KR101104559B1 - Burnout prevention motor starting circuit - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor starting circuit for preventing burnout, and in particular, in a motor starting circuit including a low / high pressure starting reactor and a current transformer (Current Transformer, CT) installed in each bus by three phases (RST). A first current transformer provided on the secondary side R of the current transformer, a second current transformer provided to collectively penetrate three phases (RST) at a power supply stage of the starting reactor, and a phase and the first phase detected by the first current transformer. It is characterized in that it comprises a fault detector for comparing the current phase detected by the two current transformers to determine whether or not the phase difference occurs to detect the fault / normal state of the starting reactor.
Accordingly, the present invention detects a failure due to a poor contact of the short-circuit contactor and the opening of the secondary side of the instrument current transformer by using a current phase difference to accurately discriminate between a normal operation state or an abnormal operation state to start a reactor and an instrument current transformer. Not only to prevent damages, but also to prevent accidents in advance, and to minimize damage caused by damage to or damage to facilities and peripherals, to maximize the utilization rate of facilities, and to reduce mental and economic burden on maintenance of facilities. Can be.

Description

Motor maneuver circuit for prevention of damage by a fire}

The present invention relates to a motor starting circuit for preventing burnout, and more particularly, by detecting a failure due to a poor contact of a short-circuit contactor using a current phase difference, and opening of a secondary side of a current transformer for an instrument, to prevent burnout of parts. It relates to a motor starting circuit for preventing burnout that can be prevented in advance.

In general, a motor starting reactor reduces terminal voltage to a motor when starting an induction motor, and as the starting proceeds and the terminal voltage increases as the current decreases, and the acceleration gradually increases, the reactor is short-circuited without opening the power completely. It can be connected by voltage, eliminating the difficulties of inrush current, simplifying operation, and ensuring complete prevention of abnormal current.

The cause of burnout of the starting reactor installed for the purpose of starting the motor may be caused by a poor contact of the shorting contactor contact that short-circuits the starting reactor, or in the case of a high-voltage starting shorting contactor, when the contactor is not in the normal closing position, After the engine is started, an accident occurs because the starting reactor cannot be shorted.

On the other hand, when the secondary circuit is opened, the instrument current transformer (C.T) is burned out, and the instrument current transformer (C.T) is saturated with magnetic flux, and high pressure is generated on the secondary side.

Such starting reactors are manufactured at a short time use rating (1 minute, 3 minutes, 5 minutes) at the time of manufacture. Therefore, when the motor load current is continuously supplied through the starter reactor winding due to poor contact of the short circuit contactor, the burner is burned out, and the starter reactor is burned out, which causes power outages, burnout of peripheral devices, and fire accidents. do.

Conventionally, the voltage and current required for initial start-up of a three-phase motor operated with high voltage and high current are consumed 5 to 7 times as much as normal power, and the initial drive is performed. And a reactor for limiting current is installed, and a measuring device is connected between the power supply and the reactor to detect a failure by measuring a voltage and a current changed when the reactor fails.

1 is a circuit diagram of a motor starting board using a low / high pressure starting reactor according to a first embodiment of the prior art.

Referring to FIG. 1, a motor starting panel according to a first embodiment of the prior art includes a voltage transformer terminal PT connected to a three-phase power source RST and a voltage test terminal PTT, which is a test terminal of the instrument transformer. Test Terminal), VCB (Vacuum Circuit Breaker) which is a high voltage breaker, surge absorber (SA) installed on the load side of the VCB terminal and protecting the device by absorbing open / close surge, and phase loss and leakage of motor ZCT (Zero Current Transformer) for converting three-phase current into a primary current to detect the current, the current transformer (Current Transformer, CT) installed for each phase (RST) on the line, and Current test terminal (CTT), which is a test terminal, a motor protector which is connected to a circuit for supplying electric power to the motor (M) and protects the motor, and a low / high pressure starting reactor (11). ) And a short circuit contactor 12.

However, the starter reactor 11 according to the prior art has a problem that a burnout accident occurs because there is no device that can protect the starter reactor 11 even when a short-circuit contactor 12 occurs.

2 is a circuit diagram of a motor starting board using a low / high pressure starting reactor according to a second embodiment of the prior art.

