JP3042930B2 - Load control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device having an electromagnetic contactor and a main circuit current detector in a main circuit for controlling and protecting the operation of a load.

[0002]

2. Description of the Related Art As an example of this type of load control device, a control center having a function of controlling and protecting loads such as an electric motor is known. That is, in the control center, a plurality of units in which main circuit devices such as a circuit breaker, an electromagnetic contactor, and a current converter are grouped for each unit circuit are housed in multiple stages, and a start / stop display lamp, It is configured by providing a display panel provided with a start operation switch, a stop operation switch, and the like.
In recent years, in order to be able to easily cope with a change in the specifications of the unit, a configuration in which necessary functions among a plurality of control and protection functions can be appropriately set, added, and changed by adopting electronic applied technology. It has become. FIG. 3 shows an example.

That is, FIG. 3 shows one of the control centers.
1 schematically shows a circuit configuration of a unit, in which a main circuit 3 between a three-phase power bus 1 and a motor 2 serving as a load includes a circuit breaker 4 and a current converter 6 for detecting main circuit current, respectively. And a zero-phase current transformer 7 for detecting a ground fault current. On the load side of the circuit breaker 4, control buses 9 a and 9 b are connected to the secondary side of the operation transformer 8.

The control unit 10 supplied with power from the control buses 9a and 9b via a DC power supply circuit (not shown) is mainly composed of a logical operation circuit 11 composed of a microcomputer. The logic operation circuit 11 receives, via an input circuit 14, ON signals from a start operation switch 12, a stop operation switch 13, and a normally open auxiliary contact 5a of the electromagnetic contactor 5, which are operation devices. In addition, each signal from the current converter 6 and the zero-phase current transformer 7 is received via the A / D conversion circuit 15, and the operation coil 5b of the electromagnetic contactor 5 is controlled to be turned on / off via the output circuit 16. It has become. The storage circuit 17 stores control programs and function data for executing control operations such as protection operations such as overload, open phase, undercurrent, and ground fault, and instantaneous power failure start and timed restart. The arithmetic circuit 11 executes a protection operation and a control operation based on the control program, the function data, and the input signal. The setting circuit 18
It is composed of a number of selection switches (not shown) so that the function data stored in the storage circuit 17 can be set and selected as desired at the installation site of the control center.

Since each device of the main circuit 3 is controlled by the logical operation circuit 11 based on the control program, for example, even if the specification of the unit is changed, the control program is changed. By doing so, it can be easily dealt with.

[0006]

However, in such a control center, when the chattering phenomenon of the electromagnetic contactor 5 occurs, problems such as contact welding and contact falling off occur. Electromagnetic contactor 5
In addition to the failure, the entire unit may fall into a function stop state. Therefore, in order to prevent such a function stop state beforehand and to improve the reliability of the control center, the cause of the chattering phenomenon of the electromagnetic contactor is detected in advance, and the chattering is applied to the electromagnetic contactor 5. It is necessary to prevent this from occurring, but this has been an unsolved problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to monitor operation commands such as operation, stop signal, and upper relay, which are factors of the electromagnetic contactor so that chattering does not occur. , To block the chattering occurrence signal.

[0008]

In order to achieve the above object, the present invention has a detecting means for detecting a state of an operation signal, and a judgment circuit for judging a time of the operation signal. The signal time at which chattering of the electromagnetic contactor occurs is set in advance. This set value is compared with the on / off timing of the detected input signal, and when this value is a timing shorter than the set time of the determination circuit,
It is characterized in that a closing signal of the electromagnetic contactor is blocked and an abnormal state of the signal is displayed on a display unit.

[0009]

According to the load control device of the present invention, the electromagnetic contactor detects an operation command such as a run / stop signal and a higher-level relay which causes chattering, and an electromagnetic contactor set in advance generates chattering. Judgment of the signal timing, if normal, output the closing command to the electromagnetic contactor from the output unit, and if abnormal, block the output and display it on the display unit to prevent chattering of the electromagnetic contactor beforehand The reliability of the load control device can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a control center will be described below with reference to FIG.

