JPS62230374A - Controlling for motor - Google Patents

Abstract

PURPOSE:To shorten the recovery time of power supply by reclosing a switch, waiting the establishment of power supply after the recovery of instantaneous service interruption. CONSTITUTION:When an electromagnetic contactor 5 is closed and a power supply is interrupted under the state in which a motor 4 is operated, a service- interruption detecting signal S18 is outputted from l voltage comparison circuit 18. When the service interruption detecting signal S18 is transmitted over an arithmetic circuit 22, the arithmetic circuit 22 stops the output of a drive signal S22a, and releascs the electromagnetic contactor 5. When the service-intcrruption detecting signal S18 is transmitted over a timer circuit 20, on the other hand, the timer circuit 20 starts timing operation. When the power supply is recovered and the output of the service-interruption detecting signal S18 is stopped, thc arithmetic circuit 22 outputs the drive signal S22a when irstantaneous service interruption is decided from a timing signal S20 at that time. When the drive signal S22a and a permission signal S24 delaying a voltage establishment signal S19 are given, the electromagnetic switch 5 is reclosed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Field of Application) The present invention relates to a motor control device that restarts a power recovery motor in the event of a momentary power outage.

(Prior art) For example, in a plant where a large number of electric motors are installed as drive sources and are required to operate continuously, when a momentary power outage occurs due to a lightning strike, ground fault, short circuit accident, etc. in the power system, it is difficult to restore power. At the same time, it is necessary to return to the process before the instantaneous power outage so as not to affect the product.

For this reason, a control device is generally provided that restarts the motor by automatically restarting the switch, such as a magnetic contactor, in the main circuit of each motor after the power is restored. When the motor is restarted, the starting current causes a voltage drop in the power supply, making it impossible for the motor to obtain sufficient starting torque, resulting in the motor stalling, becoming stuck, and overheating. Furthermore, there is a risk that the power transformer may trip due to overcurrent, resulting in a permanent power outage.

For this reason, conventionally, the time-limited instantaneous time-limiting relay, which is energized by the secondary output, is similar to the instantaneous-operating time-return type instantaneous power failure detection time-limiting relay, which is energized by the secondary output of the control transformer that steps down the power supply voltage. A regulation that provides a return type voltage establishment detection time limit m, and an electric appliance, so that when a power outage occurs, the voltage establishment detection time limit relay operates if the power is restored within the set time until the instantaneous power failure detection time limit relay recovers. A control device is provided which energizes the excitation coil of the electromagnetic contactor to restart the electromagnetic contactor after a period of time has elapsed.

(Problems to be Solved by the Invention) In conventional control devices using time-limited relays, restarting after a momentary power outage is managed only by the time limit of the time-limited relay for voltage establishment detection, so the power supply voltage is not sufficient. Even if it is not established, there is a possibility that it will be re-introduced. In particular, the conventional control device described above divides a large number of motors into several groups and restarts them sequentially, so if there is a motor that takes a long time to start, it will be restarted at the next timing of this motor. There is a possibility that the power supply voltage is not established at the time of the electric motor, and in such a case, it is necessary to reset the time limit of the time limit relay for voltage establishment detection. In addition, with management based only on the time limit as described above, conversely, even if the power supply voltage is established, the re-energization will not be completed until the time limit of the time limit relay for voltage establishment detection has elapsed, reducing the recovery time. It is not possible to aim for Moreover, since the electromagnetic contactor, the time-limited relay for instantaneous power outage detection, and the time-limited relay for voltage establishment detection are each independent devices, there are variations in their release voltage and return voltage. In some cases, the time-limited relay does not return due to the residual voltage of the secondary output, and the electromagnetic contactor remains closed without being released, causing a problem in which the control device is unable to perform the time-reset function.

Therefore, an object of the present invention is to be able to reliably restart after the delay time set when the power supply voltage is established, to shorten the recovery time after a momentary power outage, and to restart the delay time. An object of the present invention is to provide a control device for an electric motor that does not require any settings.

