KR102232026B1 - Motor control system having digital-zero relay controller - Google Patents

Abstract

A motor control panel system including a digital-zero relay controller (D-ZRC) includes: a wiring breaker in which a CT for measuring a current is mounted, and configured to receive a power by an input side through a distribution line, transmit the power to a load on an output side, and block supply of the current according to a state of the current supplied to the load; a zero relay (ZR) in which the relay is turned on and off under control of the digital-zero relay controller according to a state of the current or a voltage supplied from the wiring breaker to a final load, and a relay ON state is maintained by a magnetic force of a permanent magnet so that a standby power generated by a magnetic force of an AC electromagnet becomes zero; a digital-zero relay controller (ZRC) for collecting and analyzing current information from the CT mounted in the wiring breaker and voltage information from an input terminal of the zero relay, respectively, and selectively tripping the wiring breaker or the zero relay based on analysis information to cut off supply of the current; and an electric motor that is the final load operated by driving of the wiring breaker or the zero relay. Accordingly, a system is controlled in a dualized way to trip an instantaneous large current and arc transient current, which were impossible to be tripped by an existing EOCR, so that the system is protected more efficiently.

Description

Motor control panel system equipped with digital zero relay controller {MOTOR CONTROL SYSTEM HAVING DIGITAL-ZERO RELAY CONTROLLER}

The present invention relates to a motor control panel system equipped with a digital zero relay controller, and more particularly, a digital device that dually detects an overcurrent caused by a general overload supplied to the motor and an instantaneous large current caused by abnormal phenomena such as failure. A zero relay controller (D-ZRC: Digital-Zero Relay Controller) selectively cuts off the zero relay (ZR) connected to the front end of the motor or the MCCB (Molded Case Circuit Breaker) that receives power from an external power facility. It relates to a motor control panel system equipped with a digital zero relay controller to prevent burnout of the zero relay.

EOCR (Electronic Overload Relays) detects the flow of more than the allowable current or voltage to prevent burnout of the motor in the industrial field and controls the magnetic contactor (MC) to cut off the power. have.

Existing EOCR (Electronic Overload Relays) is specialized to control only the existing MC (magnetic contactor), which is a contact type that does not have arc extinguishing and blocking capabilities. In the case of opening/closing with an MC (electronic contactor) (including abnormal current such as short-circuit current, arc current, etc. more than ~8 times), there is a problem that a small breakdown occurs or tripping is impossible due to the burnout of the magnetic contact of the internal MC.

In addition, the conventional magnetic contactor (MC: Magnetic Contactor) maintains the ON state so that the three-phase input power is transferred to the output-side load while the power is applied under the principle of an electromagnet. There is a problem with this consumption.

Korean Patent Application Publication No. 10-2016-0019733 (2016.02.22)

In order to solve the above-described problem, the present invention detects the current from the CT built in the wiring breaker, trips the arc extinguishing for general overcurrent and a zero relay (ZR) without blocking capability, and the arc for instantaneous high current. An object of the present invention is to provide a motor control panel system equipped with a digital zero relay controller that selectively trips a molded case circuit breaker (MCCB) with extinguishing and breaking capability to prevent damage to the zero relay. In addition, the zero relay controller has the purpose of preventing accidents in advance by controlling the smart viewer according to the cause of the trip and transmitting it to the user when the wiring breaker or the zero relay is selectively tripped.

In addition, the zero relay controller collects and analyzes current information from a CT built in a wiring breaker, so that it does not have an independent CT like a conventional EOCR.

In order to solve the above-described problem, the present invention connects an input coil, a trip coil, and a zero relay (ZR) equipped with a permanent magnet to the front end of the motor, and applies power to the input coil on the fixed terminal side. After the movable terminal and the fixed terminal are in contact with the permanent magnet and attractive force, the movable terminal and the fixed terminal remain in contact with the magnetic force of the permanent magnet even if the power supplied to the input coil is cut off. The city aims to provide a motor control panel system equipped with a digital zero relay controller that does not consume standby power. In addition, conventionally, an ON contact point is maintained by an alternating current electromagnet, which has the purpose of solving a problem of low power quality such as an instantaneous power failure due to a shaking phenomenon caused by an alternating current contact point.

