may include an inverter for inverting the potential level of the second node; And a NAND gate comparing the output of the inverter with the potential of the third node.

In addition, the insulation failure signal output unit including an inverter for inverting and outputting the level of the insulation failure signal output from the detection unit; And a contact failure signal output unit which maintains and outputs a pulse-shaped contact failure signal output from the detection unit at a predetermined level.

In addition, the first resistor R1 is in a range of ± 20% of the insulation resistance value allowed between the grounds.

According to the present invention, it is possible to monitor the insulation state of the three-phase motor when the power is cut off, and to monitor the contact state of the magnetic contactor provided at the front end of the three-phase motor when the power is connected, The insulation state and the contact state of the magnetic contactor provided at the front of the three-phase motor can be monitored at the same time.

1 is a conceptual diagram of a three-phase electric motor control panel according to the present invention;
2 is a main circuit diagram of a monitoring apparatus according to the present invention,
3A is a circuit diagram of a first embodiment of a monitoring apparatus according to the present invention;
3B is an output waveform diagram of a first embodiment of a monitoring apparatus according to the present invention;
4 is a circuit diagram of a second embodiment of a monitoring apparatus according to the present invention;
5 is a circuit diagram of a third embodiment of a monitoring apparatus according to the present invention;
6A is a circuit diagram of a fourth embodiment of a monitoring apparatus according to the present invention; and
6B is an output waveform diagram of a fourth embodiment of a monitoring apparatus according to the present invention.

Further objects, features and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

Before describing the present invention in detail, it is to be understood that the present invention is capable of various modifications and various embodiments, and the examples described below and illustrated in the drawings are intended to limit the invention to specific embodiments It is to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In addition, the terms "... unit", "... unit", "... module", and the like described in the specification mean a unit for processing at least one function or operation, which means hardware or software or hardware and It can be implemented in a combination of software.

In the following description of the present invention with reference to the accompanying drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and redundant explanations thereof will be omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 is a conceptual diagram of a three-phase motor control panel according to the present invention.

The three-phase electric motor control panel according to the present invention includes a magnetic contactor 110 connected to the three-phase power supply 100, a three-phase electric motor 120 electrically connected to the rear end of the magnetic contactor 110, and the magnetic contactor 110. And a three-phase line drawn out between the three-phase electric motors 120, and a three-phase electric motor control panel 130 having a neutral wire (ground) as an input. Here, the three-phase motor control panel 130 includes a monitoring device 131.

2 is a main circuit diagram of a monitoring apparatus according to the present invention, a power supply unit 210 for supplying a monitoring voltage (Vdd), a detection unit for detecting a poor insulation of the three-phase motor when the power is cut off or a poor contact of the magnetic contactor when the power is connected 220, an interface unit 230 electrically connected to the three-phase electric motor, and an output terminal 240 (Sout) for outputting insulation failure or contact failure information.

The detector 220 includes a first resistor R1 connected between the power supply 210 and the interface 230, a second resistor R2 connected between the first resistor R1 and the output terminal 240, and a neutral wire. It includes a one-way conducting element (D4) coupled forward to the second resistance side from.

) 이상을 요구하므로, 제1 저항(R1)은 대지간으로 허용되는 절연저항값의 ±20% 범위인 것이 바람직하다.Here, in the case of a three-phase 380 volt commercial power supply, the line voltage to ground is 220 volts, and the insulation resistance value allowed between grounds is 0.2 megohm (

), The first resistor R1 is preferably in the range of ± 20% of the insulation resistance value allowed between the grounds.

The interface unit 230 includes one-way conducting elements D1 to D3 coupled forward from the detector 220 to the three-phase motor side.

Looking at the main operation of the monitoring device according to the present invention.

That is, when the earth resistance becomes smaller than the resistance value of the first resistor R1 due to poor insulation in the state where the commercial power supply 100 is cut off, a voltage having a level lower than 1/2 Vdd is detected at the output terminal, and insulation If this is satisfactory and the earth resistance is larger than the resistance value of the first resistor, a voltage having a level higher than 1/2 Vdd is detected at the output end. At this time, the insulation failure can be monitored by allowing the output terminal to output the "H" or "L" signal using a CMOS gate suitable for the output terminal.

3A is a circuit diagram of a first embodiment of a monitoring apparatus according to the present invention, and FIG. 3B is an output waveform diagram of a first embodiment of the monitoring apparatus according to the present invention. Since FIG. 3A has the same configuration as that of FIG. 2 except for the detector, only the detector 320 will be described.

The operation of the detector 320 in the state where the commercial power supply 100 is cut off is the same as that of FIG. 2.

1) Insulation is good

If the insulation is good in a state where the commercial power supply 100 is cut off, there is no leakage current flowing from the power supply voltage Vdd to the motor side through the first resistor R1, and the earth resistance is at least equal to the first resistor R1. Node 1 (N1) has an "H" level because it is equal to or greater than that. Since node 1 (N1) and node 2 (N2) are equipotential, node 2 (N2) has a "H" level as well. At this time, since the photodiode PD does not operate, the phototransistor PT also does not operate, so that the node 3 N3 also has an "L" level. Accordingly, the oragate 321 outputs the "H" level.