  As shown in FIG. 2, the motor starting panel according to the second embodiment of the prior art includes PT, PTT, VCB, ZCT, CT, CTT, a motor protection device, a starting reactor 21, a shorting contactor 22, And a temperature sensing sensor 23 attached to the winding of the starting reactor 21.

In this way, the temperature sensing sensor 23 is attached to the winding or the iron core of the starting reactor 21 to detect the starting reactor 21 which is equal to or higher than a set temperature to determine whether the failure occurs.

By the way, the motor starting panel according to the second embodiment of the prior art requires a delay time until the temperature sensor 23 rises to a temperature, thereby performing a protective operation after deterioration of the starting reactor 21 proceeds. There is a problem that the service life of the 21 can be shortened, and the fault phase PHASE of the short-circuit contactor 22 can not be determined.

Accordingly, an object of the present invention is to prevent failure due to a poor contact of the short-circuit contactor by using a current phase difference, and to protect the current transformer for the instrument by detecting the opening of the secondary side of the instrument current transformer to prevent damage to parts It is to provide a motor starting circuit for preventing burnout that can prevent an accident in advance.

In order to achieve the above object of the present invention, a burnout prevention motor starting circuit according to the present invention includes a motor including a low / high pressure starting reactor and a current transformer (Current Transformer, CT) installed at each three phase (RST) in a bus bar. A starter circuit comprising: a first current transformer provided on the secondary side R of the instrument current transformer, a second current transformer provided to collectively penetrate three phases (RST) to a power stage of the starting reactor, and the first current transformer. And a fault detector for detecting a fault / normal state of the starting reactor by determining whether a phase difference occurs by comparing the phase detected by the current transformer and the current phase detected by the second current transformer.

At this time, a third current transformer is installed on the secondary side of the current transformer for the instrument, and the third current transformer is installed so that the fault detector compares the current phase detected by the first current transformer with the current phase detected by the third current transformer. When it occurs, it is determined that the secondary of the current transformer for the instrument is in an open state, and short-circuits the open phase and transmits an alarm and a blocking signal.

The fault detector may include a power input port to which power is input, a first sensor input port to which a signal of a reference current sensor is input, a second sensor input port to which a signal of a reactor current sensor is input, and a current transformer for the instrument ( CT) A third sensor input port to which a signal of the current sensor is input, a communication port for transmitting and receiving data, a first output port for outputting a fault signal of the current transformer for the instrument, and a fault signal for the reactor. And a data input port to which respective switching signals of the start switch ST, the rotary switch RS, and the field switch FS are input.

The fault detector is a steady state because the phase difference does not occur when the reference current phase detected by the first current transformer and the secondary current phase of the second current transformer are compared when the shorting contactor of the starting reactor is in a normal state. When the short-circuit contactor is in an abnormal state and compares the reference current phase detected by the first current transformer with the secondary current phase of the second current transformer, a constant phase difference occurs according to a failure type. It is characterized by determining that the failure state and sending out alarm and blocking signals.

On the other hand, in the fault detector, when the secondary of the instrument current transformer is not opened and is in a normal state, the sum of the secondary current vector of the third current transformer is 0, and the reference current phase and the third current transformer detected by the first current transformer are zero. Comparing the secondary side current phase of the phase difference does not occur it is determined that the steady state.

According to the burnout prevention motor starting circuit as described above, the fault is caused by a poor contact of the short-circuit contactor by using the current phase difference, and the secondary side opening of the current transformer for the instrument is detected to accurately distinguish the normal operating state or the abnormal operating state and start it. It is effective to prevent burnout of reactor and instrument current transformer, and to prevent accidents in advance.

Therefore, the present invention has the effect of minimizing damage due to damage or fire of facilities and peripheral devices to maximize the operation rate of facilities, and reduce a lot of burdens mentally and economically on maintenance of facilities.