FIG. 1 shows an electrical configuration of a unit constituting a control center. In FIG. 1, a main circuit 2 is provided between a three-phase power supply bus 21 and a motor 22 as a load.
The main circuit 23 includes a circuit breaker 24, an electromagnetic contactor 25, a current converter 26 for detecting a main circuit current, and a zero-phase current transformer 27 for detecting a ground fault current in this order from the power supply side. Is provided. In the main circuit 23, a primary side of an operation transformer 28 is connected to a load side of the wiring breaker 24, and a control bus 29a,
29b is connected.

The control unit 30, which is supplied with power from the control buses 29a and 29b through a DC power supply circuit (not shown), is constituted mainly by a logic operation circuit 31 as a logic operation means constituted by a microcomputer. This logical operation circuit 3
Reference numeral 1 denotes a start operation switch 32, a stop operation switch 33, and an ON signal from a normally open auxiliary contact 25a included in the electromagnetic contactor 25 via an input circuit 34, respectively. 26 and the zero-phase current transformer 27 are respectively received via an A / D conversion circuit 35, and the operating coil 25b of the electromagnetic contactor 25 is connected to an output circuit 3
6, and the power cutoff control is performed. The storage circuit 37 stores control programs and function data for executing protection operations such as overload, open phase, insufficient current, and ground fault, and control operations such as instantaneous power failure restart and timed restart. The logical operation circuit 31 executes a protection operation and a control operation based on the control program, the function data, and the input signal. The setting circuit 38 includes a number of selection switches (not shown) so that the function data stored in the storage circuit 37 can be set and selected as desired at the installation site of the control center.

The detection circuit 40, which is a detection means, is supplied with the operation signal 32 and the stop signal 33 from the input circuit 34, and detects the input state shown in FIG. The determination circuit 41 determines whether or not the input signal detected by the detection circuit 40 repeats the on / off signal within a set time T. FIG. 2A shows a case where the input signal is a one-shot signal within the set time T or a continuous signal longer than the set time T. In this case, the input signal is determined as a normal input signal, and the logical operation circuit 31 performs the logical operation. Then, the operation coil 25b of the electromagnetic contactor 25 is turned on from the output unit 36. FIG.
(B) is a case where the input signal repeatedly turns on and off within the set time T. In this case, the detection circuit 40 detects the on / off repetition signal, and the determination circuit 41 determines that the signal is an abnormal signal and performs a logical operation. The circuit 31 makes a logical decision to block the output to the output unit 36 and display it on the display unit 42. As a result, since the operating coil 25b of the electromagnetic contactor 25 is not turned on, chattering of the electromagnetic contactor 25 can be prevented.

[0014]

According to the present invention, as apparent from the above description, the cause of chattering of the electromagnetic contactor is detected in advance, and the output to the operating coil of the electromagnetic contactor is blocked and displayed. Thus, the reliability of the entire load control device can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic electric circuit configuration diagram showing an embodiment of a load control device according to the present invention.

FIG. 2 is a signal time chart shown for explaining the operation;

FIG. 3 is a diagram corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

21 is a power supply bus, 22 is a motor, 23 is a main circuit, 24 is a circuit breaker, 25 is an electromagnetic contactor, 25b is an operating coil, 26 is a current converter, 27 is a zero-phase current transformer, and 31 is a logical operation. Circuit, 37 is a storage circuit, 38 is a setting circuit, 41 is a determination circuit, and 42 is a display unit.

Continuation of front page (56) References JP-A-56-149722 (JP, A) JP-A-51-76961 (JP, A) JP-A-47-44054 (JP, A) JP-A-5-74259 (JP, A) JP-A-59-83594 (JP, A) JP-A-58-171546 (JP, U) JP-A-63-105031 (JP, U) JP-A-3-100342 (JP, U) JP-A 63-67877 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 33/59 H01H 47/00 H01H 9/54

Claims (1)

(57) [Claims] 1. A main circuit comprising an electromagnetic contactor and a current converter interposed between a power supply bus and a load, wherein said main circuit includes a current converter. In an apparatus for performing operation control and protection, a detection means for detecting the on / off timing of the load operation / stop command is compared with a predetermined set time and the on / off timing, and the on / off timing is determined. When the off-timing is repeatedly turned on and off within the set time, it is determined that the signal is an abnormal signal, and a judgment circuit that blocks an input command to the electromagnetic contactor and outputs the signal to a display unit is provided. Load control device.