[Structure of the Invention] (Means for Solving the Problems) The motor control device of the present invention outputs a power failure detection signal when the detected voltage of the voltage detection means for detecting the power supply voltage of the motor becomes equal to or less than a set value. a second voltage comparison circuit that outputs a voltage establishment signal when the detected voltage exceeds a specified value; and a timer circuit that measures the output time of the power failure detection signal. , an arithmetic circuit is provided that outputs a drive signal when it is determined that a restart is necessary based on the time measured by the timer circuit, and when the voltage establishment signal is given, a permission signal is output after a delay time set by the arithmetic circuit has elapsed. A delay circuit for outputting the motor is provided, and a drive circuit is provided for re-closing a switch interposed in the main circuit of the motor when the drive signal is applied and the permission signal is applied. be.

(Function) In the electric motor control device of the present invention, when a power outage occurs, the timer circuit measures the power outage time based on the power outage detection signal from the first voltage comparison circuit, and the arithmetic circuit restarts the operation based on the result of the measured time. When it is determined that it is an instantaneous power outage, the power supply voltage is established by outputting a voltage establishment signal from the second voltage comparator circuit, and then after the delay time of the delay circuit has elapsed. The drive circuit causes the switch to close again, and the motors are restarted in the set order indicated by the delay time.

(Example) An example of the present invention will be described below with reference to the drawings.

First, the overall configuration will be described based on FIG. 1.
2 and 3 are three-phase main circuit busbars, one end of which is connected to a three-phase AC power source such as a power transformer, and the other end connected to a motor 4. And this main circuit busbars 1.2 and 3
An electromagnetic contactor 5, which is a switch, is interposed. 6 is a control transformer which is a voltage detection means, and its secondary coil 6
Both ends of the secondary coil 6b are connected to a portion of the main circuit bus 1.3 located closer to the power source than the electromagnetic contactor 5, and both ends of the secondary coil 6b are connected to the control bus 7.8. 9 is a control circuit, which has terminals 10 to 15. And terminal 1
0.11 is connected to the control bus 7.8, and the normally open auxiliary switch 5a and excitation coil 5b of the electromagnetic contactor 5 are connected between the control bus 7 and the terminals 12 and 13, respectively. A push button-shaped start switch 16 and a stop switch 17 are connected between the terminals 14 and 15, respectively.

Now, the configuration of the control circuit 9 will be described based on FIG. 18 is a first voltage comparator circuit, which is connected to terminal 10.
, 11, the voltage (detected voltage) between the control bus lines 7° and 8 is compared with a set value (set voltage), and when the detected voltage becomes less than the set voltage, a power failure detection signal SlB is output. . Reference numeral 19 denotes a second voltage comparison circuit, which compares the detected voltage with a specified value (specified voltage) and, when the detected voltage exceeds the specified voltage, outputs a voltage establishment signal S1. It is designed to output . In this case, the first voltage comparison circuit 1
The set voltage 8 is set to be smaller than the specified voltage of the second voltage comparison circuit 19 and larger than the release voltage of the electromagnetic contactor 5. Reference numeral 20 denotes a timer circuit, which, when the power failure detection signal S16 is applied, operates to measure time for the given time and outputs a measured time signal S20 indicating the content of the measured time. 21 is an input circuit having the terminals 12, 14 and 15, and when the auxiliary switch 5a, the start switch 16, or the stop switch 17 is turned on, a closed circuit state signal S, which is the on signal, is output.
5a, start command signal S16 or stop command signal S17
It is designed to output . 22 is an arithmetic circuit;
This is the aforementioned power failure detection signal S18. Clock time signal 320
+ It is configured to receive closed circuit state signals S, a, start command signal S16, and stop command signal SIT, and performs control operations such as calculations and judgments as described later based on the program stored in the storage circuit 23. drive signal S22
a and a delay time signal s22b. 24 is a delay circuit, which receives the delay time signal s22b and outputs the delay time signal s22b.
The delay time indicated by the contents of is set.
When the voltage establishment signal S19 is applied, the permission signal S24 is output after the set delay time has elapsed. Reference numeral 25 denotes a trigger circuit, which outputs an output signal S25 when the drive signal s22a and permission signal S2A is applied, and after outputting the output signal S26, outputs the permission signal 324. Even if the output signal S2S is stopped, output of the output signal S2S is continued, and when the output of the drive signals s, 2a is stopped, the output of the output signal $25 is stopped. Reference numeral 26 denotes an output circuit that constitutes the drive circuit 27 together with the trigger circuit 25. This has the aforementioned terminal 13, and when the output signal S2S is applied, it energizes the excitation coil 5b only while the output signal S2S is applied. It looks like this.

