JPH0526952Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a motor restart circuit that restarts the motor after a predetermined period of time when the power is restored after a temporary power outage while the motor is in operation. Involved in restart circuits for high-voltage motors that perform ground fault interruption, remote operation, etc.

[Prior art and its problems]

When a power supply to a motor is cut off while the motor is in operation and the power is retransmitted, it is convenient to turn on the main contacts of the circuit again and automatically put the motor into operation if the power cut is for a short time. However, in general, a large starting current flows through motors when they are started, so if a plurality of motors are started at the same time, it becomes difficult to start due to a voltage drop in the power supply, and sometimes restarting becomes impossible. For this reason, a motor restart circuit is known in which a group of motors is divided into individual motors or groups, and the motors are started individually at staggered times using a timer.

An example of such a conventional electric motor restart circuit is shown in FIG. In FIG. 2, a motor circuit 1 detects an abnormality outside the main circuit that supplies power to a motor 7 via a power supply 2, a disconnector 3, a main contact 4a of a circuit breaker 4, a current transformer 5, and a zero-phase current transformer 6. The relay for detecting is connected as follows. That is, the power failure detection relay 8, which has a detection b contact 8a and is released when the power supply voltage drops, is connected to the voltage transformer 9 and the fuse 10.
An overcurrent relay 11 with a contacts 11a and 11b that closes due to R-phase and T-phase overcurrent is connected to the power supply 2 via a current transformer 5, and a directional ground fault relay 12 with an a contact 12a connects to a zero-phase current transformer. 6, respectively.

This motor circuit 1 is controlled by an operation circuit 13, an abnormality detection circuit 14, and a time limit circuit 15 connected between a DC control power source PN.

The operating circuit 13 has a main contact 4a and a circuit breaker a contact 4.
b, a circuit breaker 4 having a circuit breaker b contact 4c, a closing coil 4d, and a stopping coil 4e; a starting contact 16;
a, a stop contact 16b, and an interlocking b contact 16c,
An operation switch 16 is provided in which a stop contact 16b and a b contact 16c are interlocked, and a closing coil 4d is a starting contact 1.
A circuit is formed in which the stop coil 4e is connected in series with the stop contact 16b, and the starting contact 18a and the stop contact are connected via a cable 17 to operate the operating circuit 13 from a distance. 18b is connected to a remote operating switch 18 having a b contact 18c that interlocks with this contact 18b, the starting contact 18a of this operating switch 18 is connected to the starting contact 16a, and the stopping contact 18b is connected to the stopping contact 16.
b are connected in parallel with each other. 19a, 2
0a and 21a are both the A contacts of each auxiliary relay of the abnormality detection circuit 14 described below, when an abnormality such as a low voltage including a power outage (hereinafter, low voltage is included in a power outage), an overcurrent, or a ground fault occurs in the motor circuit. It closes, energizes the stop coil 4e, and opens the main contact 4a. Note that a so-called interlock circuit is inserted in which a b contact of an overcurrent relay or a ground fault relay is connected in series with the closing coil 4d, and the closing coil 4d cannot be energized when this relay is activated, but this circuit is omitted here.

The abnormality detection circuit 14 includes a detection auxiliary relay 1 having a detection auxiliary a contact 19a and a detection auxiliary b contact 19b.
9. A series circuit between the b contact 8a of the power failure detection relay 8 and the auxiliary relay 19, including an overcurrent auxiliary relay 20 having an a contact 20a and a b contact 20b, and a ground fault auxiliary relay 21 having an a contact 21a and a b contact 21b. , R-phase a contact 11a of overcurrent relay 11 and T
It is formed of a circuit in which the phase a contacts 11b are connected in parallel to each other and connected in series with the auxiliary relay 20, and a series circuit of the a contact 12a of the directional ground fault relay 12 and the auxiliary relay 21.

The timer circuit 15 has two a contacts 22a and 22b.
A power-on memory relay 22 having an A contact 23a, a power failure memory relay 23 having an A contact 23a, a timer 24 having a reinsertion contact 24a, and a reset switch 25 having B contacts 25a and 25b, with the A contact 4b and the A contact 22a connected in parallel. Connected circuit, b contact 25
a, a circuit in which all the closing memory relays 22 are connected in series, an a contact 22b, a b contact 16c, a b contact 18
c, b contact 20b, b contact 21b, b contact 4c,
A circuit in which the B contact 25b and the power failure memory relay 23 are all connected in series, the A contact 23a, the B contact 19b,
It is formed from a circuit in which all the timers 24 are connected in series, and the connection point between the b contact 4c and the b contact 25b, and the a
The connection point between the contact 23a and the b contact 19b is bridged.