1 is a circuit diagram of a motor starting board using a low / high pressure starting reactor according to a first embodiment of the prior art;
2 is a circuit diagram of a motor starting board using a low / high pressure starting reactor according to a second embodiment of the prior art;
3 is a circuit diagram of a burnout prevention motor starting circuit according to an embodiment of the present invention;
4 is a view showing the appearance of a failure detector according to an embodiment of the present invention;
5 is a graph showing the normal current of the short-circuit contactor and the secondary side current of the second current transformer according to an embodiment of the present invention,
6 is a graph showing a reference current at the phase R failure of the short-circuit contactor and the secondary current of the second current transformer according to an embodiment of the present invention;
7 is a graph showing a reference current at the S phase failure of the short-circuit contactor and the secondary current of the second current transformer according to an embodiment of the present invention,
8 is a graph showing a reference current and a secondary current of a second current transformer in a T phase failure of a short-circuit contactor according to an embodiment of the present invention;
9 is a graph showing a reference current and a secondary current of the second current transformer when the RS phase failure of the short-circuit contactor according to the embodiment of the present invention;
10 is a graph showing the reference current and the secondary current of the second current transformer during the ST phase failure of the contactor for a short circuit according to an embodiment of the present invention,
11 is a graph showing the reference current and the secondary side current of the second current transformer in the RT phase failure of the short-circuit contactor according to an embodiment of the present invention,
12 is a graph showing the secondary normal current and the secondary current of the third current transformer of the instrument current transformer according to an embodiment of the present invention,
13 is a graph showing a reference current at the R phase opening and a secondary current of the second current transformer of the instrument current transformer according to the embodiment of the present invention;
14 is a graph showing the reference current at the S phase opening of the instrument current transformer and the secondary current of the second current transformer according to an embodiment of the present invention,
15 is a graph showing a reference current at the T phase opening and a secondary current of the second current transformer of the instrument current transformer according to the embodiment of the present invention;
16 is a graph showing a reference current at the opening of the RS phase of the instrument current transformer according to an embodiment of the present invention and a secondary current of the second current transformer;
FIG. 17 is a graph illustrating a reference current at opening ST phase and a secondary current of a second current transformer in an instrument current transformer according to an embodiment of the present invention; FIG.
18 is a graph showing a reference current at the RT phase opening and a secondary current of the second current transformer of the instrument current transformer according to the embodiment of the present invention;

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals are used for like elements in describing each drawing.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. Hereinafter, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

3 is a circuit diagram of a burnout prevention motor starting circuit according to an embodiment of the present invention, Figure 4 is a view showing the appearance of a failure detector according to an embodiment of the present invention.

3 and 4, the burnout prevention motor starting circuit according to an embodiment of the present invention, the instrument transformer PT connected to the three-phase power supply (RST), and the test terminal of the instrument transformer (PT) Potential Test Terminal (PTT), Vacuum Circuit Breaker (VCB) which is a high voltage breaker, and Surge Absorber (SA) installed on the load side of the VCB terminal to protect the device by absorbing open / close surge. In addition, a zero-phase transformer (ZCT) converts three-phase current into a primary current to detect phase leakage and leakage on the motor (M) side, and a current transformer (Current) installed for each phase (RST) on the bus. A motor protection device connected to a transformer, a CT, a current test terminal (CTT), which is a test terminal of the instrument current transformer (CT), and a circuit for supplying power to the motor (M) to protect the motor. (Motor Protector) 200, low / high pressure reactor 100, and short circuit And a contactor (110).

In particular, the burnout prevention motor starting circuit according to the embodiment of the present invention includes a first current transformer CT1 installed on the secondary side R of the current transformer CT for power supply, and a power supply stage of the starting reactor 100. A second current transformer CT2 installed to collectively penetrate the phase RST, a third current transformer CT3, and the first current transformer CT1 so that a three-phase collectively penetrates the secondary side of the instrument current transformer CT; By comparing the phase detected by the current and the current phase detected by the second current transformer (CT2) to determine whether or not a phase difference occurs by detecting a fault / normal state of the starting reactor (100), the first current transformer (CT1) By comparing the detected current phase and the current phase detected by the third current transformer CT3, it is determined that the secondary of the current transformer CT for the instrument is open when a phase difference occurs. A failure detector 300 for transmitting a signal is included.

At this time, the failure detector 300, as shown in Figure 4, the power input port 301, the AC 220V power is input, the first sensor input port 302, the signal of the reference current sensor is input, A second sensor input port 303 to which a signal of the reactor current sensor is input, a third sensor input port 304 to which a signal of the CT current sensor for the instrument is input, and data transmission through RS485 communication; A communication port 305 in charge of reception, a first output port 306 having terminals of COM1, R, S, and T for outputting a fault signal of the current transformer CT of the instrument, and the starting reactor 100 The second output port 307 having the terminals of COM2, R, S, and T, and the respective switching signals of the start switch ST, the rotary switch RS, and the field switch FS to output the fault signal of And a data input port 308.