2) Insufficient insulation

If the insulation is poor in the state in which the commercial power supply 100 is cut off, a leakage current flows from the power supply voltage Vdd to the motor side through the first resistor R1, and the earth resistance is smaller than the first resistor R1, so that node 1 N1 has an "L" level, and since node 1 (N1) and node 2 (N2) are equipotential, node 2 has a "L" level as well. At this time, since the photodiode PD does not operate, the phototransistor PT also does not operate, so that the node 3 N3 also has an "L" level. Accordingly, the oragate 321 outputs the "L" level.

3) Good insulation and poor contact

If the insulation of the motor is good, but the contact of the magnetic contactor is poor, it means that at least one of the three RST phases is repeatedly interrupted with the commercial power supply 100. Here, when the at least one phase is repeatedly broken down by the section, the connection section connected to the commercial power supply 100 for 240 degrees of 360 degrees of three phases, and the blocking cut off from the commercial power supply 100 for 120 degrees of 360 degrees It is divided into sections.

First, a connection section connected to the commercial power supply 100 will be described. At this time, the potential of the node 1 (N1) has a negative potential sufficiently lower than the ground potential, so that the photodiode PD conducts and has a "L" level. When the photodiode PD conducts, the phototransistor PT conducts, and the node 3 N3 approaches the power supply voltage Vdd and transitions to the "H" level. At this time, the node 3 N3 transitions from the "L" level to the "H" level with a predetermined time constant due to the capacitor C connected in parallel with the internal resistance r of the port transistor PT. Accordingly, the oragate 321 transitions from the "L" level to the "H" level.

On the other hand, it will be described with respect to the blocking section cut off with the commercial power supply (100). At this time, the potential of the node 1 N1 is similar to the ground potential, so that the photodiode PD has a "L" level without conduction. Since the photodiode PD does not conduct, the phototransistor PT does not conduct, and the potential of the node 3 N3 transitions from the "H" level to the "L" level with a predetermined time constant. Accordingly, the oragate 321 transitions from the "H" level to the "L" level.

That is, when the insulation of the motor is good, but the contact of the magnetic contactor is poor, the oragate OR repeatedly outputs a pulse wave as an output signal Sout, as shown in FIG. 3B.

On the other hand, when the commercial power supply 100 is applied, the insulation measurement is impossible, it can be confirmed whether the contact failure.

4 is a circuit diagram of a second embodiment of a monitoring apparatus according to the present invention. 4, only the detector 420 will be described as in FIG. 3A.

1) Insulation is good

If the insulation is good in a state where the commercial power supply 100 is cut off, there is no leakage current flowing from the power supply voltage Vdd to the motor side through the first resistor R1, and the earth resistance is at least equal to the first resistor R1. Node 1 (N1) has an "H" level because it is equal to or greater than that. Since node 1 (N1) and node 2 (N2) are equipotential, node 2 (N2) has a "H" level as well. At this time, since the capacitor C between the node 3 N3 and the neutral line N is substantially open by the application of a DC voltage, the node 3 N3 has an "H" level. Accordingly, the exclusive NOR gate (XNOR) 421 outputs the "H" level.

2) Insufficient insulation

If the insulation is poor in the state in which the commercial power supply 100 is cut off, a leakage current flows from the power supply voltage Vdd to the motor side through the first resistor R1, and the earth resistance is smaller than the first resistor R1, so that node 1 N1 has an "L" level, and since node 1 (N1) and node 2 (N2) are equipotential, node 2 has a "L" level as well. At this time, since the capacitor C between the node 3 N3 and the neutral line N is substantially open by the application of a DC voltage, the node 3 N3 has an "H" level. Accordingly, the exclusive NOR gate 421 outputs an "L" level.

3) Good insulation and poor contact

If the insulation of the motor is good, but the contact of the magnetic contactor is poor, it means that at least one of the three RST phases is repeatedly interrupted with the commercial power supply 100. Here, when the at least one phase is repeatedly broken down by the section, the connection section connected to the commercial power supply 100 for 240 degrees of 360 degrees of three phases, and the blocking cut off from the commercial power supply 100 for 120 degrees of 360 degrees It is divided into sections.

First, a connection section connected to the commercial power supply 100 will be described. At this time, the potential of the node 1 (N1) has a negative potential sufficiently lower than the ground potential so that the diode 4 (D4) conducts, and the node 1 (N1) and the node 2 (N2) have the "L" level. At this time, the diode 5 (D5) also conducts, so that the node 3 (N3) has a predetermined time constant due to the capacitor C connected in parallel with the internal resistance r of the diode 5 (D5), and the "L" at the "H" level. "Transition to the level. Accordingly, the exclusive NOR gate 421 transitions from the "L" level to the "H" level.

On the other hand, it will be described with respect to the blocking section cut off with the commercial power supply (100). At this time, the potential of the node 1 (N1) is similar to the ground potential, so that the node 1 (N1) and the node 2 (N2) have the "L" level without the diode 4 (D4) conducting. At this time, since the diode 4 (D4) does not conduct, the capacitor C between the node 3 (N3) and the neutral line (N) is substantially open by the application of a DC voltage, so that the node 3 (N3) has a predetermined time constant. Transition from the "L" level to the "H" level. Accordingly, the exclusive NOR gate 421 transitions from the "H" level to the "L" level.