To start the motor 7 at all times, after turning on the disconnector 3, close the starting contact 16a of the operation switch 16, the turning coil 4d is energized, the circuit breaker 4 is turned on, the main contact 4a is closed, and the motor 7 is started. , can drive normally. Further, to stop the electric motor 7, if the stop contact 16b is closed, the stop coil 4e is energized and the main contact 4a is opened. At this time, as will be described later, the closing memory relay 22 operates and closes the a contact 22b, but the b contact 16 interlocks with the stop contact 16b.
Since c is open, relay 23 and therefore timer 24
doesn't work. To operate from a distance, the electric motor 7 can be started and stopped in the same manner as described above by operating the operation switch 18. At this time as well, when the stop contact 18b is closed, the b
Since contact 18c is open, relay 23 and therefore timer 24 do not operate.

To describe in detail the state of the restart circuit while the motor 7 is operating, when the circuit breaker 4 is closed, the close contacts 16a and 18a automatically return to their original state, and the contacts of the operating circuit 13 are all opened as shown in FIG. Continue the condition. Also, in the abnormality detection circuit 14, the voltage of the power supply 2 is normal and the power failure detection relay 8 is operating, so the b contact 8a is open, but the other relays 11 and 12 are not operating, so they all remain open. . In the time circuit 15, since the circuit breaker 4 is closed, the a contact 4b is closed and the b contact 4c is open. Accordingly, the closing memory relay 22 operates, and the a contact 22a closes to self-hold. At this time, the a contact 22b is also closed, but the circuit breaker b contact 4c is open, so the power failure memory relay 23 does not operate and the timer 24 does not start.

When the power supply 2 has a power failure, the power failure detection relay 8 is released, the b contact 8a is closed, and the detection auxiliary relay 19 is activated. Then, the a contact 19a closes and stops the coil 4.
Since power is applied to e, the main contact 4a and the a contact 4b open, and the b contact 4c closes. Since the closing memory relay 22 is self-holding and the a contact 22b is closed, b
When the contact 4c closes, the power failure memory relay 23 operates, closing the a contact 23a. However, since the detection auxiliary relay 19 operates and opens the b contact 19b, the timer 24 does not start. When the power supply 2 is restored here, the power failure detection relay 8 operates, and the auxiliary relay 1
9 is released and the b contact 19 closes, so the timer 24
starts. After a predetermined period of time has elapsed, the restart contact 24a is closed and the main contact 4a is turned on to restart the electric motor 7. At this time, reset switch 2
5 is opened once, the power-on memory relay 22 and the power failure memory relay 23 are released, and the timer 24 is reset to prepare for the next power failure.

By staggering the set time limits of the respective timers of a plurality of electric motors having such restart circuits, these electric motors can be started in sequence.

Note that the operations of the overcurrent relay 11 and the ground fault relay 12 will be omitted.

By the way, in this time limit circuit, when the electric motor 7 is operating, the closing memory relay 22 is self-holding, and a
The contact 22b is closed, and the power failure detection relay 8 is activated and the b contact 19b is also closed, so when you want to stop the operation of the motor 7 or when there is an overcurrent in the motor circuit 1,
Circuit breaker 4 is activated due to an abnormality other than a power outage such as a ground fault.
If the power failure memory relay 23 is activated to prevent the A contact 23a from opening when the power is cut off, the B contact 4c will close and the timer 24 will start, and after a predetermined time the restart contact 24a will be closed and the circuit will be cut off. Vessel 4
I end up re-inserting it. To prevent this, the power failure memory relay 23 includes the B contacts 16c and 18c of both operation switches 16 and 18, as well as each B contact 20.
b, 21b are all connected in series together with the b contact 4c to prevent the timer 24 from starting when the circuit breaker 4 is cut off other than a power outage. However, for this reason, there are a large number of B contacts that must be closed at all times, and if a contact failure occurs in even one of these B contacts, there is a drawback that the timer 24 will not start even in the event of a power outage. In addition, the b contact 18c of the operation switch 18 installed at a distance is also connected to this power failure memory relay 2.
The disadvantage is that an expensive cable 17 is required for the series connection with 3.