Hereinafter, the operation of the burnout prevention motor starting circuit according to the embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

5 to 18, the burnout prevention motor starting circuit according to an embodiment of the present invention is installed by the first current transformer (CT1) of the clamp type on the secondary side R of the instrument current transformer (CT) to start the reactor 100 At the time of detecting the failure of the short-circuit contactor 110 and the secondary opening of the instrument current transformer CT, the failure detector 300 is used as a reference signal for failure determination.

In addition, by integrating three phases into the power supply terminal of the starting reactor 100 so as to pass through one second current transformer CT2 collectively, the failure detector 300 secondary opening of the current transformer CT for instrumentation. To be detected.

That is, when the short circuit contactor 110 is normal, the secondary current vector sum of the second current transformer CT2 becomes zero, and the fault detector 300 detects the first current transformer CT1. Comparing the reference current phase with the current phase detected by the second current transformer CT2, it is determined that a phase angle difference does not occur and thus, it is determined that it is a steady state.

By the way, when the one-phase or two-phase failure occurs in the short-circuit contactor 110, since the secondary current of the second current transformer CT2 is not equal to zero of the three-phase current vector, the first current transformer CT1. Comparing the reference current phase detected by the reference current and the secondary current phase of the second current transformer CT2, a phase angle difference occurs depending on the type of failure, thereby accurately determining the failure phase of the short-circuit contactor 110. To shut off alarms and breakers.

On the other hand, by installing a third current transformer (CT3) through a three-phase package through the secondary side of the current transformer CT for the instrument so that the failure detector 300 can detect the secondary opening of the current transformer CT for the instrument. .

 When the secondary of the current transformer CT for the fault is not open, the failure detector 300 has a secondary current vector sum of the third current transformer to be zero, but the secondary side of the current transformer CT for the instrument is zero. In this case, when the reference current phase detected by the first current transformer CT1 and the secondary current phase of the third current transformer CT3 are compared, a phase angle difference does not occur, and thus, it is determined that the state is normal.

 On the other hand, the fault detector 300 is the second current vector sum of the third current transformer (CT3) is not zero, if one phase or two phases of the secondary of the current transformer CT for the instrument is open, Comparing the reference current phase detected by the first current transformer CT1 with the secondary current phase of the third current transformer CT3, a difference in phase angle occurs according to a failure type, and thus the secondary current of the current transformer CT for the instrument is generated. The open phase (PHASE) can be detected to short the secondary open phase (PHASE) and shut off the alarm and breaker.

In the above, the burnout prevention motor starting circuit according to an embodiment of the present invention may selectively install the second current transformer CT2 and the third current transformer CT3 in a state where the first current transformer CT1 is installed. Both the second current transformer CT2 and the third current transformer CT3 may be installed.

First, FIGS. 5 to 11 show current graphs when the failure detector 300 determines the failure of the short-circuit contactor 110 of the starting reactor 100. 5 to 11, the red line represents the secondary side current of the second current transformer CT2 and the blue line represents the secondary side current of the bus line R, respectively.

(A) Normal operation of the starting reactor 100

 When the start is completed and normal operation, no current is formed at the short-circuit contact of the short-circuit contactor 110, so that no current is formed at the secondary side of the second current transformer CT2, and thus the instrument detected by the first current transformer CT1. Only the R phase reference current of the CT is shown (see FIG. 5).

(B) Short circuit contactor 110 failure type

    (1) Poor contact between 1 phase and 2 phase (PHASE) among 3 phases (PHASE)

The driving current of the motor M is supplied through the starting reactor 100 of the contact failure (meaning that the resistance is large) phase PHASE. At this time, the current of the motor is supplied through the short-circuit contactor contact, but the current flowing in the contact failure phase (PHASE) is not a three-phase equilibrium current, so the second current transformer (CT2) ), The vector synthesized current is detected.

The fault current phase of the short-circuit contactor 110 is determined by measuring the phase of the current of the second current transformer CT2 and the secondary basic current of the third current transformer CT3 at the same time period. To FIG. 11)

Next, FIGS. 12 to 18 show graphs of currents when the failure detector 300 determines the secondary open state and the failure of the current transformer CT. 12 to 18, the red line represents the secondary side current of the third current transformer, and the blue line represents the secondary side current on the bus line R, respectively.