The motor control panel system equipped with a digital zero relay controller according to the present invention for achieving the above object has a built-in CT that measures current, receives power from the input side through the distribution line, and supplies the power to the load while delivering the power to the load on the output side. A wiring breaker that cuts off the supply of current according to the state of the current; Depending on the state of the current or voltage supplied from the distribution breaker to the final load, the relay is turned on (ON) and off (OFF) by the control of the digital zero relay controller (D-ZRC), and the relay on (ON) state is a permanent magnet. A zero relay (ZR) in which standby power generated by the magnetic force of the alternating current electromagnet becomes zero by being maintained by the magnetic force of Digital zero relay that collects and analyzes current information from the CT built in the wiring breaker and voltage information from the input terminal of the zero relay, and selectively trips the wiring breaker or zero relay based on the analysis information to cut off the current supply Controller (ZRC); And an electric motor that is a final load operated by driving the wiring breaker or the zero relay.

Preferably, the D-ZRC of the motor control panel system equipped with a digital zero relay controller according to the present invention for achieving the above object is visually distinguished from each other according to the corresponding trip cause when the wiring breaker or the zero relay is selectively tripped. It characterized in that the control further includes a smart viewer.

More preferably, the D-ZRC of the motor control panel system equipped with a digital zero relay controller according to the present invention for achieving the above object is a first CT formed on any two of the single-phase or three-phase wired to the wiring breaker. By analyzing the current information collected from the and the second CT, when an overcurrent lower than the instantaneous large current is detected, the zero relay is selectively tripped, and when a current exceeding the instantaneous large current is detected, the wiring breaker is selectively tripped. Prevent zero relay burnout,

When the current value input to the motor exceeds the instantaneous high current value preset in the current & voltage setting unit 330, the trip signal of the zero relay is stopped and the trip signal is transmitted only to the wiring breaker.

In the motor control panel system equipped with a digital zero relay controller according to the present invention, a digital zero relay controller (D-ZRC) can cut off a general overcurrent to be cut off at a zero relay (ZR) and a molded case circuit breaker (MCCB). It is effective to prevent the problem that the magnetic contactor (MC) is burned when the instantaneous large current is tripped to the magnetic contactor MC by the control of the existing EOCR by detecting and selectively tripping the large instantaneous current. In addition, the zero relay controller has the effect of preventing accidents in advance by controlling various other visualization lamps, alarm alarms, and smart viewers that display time difference flashing according to the cause of the trip when the wiring breaker or the zero relay is selectively tripped. .

The motor control panel system equipped with a digital zero relay controller according to the present invention uses an input coil, a trip coil, and a zero relay (ZR) equipped with a permanent magnet to apply power to the input coil at the fixed terminal. Even if the power supplied to the terminal is cut off, the movable terminal and the fixed terminal are kept in contact by the magnetic force of the permanent magnet, thereby minimizing standby power consumed during operation. In addition, by maintaining the contact state with a permanent magnet, there is an effect of solving power quality problems such as preventing instantaneous power failure due to vibration of the contact.

In addition, since the CT embedded in the wiring breaker detects and acquires current information of overcurrent or instantaneous large current, there is an effect that there is no need to incorporate a separate CT into the digital zero relay controller. In addition, there is an advantage in that wiring for tripping of a wiring breaker is easier compared to an external CT of a conventional wiring breaker.

1 is a view showing a motor control panel system equipped with a digital zero relay controller according to the present invention.
2 is a cross-sectional view of a zero relay (ZR) of a motor control panel system equipped with a digital zero relay controller according to the present invention.
3 is a D-ZRC block diagram of a motor control panel system equipped with a digital zero relay controller according to the present invention.

The terms or words used in the present specification and claims are not limited to their usual or dictionary meanings and should not be interpreted, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. Based on the principle that there is, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all the technical spirit of the present invention, so that they can be replaced at the time of application. It should be understood that there may be various equivalents and variations.

Hereinafter, a motor control panel system equipped with a digital zero relay controller according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram of an electric motor control panel system equipped with a digital zero relay controller according to the present invention.

As shown in FIG. 1, the motor control panel system equipped with a digital zero relay controller according to the present invention includes a wiring breaker (MCCB <Molded Case Circuit Breaker>:100), a zero relay (ZR<Zero Relay>:200), and D- It includes a ZRC (Digital-Zero Relay Controller <digital zero relay controller>: 300) and an electric motor 400.