[Purpose of invention]

The present invention aims to eliminate the above-mentioned drawbacks and provide an inexpensive and reliable electric motor restart circuit.

[Key points of the idea]

The present invention opens the main contact 4a when the power supply 2, which is supplied with power through the main contact 4a and is operating the motor 7, temporarily loses power, and when the power is restored, the main contact 4a is turned on again after a predetermined period of time to start the motor. A restart circuit for the electric motor 7; the main contact 4a and the circuit breaker a contact 4.
a circuit breaker 4 having a closing coil 4d and a stopping coil 4e; an operating switch 1 having a starting contact 16a connected in series to the closing coil 4d; and a stopping contact 16a connected in series to the stopping coil 4e.
6, a restart contact 24a is connected in parallel to the start contact 16a, and a detection auxiliary a contact 19a is connected in parallel to the stop contact 16b.
3; A power failure detection relay 8 which has a detection b contact 8a and is released when the voltage of the power source 2 decreases; a power failure detection relay 8 which has the detection auxiliary a contact, another detection auxiliary a contact 19c, and a detection auxiliary b contact 19b; B contact 8a
an abnormality detection circuit 14 including a detection auxiliary relay 19 connected in series; a power failure memory relay 23 having a memory a contact 23a and connected in series with the detection auxiliary contact 19c, the circuit breaker a contact 4b, and the reset switch 25; , has the re-close contact 24a, the memory A contact 23a and the detection auxiliary B contact 1.
9b and a timer 24 connected in series with each other to bridge the connection point between the circuit breaker A contact 4b and the reset switch 25, and the connection point between the memory A contact 23a and the detection auxiliary B contact 19b. the operating circuit 13;
The abnormality detection circuit 14 and the time limit circuit 15 are each operated by the control power supply PN, and when the power supply fails, a detection auxiliary relay operates through the contacts of the circuit breaker and the contacts of the power failure detection relay. In combination, it restarts the motor by distinguishing between an artificial stop command for the motor and a stop command due to an abnormality such as an overcurrent or ground fault other than a power outage in the electric circuit. The aim is to simplify the timer circuit by eliminating the b-contact to assist in detecting abnormalities other than power outages, thereby improving reliability and reducing costs.

[Example of idea]

Embodiments of the present invention will be described in detail below with reference to FIG. In FIG. 1, parts that operate in the same way as in FIG. 2 are given the same reference numerals to avoid duplication of detailed explanation. In FIG. 1, the motor circuit 1 and the operation circuit 13 are completely the same as those of the conventional ones, and the abnormality detection circuit 14 has a detection auxiliary relay 19 with an A contact 19c in addition to the A contact 19a and the B contact 19b.
The only difference is that .

The timer circuit 15 includes a power failure memory relay 23 having a memory a contact 23a, a timer 24 having a reinsertion contact 24a, and a reset switch 25.
9c, A contact 4b, reset switch 25, and power failure memory relay 23 are all connected in series;
A circuit in which the A contact 23a, the B contact 19b, and the timer 24 are all connected in series is connected between the control power supply PN, and the connection point between the A contact 4b and the reset switch 25, and the connection point between the A contact 23a and the B contact 19b. There is a bridge between the two.

To start the motor 7 at all times, as in the circuit shown in Fig. 2, after turning on the disconnector 3, close the starting contact 16a of the operating switch 16, the circuit breaker 4 is turned on, and the main contact 4a is closed, allowing normal operation. . At this time a
Contact 4b closes, but power failure detection relay 8 operates and opens contact b 8a, so detection auxiliary relay 19
does not operate, and since the a contact 19c is open, neither the power failure memory relay 23 nor the timer 24 operates. In addition, to stop, if the stop contact 16b is closed, the main contact 4a opens. At this time, since the a contact 19c is open and the a contact 4b is also open, neither the power failure memory relay 23 nor the timer 24 operates. In other words, in this circuit, the A contact 19c, which closes only in the event of a power outage, is connected in series to the power outage memory relay 23, so the power outage memory relay 23 is activated especially when there is an abnormality such as an artificial interruption other than a power outage or an overcurrent ground fault. There is no need to avoid this, and the circuit is simplified.