That is, when the insulation of the motor is good, but the contact of the magnetic contactor is poor, the exclusive NOR gate 421 repeatedly outputs a pulse wave as an output signal Sout, as shown in FIG. 3B.

FIG. 5 is a circuit diagram of a third embodiment of a monitoring apparatus according to the present invention, in which the exclusive NOR gate 421 of FIG. 4 is replaced with an inverter 521 and a NAND gate 522. The rest of the configuration is the same.

6A is a circuit diagram of a fourth embodiment of a monitoring apparatus according to the present invention, and FIG. 6B is an output waveform diagram of a fourth embodiment of the monitoring apparatus according to the present invention.

6A further includes an insulation failure signal output unit 650 and a contact failure signal output unit 640 in the circuit diagram of FIG. 4.

The insulation failure signal output unit 650 includes an inverter 651 which inverts the insulation failure signal of the "L" level output from the detector 620 to the "H" level and outputs it.

The contact failure signal output unit 640 includes a capacitor 3 (C3) and a buffer 641 for maintaining and outputting a pulse-like contact failure signal output from the detector 620 at the "H" level.

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Accordingly, the embodiments disclosed herein are for the purpose of describing rather than limiting the technical spirit of the present invention, and it is apparent that the scope of the technical idea of the present invention is not limited by these embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: three-phase commercial power supply 110: magnetic contactor
120: three-phase electric motor 130: three-phase electric motor control panel
210: monitoring power supply voltage 220: detector
230: interface unit 240: output end

Claims (10)

In the three-phase line drawn out between the magnetic contactor and the three-phase motor, and the three-phase motor control panel that takes a neutral wire as input,
A power supply unit 210 for supplying a monitoring power voltage;
A detection unit 220 for detecting an insulation failure of the three-phase electric motor when the power is cut off or a contact failure of the magnetic contactor when the power is connected;
An interface unit 230 electrically connected to the three-phase electric motor; And
Output terminal 240 for outputting insulation failure information or contact failure information
Three-phase motor control panel with a monitoring function including a. The method of claim 1, wherein the detection unit 220,
A first resistor R1 connected between the power supply unit 210 and the interface unit 230;
A second resistor R2 connected between the first resistor R1 and the output terminal 240; And
One-way conducting element coupled forward from the neutral to the second resistor (R2) side
Three-phase motor control panel with a monitoring function including a. The method of claim 1, wherein the interface unit 230,
Three-phase electric motor control panel with a monitoring function comprising a one-way conducting element (D1 ~ D3) coupled forward from the detection unit 220 to the three-phase motor side. The method of claim 1, wherein the detection unit 220,
A first resistor (R1) connected to a first node between the power supply unit 210 and the interface unit 230;
A second resistor (R2) connected between the first node and a second node;
A photodiode forward coupled from the neutral to the second node;
A photo transistor connected between the monitoring power supply voltage and a third node and interlocked with the photo diode;
A capacitor connected in parallel with the photo transistor; And
Comparison circuit unit for comparing the potential of the second node and the third node
Three-phase motor control panel with a monitoring function including a. The method of claim 1, wherein the detection unit 220,
A first resistor (R1) connected to a first node between the power supply unit 210 and the interface unit 230;
A second resistor (R2) connected between the first node and a second node;
A third resistor (R41) connected between the first node and a third node;
A diode (D4) forward coupled from the neutral to the second node side;
A diode (D5) forward coupled from the neutral to the third node side;
A capacitor C coupled in parallel with the diode D5;
A fourth resistor (R40) connected between the monitoring power supply voltage and the third node; And
Comparison circuit unit for comparing the potential of the second node and the third node
Three-phase motor control panel with a monitoring function including a. The method of claim 5,
The comparison circuit unit is a three-phase electric motor control panel with a monitoring function, characterized in that the exclusive Noah gate. The method of claim 5,
The comparison circuit unit includes an inverter for inverting the potential level of the second node; And
NAND gate for comparing the output of the inverter and the potential of the third node
Three-phase motor control panel with a monitoring function including a. The method according to claim 6,
An insulation failure signal output unit including an inverter for inverting and outputting a level of the insulation failure signal output from the detection unit; And
A contact failure signal output unit for maintaining and outputting a pulse-like contact failure signal output from the detection unit at a predetermined level;
Three-phase motor control panel with a monitoring function further comprising a. The method according to any one of claims 2 and 4 to 8,
The first resistor (R1) is a three-phase electric motor control panel with a monitoring function, characterized in that the range of ± 20% of the insulation resistance allowed between the ground. The apparatus according to claim 1,
If the insulation of the three-phase motor is good, output the signal of the first level,
If the insulation of the three-phase motor is poor, output a signal of the second level having a different level from the signal of the first level,
And a contact signal of the electromagnetic contactor is outputted, and outputs a pulse-shaped signal alternately moving between the first level and the second level.

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