The wiring breaker 100 receives power from a power facility such as an external telephone pole through a three-phase distribution line to supply a current drawn to the load on the output side, while supplying current when a current higher than the set current is supplied to the load. Block it.

In particular, the wiring breaker 100 has an arc extinguishing chamber capable of blocking a line while a load current flows.

In addition, the distribution breaker 100 has a single-phase or two CT (Current Transformer) built-in, more specifically, of the three phases wired to the distribution breaker 100, the first CT ( 110) and the second CT 120 measure overcurrent and instantaneous large current.

Here, the overcurrent refers to a current set in advance so that the zero relay (ZR:200) can be cut off in order to prevent the motor from being burned out due to an overload or the like as the rated current is higher than the rated current during operation of the motor.

The instantaneous large current refers to a current set in advance so that the wiring breaker 100 can be cut off in order to prevent the zero relay 200 from being burned due to a large current, an arc current, or a short-circuit current more than the normal motor starting current.

In FIG. 1, the CT is shown as being formed on the R phase and the T phase, but the present invention is not limited thereto, and the CT may be formed on any two or single phases of the R, S, and T phases.

The two first CTs 110 and the second CTs 120 mounted in the distribution circuit breaker 100 are Permalloy CTs, with an accuracy of 0.5A×1% and an overcurrent flowing in the R and T phases and instantaneous Measure large current.

Compared to the external CT, the built-in CT facilitates external wiring for tripping of the wire breaker 100, and the current information measured in the built-in CT of the wire breaker 100 is used as it is D-ZRC (Digital Zero Relay Controller). The ZRC 300 has the advantage of not having to have its own CT.

As shown in FIG. 2, the zero relay 200 includes an input coil 210, a trip coil 220, a fixed terminal 230, a movable terminal 240, a permanent magnet 250, an iron core 260, and a rod. Includes 270.

The operation of the zero relay 200 having the configuration as described above will be described.

First, in order to connect the fixed terminal 230 and the movable terminal 240 to supply power to the load, external power is supplied to the input coil 210 so that the end of the iron core 260 facing the permanent magnet 250 corresponds to By making the permanent magnet 250 and the opposite polarity, the permanent magnet 250 is pulled toward the iron core, and when the rod 270 installed with the movable terminal 240 is pulled as the permanent magnet 250 is pulled in this way, the movable terminal 240 is in contact with the fixed terminal 230.

At this time, even if the supply of external power to the input coil 210 is blocked, an attractive force with the end of the iron core 260 acts by the magnetic force of the permanent magnet 250, and the movable terminal 240 And the fixed terminal 230 remain in contact with each other.

That is, as described above, the present invention is a state in which the movable terminal 240 and the fixed terminal 230 are in contact with the magnetic force of the permanent magnet 250 itself even when the supply of external power to the input coil 210 is cut off. It can be maintained to prevent the occurrence of standby current due to continuous supply of external power.

Conversely, external power is supplied to the trip coil 220 in order to trip the connection between the fixed terminal 230 and the movable terminal 240 to cut off the power supplied to the load, and the permanent magnet ( The end facing 250) is made to have the same polarity as the corresponding permanent magnet, and the permanent magnet 250 is pushed in the opposite direction of the iron core 260 by a repulsive force, so that the permanent magnet 250 is pushed. As the rod 270 including the movable terminal 240 is pushed, the connection between the fixed terminal 230 and the movable terminal 240 is tripped.

The D-ZRC 300 receives the current information measured by the CT built in the wiring breaker 100 and the voltage information of the three-phase line between the wiring breaker 100 and the zero relay 200 and The circuit breaker 100 and the zero relay 200 are controlled.

More specifically, the D-ZRC 300 is a measurement current information receiving unit 310, a measurement voltage information receiving unit 320, a current & voltage setting unit 330, a time setting unit 340, as shown in FIG. , And a control unit 350.

The measurement current information receiving unit 310 receives measurement current information measured by the first CT 110 and the second CT 120 built in the distribution breaker 100.

The measured voltage information receiving unit 320 is connected to a three-phase line wired from the wiring breaker 100 to the zero relay 200 to directly measure the voltage of the line to collect information, or on the three-phase line Each voltage sensor may be formed to receive information measured by the corresponding voltage sensor.