Here, when the power supply 2 is out of power, the power outage detection relay 8
is released and the B contact 8a closes, and the detection auxiliary relay 19 operates to close the A contact 19a and the circuit breaker 4
The main contact 4a and the a contact 4b are opened. Further, since the a contact 19c is closed, the power failure memory relay 23 is operated, the a contact 23a is closed, and the fact that the power supply 2 has been interrupted is memorized. However, since the b contact 19b is open, the timer 24 does not start. When the power supply 2 is restored, the power failure detection relay 8 operates to open the b contact 8a, and the detection auxiliary relay 19 is released, so the a contact 19c opens and the b contact 19b closes. At this time, the power failure memory relay 23 is self-holding with the a contact 23a closed, so the timer 24 starts, and after a predetermined time, the re-close contact 24a is closed to operate the circuit breaker 4, and the main contact 4a is closed to start the motor. Restart 7. At this time, the reset switch 25 is once opened to release the power failure memory relay 23 and reset the timer 24 to prepare for the next power failure.

Of course, this restart circuit, like the conventional one, can start the motors in sequence by staggering the set time limits of the respective timers of a plurality of motors having such a restart circuit.

Note that the operations of the overcurrent relay 11 and the ground fault relay 12 will be omitted.

[Effect of idea]

As described above, according to the present invention, the A contact of the detection auxiliary relay, which is activated by releasing the power failure detection relay, closes only in the event of a power outage, and the power failure memory relay is activated, closing the memory A contact, and the power is interrupted. When the power is restored, the B contact of the detection auxiliary relay is closed, a timer is started, and the motor is restarted after a predetermined period of time. In order to prevent the power failure memory relay from operating especially in the event of an abnormality such as a power failure, there is no need to insert a b contact that opens in an abnormality other than a power failure. This simplifies the time circuit and improves reliability. Further, since the interlocking b-contact switch for remote operation is omitted, the number of core wires in the cable may be small.Furthermore, since the closing memory relay is omitted, it is inexpensive and excellent, and is particularly suitable for high voltage applications.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing an embodiment of a motor restart circuit according to the present invention, and FIG. 2 is a wiring diagram showing a conventional example of a motor restart circuit. 2...Power source, 4...Circuit breaker, 4a...Main contact of the breaker, 4b...A contact of the breaker, 4d...
Closing coil, 4e...stopping coil, 7...motor, 8...power failure detection relay, 8a...detection b contact, 13...operation circuit, 14...abnormality detection circuit,
15...Time limit circuit, 16...Operation switch, 16
a, 18a... Start contact, 16b, 18b... Stop contact, 19... Detection auxiliary relay, 19a, 19
c...Detection auxiliary a contact, 19b...detection auxiliary b contact, 23...power failure memory relay, 23a...memory a
Contact, 24...Timer, 24a...Re-close contact,
25...Reset switch.

Claims (1)

[Scope of Claim for Utility Model Registration] An electric motor that is supplied with power through a main contact and opens the main contact when there is a temporary power outage while the motor is operating, and when the power is restored, the main contact is turned on again after a predetermined period of time to start the motor. The operation circuit 13 and the abnormality detection circuit 14 are respectively connected to the control power supply.
and a timer circuit 15, the operation circuit 13 includes the main contact 4a, the circuit breaker a contact 4b, the closing coil 4d, and the stopping coil 4.
e, and an operating switch 16 having a starting contact 16a connected in series to the closing coil 4d and a stopping contact 16b connected in series to the stopping coil 4e, and a restart switch connected in parallel to the starting contact 16a. A contact 24a is connected, and a first detection auxiliary a contact 19a is connected in parallel to the stop contact 16b, and the abnormality detection circuit 14 has a detection b contact 8a, which is released when the voltage of the power supply decreases. power failure detection relay 8 and the first detection auxiliary a contact 19
a, a detection auxiliary relay 19 having a second detection auxiliary a contact 19c and a detection auxiliary b contact 19b and connected in series with the detection b contact 8a; the time limit circuit 15 has a memory a contact 23a; The second detection auxiliary a contact 19c and the circuit breaker a
A power failure memory relay 23 connected in series with the contact 4b and the reset switch 25, and a timer having the restart contact 24a and connected in series with the memory A contact 23a and the detection auxiliary B contact 19b, A restart circuit for a motor, characterized in that a connection point between a circuit breaker a contact 4b and a reset switch 25 and a connection point between the memory a contact 23a and the detection auxiliary b contact 19b are bridged.