The control circuit 9 is equipped with a DC power supply circuit for obtaining DC power from the detected voltage applied between the terminals 10 and 11 and supplying it to each component circuit, and also has an auxiliary DC power supply circuit for backup in case of a power outage. It also has a power source.

Next, the operation of this embodiment will be explained.

Now, when the start switch 16 is turned on, the input circuit 21 outputs the start command signal 31B, which is the on signal, and gives it to the arithmetic circuit 22. The arithmetic circuit 22 receives a start command signal Sta.
When given, it outputs the drive signal 8221 and also outputs the delay time signal S22b having the content of the delay time rOJ. On the other hand, when the power supply voltage is established, the control buses 7 and 8 are the secondary outputs of the control transformer 6 that step down the power supply voltage.
The voltage between them, that is, the detected voltage has also been established (above the specified voltage), and therefore, the second voltage comparison circuit 19 outputs the voltage establishment signal S1 since the detected voltage is greater than the specified voltage. This voltage establishment signal S19 is given to the delay circuit 24, and the delay time of the delay circuit 24 is r
Since it is set to OJ, the delay circuit 24 immediately outputs the permission signal S24. As a result, since the trigger circuit 25 is given both the drive signal 522a and the permission signal S24, it comes to output the output signal S25, and in response, the output circuit 26 starts to energize the excitation coil 5b. , the electromagnetic contactor 5 is turned on and the electric motor 4 is started. Moreover, when the electromagnetic contactor 5 is turned on, the auxiliary switch 5a
is now turned on, and the input circuit 21 outputs the closed state signal S, a, which is the on signal, and gives it to the arithmetic circuit 22. ) is stored in the memory circuit 23.

Further, when the arithmetic circuit 22 is given the closed circuit state signal Ssa, it reads out the delay time rTJ stored in advance in the storage circuit 23 and generates a delay time signal s2 indicating the content of this delay time "T".
2b is output and applied to the delay circuit 24. Then, the delay circuit 24 outputs the delay time signal s22 in this way.
When b is given, a new delay time rTJ is set and the output of the permission signal 32m is stopped. Thereafter, when the stop switch 17 is turned on, the input circuit 21 outputs the stop command signal Sty, which is the ON signal, and supplies it to the arithmetic circuit 22. The arithmetic circuit 22 immediately stops outputting the drive signal S22a upon receiving the stop command signal SIT, and as a result, the trigger circuit 2
5 also stops outputting the output signal S2S, and the output circuit 26 turns off the current to the excitation coil 5b, thereby releasing the electromagnetic contactor 5.

On the other hand, as described above, when the power supply fails when the electromagnetic contactor 5 is turned on and the motor 4 is operated, the detected voltage becomes lower than the set voltage, and the first voltage comparison circuit 18 outputs a power failure detection signal. Output Sta. When this power failure detection signal 81B is given to the arithmetic circuit 22, the arithmetic circuit 22 immediately stops outputting the drive signal 522a, and the electromagnetic contactor 5 is released accordingly.

When the electromagnetic contactor 5 is released, its auxiliary switch 5a is turned off, so the input circuit 21 receives the closed circuit state signal Ss.
As a result, the arithmetic circuit 22 causes the memory circuit 23 to store the open state (that the electromagnetic contactor 5 is in the open state). Further, the power outage detection signal 8
18 is also applied to the timer circuit 20, so that the timer circuit 20 performs a timing operation only while the power failure detection signal S18 is applied, and outputs a measured time signal S20 indicating the content of the measured time. Thereafter, when the power is restored, the first voltage comparison circuit 18 stops outputting the power failure detection signal Sta, and the timer circuit 20 stops timing operation. When the output of the power failure detection signal S18 is stopped, the arithmetic circuit 22 logically determines whether or not there is an instantaneous power outage that requires restarting based on the length of the measured time (power outage time) indicated by the timed time signal S20. When it is determined that there is a power outage, a drive signal S22a is output. However, at this time, since the permission signal S24 is not output from the delay circuit 24, the trigger circuit 25 does not output the output signal S25. On the other hand, when the detected voltage becomes higher than the specified voltage due to power restoration, the second
The voltage comparison circuit 19 outputs the voltage establishment signal S19, and the delay circuit 24 outputs the set delay time rTJ.
The permission signal S24 is output after waiting for the passage of time.