According to a user's manipulation, the current & voltage setting unit 330 sets the size of the current value required to determine whether the current input to the motor is an overcurrent or an instantaneous large current.

In addition, the current & voltage setting unit 330 is a reference voltage required for opening and closing of the electric motor 400 in order to determine a low voltage, an overvoltage, or a phase loss of a line wired from the wiring breaker 100 to the zero relay 200 Set the value.

In addition, the current & voltage setting unit 330 sets a reference current value for determining an instantaneous large current of an electric motor wired from the wiring breaker 100 to the zero relay 200.

The instantaneous high current generally exceeds the motor starting current [(6 to 8 times the operating current) and includes an arc current, a short-circuit current, and the like.

The D-ZRC 300 stops the trip signal of the zero relay 200 when the current value input to the motor exceeds the instantaneous high current value preset in the current & voltage setting unit 330, and only the wiring breaker 100 By outputting the trip signal, it is possible to prevent burnout of the zero relay 200 having no arc extinguishing blocking capability.

In general, when the current & voltage setting unit 330 is used for a limited time to block the zero relay 200, the current value is 110 to 120% of the operating current when the motor is operated under a normal load after the start of the motor is completed. Is set.

In addition, according to the user's manipulation, the current & voltage setting unit 330 can set 130%, 150%, 170% and 200% of the operating current when used in inverse time to block the zero relay 200, It is not limited thereto, and can be set in various percentages.

The time setting unit 340 is set so that the wiring breaker 100 is immediately cut off when a large instantaneous current is sensed.

In addition, the time setting unit 340 is configured to set the starting time of the electric motor to prevent misunderstanding of detecting and shutting off an overcurrent generated when the electric motor is started.

In addition, the time setting unit 340 may set the trip time of the zero relay 200 to correspond to 130%, 150%, 170%, and 200% of the operating current set by the current & voltage setting unit 330. have.

At this time, the time setting unit 340 may set the trip time in a short time in inverse proportion to the percentage size of the operating current in consideration of the inverse time point. For example, in the case of 130% of the operating current, the trip time is 10 seconds or 150%. If the current increases continuously in 3 seconds in the case of 3 seconds, 1 second in the case of 170%, and 0.1 second in the case of 200%, the trip time of the zero relay 200 may be set to rapidly shorten.

In addition, the time setting unit 340 may also set a time for a set voltage for determining overvoltage and undervoltage through the current & voltage setting unit 330.

The control unit 350 receives and analyzes the measured current information received by the measured current information receiving unit 310, and the measured current is the size of the set current set through the current & voltage setting unit 330 and the time setting unit Considering the set time set through (340), it is judged as overcurrent or instantaneous large current.

More specifically, the control unit 350 is a wiring breaker when the measured current exceeds the preset current set through the current & voltage setting unit 330 and exceeds the set time set through the time setting unit 340. The zero relay 200 is selected among 100 or the zero relay 200 and is determined as a blocking current to be blocked.

In addition, in the time setting unit 340, the blocking standby time is set to a limited time (definite or inverse), but for instantaneous high current blocking, the blocking standby time is set to immediate, so the control unit 350 performs the measurement. When the current is greater than the instantaneous high current, the wiring breaker 100 is first selected among the wiring breaker 100 or the zero relay 200 and is determined as a blocking current to be blocked.

For example, when the measured current momentarily indicates an overcurrent state at a certain time corresponding to several tens of ms without a special time delay, the control unit 350 determines it as an instantaneous large current.

In addition, the control unit 350 determines the magnitude of the overcurrent when the measured current is an overcurrent equal to or greater than a predetermined percentage of the operating current, such as 130%, 150%, 170%, and 200% set through the current & voltage setting unit 330. It is analyzed as an overcurrent with an inverse time characteristic that must be tripped with an inversely proportional length of time.

Meanwhile, the control unit 350 receives the measured voltage information received by the measured voltage information receiving unit 320 and determines whether the measured voltage is a low voltage, an overvoltage, or a phase loss.

That is, when the measured voltage is higher than the set voltage set through the current & voltage setting unit 330, the control unit 350 continues the zero relay ( 200) is judged as an overvoltage to be blocked.