(A) Normal of secondary side of instrument current transformer (CT)

Since no current is formed at the secondary side of the third current transformer CT3, only the R phase reference current of the current transformer CT for the instrument detected by the first current transformer CT1 is displayed.

(B) Secondary side opening of CT

If the instrument current transformer CT is any one of R phase, S phase, T phase, RS phase, ST phase, and RT phase, the secondary current vector sum of the third current transformer CT3 is not zero. Comparing the reference current phase detected by the first current transformer CT1 with the secondary current phase of the third current transformer CT3, it can be seen that a constant phase difference occurs according to a failure type.

As described above, the fault detector 300 detects a secondary current failure of the short-circuit contactor 110 and the instrument current transformer CT by the first current transformer CT1 and the second current transformer CT2 during abnormal operation. ) Or by comparing the secondary current phase of the third current transformer (CT3) can be accurately identified and discriminated.

That is, the failure detector 300 detects a contact incomplete state by electrically detecting whether the shorting contactor 110 has completely shorted the starting reactor 100 through the second current transformer CT2, and Accurately detects the secondary side opening state of the instrument current transformer CT through the third current transformer CT3 and automatically generates a system stop and alarm to prevent damage to the starting reactor 100 and the instrument current transformer CT. It is possible to protect the safety of the facility.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

The present invention relates to a motor starting circuit for preventing burnout, and more particularly, by detecting a failure due to a poor contact of a short-circuit contactor using a current phase difference, and opening of a secondary side of a current transformer for an instrument, to prevent burnout of parts. In addition to minimizing the risk of damage to the facility and peripherals, and minimizing the damage caused by fire, the motor start-up circuit for burnout prevention can maximize the operation rate of the facility and reduce the mental and economic burden on the maintenance of the facility. It is about.

CT: Current transformer for instrument CT1: Current transformer
CT2: third current transformer CT3: third current transformer
100: starting reactor 110: short circuit contactor
300: Fault Detector

Claims (5)

In a motor starting circuit including a low / high pressure starting reactor and a current transformer (Current Transformer, CT) installed in each of three phases (RST) on the bus bar,
A first current transformer installed on the secondary side R of the current transformer for the instrument;
A second current transformer installed to integrate the three phases (RST) into the power supply stage of the starting reactor and collectively penetrate therethrough;
Motor failure characterized by comparing the phase detected by the first current transformer and the current phase detected by the second current transformer to determine whether a phase difference occurs and detects a fault / normal state of the starting reactor Circuit. The method of claim 1,
A third current transformer is installed on the secondary side of the current transformer for the instrument to pass through a three-phase package;
The fault detector compares the current phase detected by the first current transformer with the current phase detected by the third current transformer, and determines that the secondary of the current transformer for the instrument is open when a phase difference occurs, and shorts an open phase. And an alarm and a cutoff signal for transmitting the motor. The method of claim 1,
The fault detector,
A power input port to which power is input,
A first sensor input port to which a signal of the reference current sensor is input;
A second sensor input port to which a signal of the reactor current sensor is input;
A third sensor input port to which a signal of a CT current sensor for instrument is input;
A communication port responsible for transmitting and receiving data,
A first output port for outputting a fault signal of the current transformer of the instrument;
A second output port for outputting a reactor failure signal;
And a data input port to which each switching signal of the start switch (ST), the rotary switch (RS), and the field switch (FS) is input. The method of claim 1,
The failure detector determines that the phase difference does not occur when the reference current phase detected by the first current transformer and the secondary current phase of the second current transformer are compared when the shorting contactor of the starting reactor is in a normal state. and,
When the short-circuit contactor is in an abnormal state, if the reference current phase detected by the first current transformer and the secondary current phase of the second current transformer are compared, a constant phase difference occurs according to a failure type, so that the short-circuit contactor is determined to be a fault state. And a burnout prevention motor starting circuit for transmitting an alarm and a cutoff signal. The method of claim 2,
The fault detector may have a reference current phase detected by the first current transformer and two of the third current transformer when the secondary current vector sum of the third current transformer is 0 when the secondary current of the instrument current transformer is not opened and is in a normal state. A motor starting circuit for preventing burnout, characterized in that it is determined that the phase difference does not occur when comparing the difference current phases.

Images