As a result, the trigger circuit 25 is supplied with both the drive signal s22a and the permission signal 324 and outputs the output signal S2, so that the electromagnetic contactor 5 is re-energized and the motor 4 is restarted. It is done.

Note that when the arithmetic circuit 22 determines that the timer circuit 20 has a long clock time (power outage time) and does not restart, the arithmetic circuit 22 does not output the drive signal S22a, and therefore the electromagnetic contactor 5 The auxiliary switch 5a remains off without being turned on again, and the open state (that the electromagnetic contactor 5 is in the released state) is updated and stored in the memory circuit 23.

According to this embodiment, the following effects can be obtained. In other words, in the event of a momentary power outage, the magnetic contactor 5 is turned on again after the detection voltage, that is, the power supply voltage, is established after the power is restored. There is no delay in restarting the power supply even though the power is turned on or the power supply voltage is established, and it is possible to perform the repowering reliably and shorten the recovery time after the power is restored. Furthermore, after the power supply voltage is established, the electromagnetic contactor 5 is turned on again after waiting for the elapse of the delay time rTJ set by the delay circuit 24, so the electric tlli 4 is restarted in the set order. Therefore, there is no problem such as overcurrent tripping of the power transformer due to restarting of many electric motors at the same time, and even in this case, the delay circuit 24 is configured so that the second voltage comparator circuit 19 receives the voltage establishment signal St. ! Since the permission signal 524 is output on the condition that + is being output, there is no need to reset the delay time ITJ in relation to other motors, and adjustment and maintenance work can be reduced. Moreover, even when the electromagnetic contactor 5 is turned on by turning on the start switch 16, the voltage establishment signal St! of the second voltage comparator circuit engineer 9! Since the output is conditional on + output, there will be no startup failure.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can of course be implemented with appropriate modifications within the scope of the gist.

[Effects of the Invention] As explained above, the motor control device of the present invention waits for the power supply voltage to be established after the power is restored after a momentary power outage and then turns on the switch again, so the motor can be reliably restarted. In addition to reducing recovery time,
In addition, since the power supply is restarted when a preset delay time has elapsed after the power supply voltage is established, the motors can be restarted in the set order and there is no need to reset the delay time. This has an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control circuit in one embodiment of the present invention, and FIG. 2 is an overall electrical configuration diagram of the same embodiment. In the drawing, 1 to 3 are main circuit busbars, 4 is a motor, 5 is an electromagnetic contactor (switch), and 6 is a control transformer (voltage detection means).
, 7 and 8 are control buses, 9 is a control circuit, 18 and 19 are first and second voltage comparison circuits, 20 is a timer circuit, 2
2 is an arithmetic circuit, 23 is a memory circuit, 24 is a delay circuit, 27
indicates a drive circuit.

Claims (1)

[Claims] 1. A switch interposed in the main circuit of the motor, a voltage detection means for detecting the power supply voltage of the motor, and a first circuit that outputs a power failure detection signal when the detected voltage of the voltage detection means becomes less than a set value. a second voltage comparison circuit that outputs a voltage establishment signal when the detected voltage exceeds a specified value; a timer circuit that measures the output time of the power failure detection signal; and a timer circuit that measures the output time of the power failure detection signal. an arithmetic circuit that determines whether restarting is necessary based on time and outputs a drive signal when it is determined to be necessary; and a delay that outputs a permission signal after a delay time set by the arithmetic circuit when the voltage establishment signal is given. A control device for an electric motor, comprising: a circuit; and a drive circuit for re-closing the switch when the drive signal is applied and the permission signal is applied.