In addition, when the measured voltage is lower than the set voltage set through the current & voltage setting unit 330 continues for more than a time set through the time setting unit 340, the zero relay ( 200) is judged as a low voltage to be blocked.

On the other hand, the control unit 350 calculates the measured voltage deviation, that is, the voltage deviation between three phases, and if the deviation is more than 38%, determines that the voltage phase is formed, and calculates the measured current deviation, that is, the current deviation between three phases, so that the current deviation between phases is If it is 85% or more, it is determined as a deviation to be blocked by the zero relay 200 as a current phase formation.

To explain the implementation process as an example, in the D-ZRC 300 according to the present invention, the user sets the magnitude of the overcurrent in the current & voltage setting unit 330 and the cutoff time in the time setting unit 340 . In addition, the control unit 350 determines the current blocked by the zero relay 200 as an overcurrent when the overcurrent exceeds the set current and the set time elapses while the measured current is always detected, and drives the trip coil of the zero relay 200. Control.

The D-ZRC 300 according to the present invention is in a state of constantly sensing the current measured from the built-in CT of the wiring breaker. The D-ZRC 300 not only has a current measurement information receiving unit 310 including an AD converter that converts the analog current input from the wiring breaker into a digital current, but also the control unit 300 of the D-ZRC 300 It includes a determination unit to determine whether a current to open and close the zero relay and a determination unit to determine whether or not the current to cut off the wiring breaker.

The determination unit to determine whether or not the current to open and close the zero relay of the control unit 350 according to the present invention is equal to or greater than the current value measured from the built-in CT of the wiring breaker over the overcurrent cutoff current value preset in the current & voltage setting unit 330. If it is determined that the control unit 350 outputs a zero relay trip signal, and when it is determined that the current value exceeding the instantaneous current set in advance by the current & voltage setting unit 330 is determined, the control unit 350 is the zero relay 200 The zero relay 200 is prevented from being burned by not outputting the trip signal of.

In addition, the determination unit to determine whether the current to cut off the wiring breaker 100 of the control unit 350 is the current value measured from the built-in CT of the wiring breaker 100 is the instantaneous current value previously set by the current & voltage setting unit 330 When it is determined that the value exceeds, the control unit 350 outputs a trip signal only to the wiring breaker 100 to prevent burnout of the zero relay 200.

Furthermore, by setting the trip setting time of the wiring breaker 100 immediately (for example, within 50 msec) in the time setting unit, and setting a time difference for the overcurrent of the definite or inverse time to be blocked by the zero relay 200 (e.g., 100 msec ) It is also possible to sequentially shut off the wiring breaker 100 and the zero relay.

In this way, the zero relay 200 is destroyed from the arc by tripping the wiring breaker 100 in a binary method or by selectively tripping the zero relay 200 so that the zero relay 200 does not block the instantaneous high current. There is an effect that can prevent it.

As a result, the D-ZRC 300 analyzes the current information collected from the first CT and the second CT respectively formed on any two of the single-phase or three-phase wired to the wiring breaker 100 to provide an overcurrent lower than the instantaneous large current. When is detected, the zero relay 200 is selectively tripped after a predetermined period of time, and when a current exceeding the instantaneous high current is detected, the output of the trip signal of the zero relay does not occur, so only the wiring breaker 100 is selected. To prevent burnout of the zero relay 200 by tripping.

Finally, the motor control panel system equipped with a digital zero relay controller according to the present invention may further include a smart viewer 500 that is controlled by the D-ZRC 300 to display a trip state.

The smart viewer 500 is formed on the front of the motor control panel door to cause a corresponding trip when the wiring breaker 100 or the zero relay 200 trips due to instantaneous high current, overcurrent, low voltage, overvoltage, phase loss, etc. It displays various different visualization lamps, alarm alarms, and time difference flashing accordingly.

More specifically, the smart viewer 500 separates the trips of the wiring breaker 100 and the zero relay 200 in a dual trip structure, displays a visualization lamp in different colors, and causes the zero relay 200 to trip. Visualization lamps are displayed in different colors by further subdividing them according to (overcurrent, undervoltage, overvoltage, phase loss).

That is, the smart viewer 500 is composed of a light-emitting device such as an LED, receives separate driving power, and emits light of a different color according to the cause of the trip to be displayed.

In the above, the technical idea of the present invention has been described together with the accompanying drawings, but this is illustrative of a preferred embodiment of the present invention and does not limit the present invention. In addition, it is obvious that any person of ordinary skill in the technical field to which the present invention pertains can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

100: wiring breaker
200: zero relay
300: D-ZRC
310: measurement current information receiver
320: measurement voltage information receiver
330: current & voltage setting unit
340: time setting unit
350: control unit
400: electric motor

Claims (8)

A wiring breaker having a built-in CT for measuring current and receiving power to an input side through a distribution line, transmitting power to a load on the output side, and blocking the supply of current according to the state of the current supplied to the load;
Depending on the state of the current or voltage supplied from the distribution breaker to the final load, the relay is turned on (ON) and off (OFF) by the control of the digital zero relay controller (D-ZRC), and the relay on (ON) state is a permanent magnet. A zero relay (ZR) in which standby power generated by the magnetic force of the alternating current electromagnet becomes zero by being maintained by the magnetic force of ZR;
Digital zero relay that collects and analyzes current information from the CT built in the wiring breaker and voltage information from the input terminal of the zero relay, and selectively trips the wiring breaker or zero relay based on the analysis information to cut off the current supply Controller (D-ZRC); And
Including; an electric motor that is a final load operated by driving of the wiring breaker or the zero relay
The D-ZRC is
A time setting unit that presets the trip time of the wiring breaker to be shorter than the trip time of the zero relay,
The time setting unit may set the starting time of the motor, and set a trip time inversely proportional to the percentage size of the driving current,
The control unit of the D-ZRC
A determination unit that determines whether a current to open and close the zero relay and a determination unit to determine whether or not a current to cut off the wiring breaker,
When the determination unit for determining whether the current to open and close the zero relay determines that the current value measured from the built-in CT of the wiring breaker is equal to or greater than the overcurrent cutoff current value preset in the current & voltage setting unit, the control unit outputs a zero relay trip signal. And, if the current & voltage setting unit determines that the current value exceeds the preset instantaneous current, the control unit does not output the trip signal of the zero relay,
If the determination unit that determines whether the current to cut off the wiring breaker determines that the current value measured from the built-in CT of the wiring breaker exceeds the instantaneous current value preset in the current & voltage setting unit, the control unit sends a trip signal only to the wiring breaker. A motor control panel system equipped with a digital zero relay controller, characterized in that outputting.
The method of claim 1,
The D-ZRC further comprises a wiring breaker or a smart viewer visually distinguished from each other according to a corresponding trip cause when the zero relay is selectively tripped, and controls the motor control panel system with a digital zero relay controller.
The method of claim 1,
The D-ZRC is
In the case of detecting a current exceeding the instantaneous high current by analyzing the current information collected from the first CT and the second CT respectively formed on any two of the single-phase or three-phase wired to the wire breaker, among the wire breaker and the zero relay, the A motor control panel system equipped with a digital zero relay controller, characterized in that the wiring breaker is tripped to prevent burnout of the zero relay.
The method of claim 1
The D-ZRC is
Digital characterized in that, when overcurrent or current phase-out is detected by analyzing the current information, or when undervoltage, overvoltage, or voltage phase-out is detected by analyzing the voltage information, the zero relay is selected and tripped from among the wiring breaker and the zero relay. Motor control panel system with zero relay controller.
The method of claim 1,
The D-ZRC is
When an overcurrent lower than an instantaneous high current is detected by analyzing the current information collected from the first CT and the second CT respectively formed on any two of the single phase or the three phase wired to the wiring breaker, the zero relay is selectively tripped. And, when detecting a current exceeding the instantaneous high current, the wiring breaker is selectively tripped to prevent burnout of the zero relay.
The method of claim 1
The zero relay is
Including input coil, trip coil, fixed terminal, movable terminal, permanent magnet, iron core, and rod,
When receiving the input signal from the D-ZRC, external power is supplied to the input coil so that the end of the iron core toward the permanent magnet has the opposite polarity to the permanent magnet, and the movable terminal is fixed by an attractive force. When contacting a terminal, even if the supply of external power to the input coil is cut off, the movable terminal and the fixed terminal remain in contact with each other by the magnetic force of the permanent magnet, so that the movable terminal remains in contact with the fixed terminal. Motor control panel system equipped with a digital zero relay controller, characterized in that to remove the standby current for.
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