JPH06189587A - Motor controller - Google Patents

Abstract

PURPOSE:To prevent the damage and mistrip of apparatuses caused by the starting current of a motor. CONSTITUTION:Malfunction is detected by comparing a main-circuit current signal detected by a current transformer 5, in a logic operation circuit 14, with a malfunction judging reference value settable to an arbitrary value within a range, and a command to open an electromagnetic contactor 4 is outputted at the time of malfunction. A memory circuit 17 samples starting characteristics of a motor 2, and stores starting currents. Besides, the operation characteristic of a wiring circuit-breaker 3 and the endurance characteristic of the electromagnetic contactor 4 are set beforehand in a characteristic setting circuit 18. And a logic operation circuit 14 outputs an alarm signal with the help of an alarm circuit 20 when a sampled value of a starting characteristic of the motor 2 exceeds its set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor control device for controlling opening and closing of an electric motor by using a switch such as an electromagnetic contactor and protecting the electric motor. The present invention relates to an electric motor control device that prevents damage to a vehicle and a miss lip.

[0002]

2. Description of the Related Art Recently, some unit devices of a control center house a motor control device having many functions such as operation / stop control, protection and monitoring of an induction motor by applying a microcomputer. Have been served.

The protection function of this type of motor control device constantly monitors the main circuit current of the motor with a reference value for abnormality determination, and when an abnormality such as overload, open phase or ground fault is detected, the main circuit is activated. By opening the connected electromagnetic contactor, the electric motor is protected and the cause of the abnormality is displayed outside. The reference value for abnormality determination can be arbitrarily set within a certain range, and for example, for a load with a long start-up time, a normal protection function can be performed by setting a reference value according to its start-up characteristic. It is configured.

[0004]

By the way, in such a motor control device, the reference value for abnormality determination is set by
At the installation site, the starting current, starting time, and normal current of the electric motor are actually measured, the reference value is determined from the measured values, and this is set.

However, in this case, if the set time is too long, there are problems such as exceeding the withstand capability of the electromagnetic contactor, entering the operation area of the circuit breaker for wiring, and causing a mistrip. SUMMARY OF THE INVENTION An object of the present invention is to provide an electric motor control device that can prevent damage to equipment and miss strips due to electric motor starting current.

[0006]

SUMMARY OF THE INVENTION A motor controller according to the present invention includes a circuit breaker for disconnecting a main circuit between a power bus and an electric motor, an electromagnetic contactor for opening and closing the main circuit, and a main circuit current. A current converter for detecting a current, an input circuit for inputting start and stop operation signals for opening and closing the electromagnetic contactor, and an abnormality in which a detection signal from the current converter can be set to an arbitrary value within a certain range. A motor control device having a logical operation circuit that determines whether or not there is an abnormality by comparing with a determination reference value and outputs an opening command for the electromagnetic contactor when there is an abnormality, and a memory circuit that samples the starting characteristic of the electric motor and stores a starting current. In a characteristic setting circuit in which at least the operating characteristics of the circuit breaker for wiring and the withstand capacity characteristics of the electromagnetic contactor are preset, and when the sampling value exceeds the setting value. Characterized in that a warning circuit for outputting a broadcast signal.

[0007]

In the first operation such as the trial operation of the electric motor, the current value is automatically measured at regular time intervals after the start of operation, and the current and time at this time are stored. If this value exceeds the characteristics of the circuit breaker for wiring and the withstand capability of the electromagnetic contactor set in advance in the setting circuit, an alarm signal is output from the alarm circuit. It becomes possible to prevent damage to vessels and the like.

[0008]

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 the drawings. That is, FIG. 1 shows a circuit configuration for one unit of the control center. In the figure, 1 is a three-phase main circuit that supplies power to an induction motor 2 that is a load. The main circuit 1 includes a circuit breaker 3 for wiring, an electromagnetic contactor 4, and a main circuit current for detecting current. A current converter 5 and a zero-phase current transformer 6 that detects a zero-phase current of the main circuit are provided as main circuit devices. The primary winding 7a of the operating transformer 7 is connected between the two phases of the main circuit 1 between the load side of the wiring breaker 3 and the power source side of the electromagnetic contactor 4. The output voltage of the secondary winding 7b of the operating transformer 7 is applied to the bus bar 8 as a power source for the operating circuit. The coil 4a of the electromagnetic contactor 4 having one end connected to the bus bar 8 so as to use it as one power supply line, the auxiliary contact 4b, the start operation switch 9, and the other end of the stop operation switch 10 have the control circuit 11 Operation signal output terminal 11
a and the operation signal input terminal 11b.
As a result, the control circuit 11 receives the start signal from the start operation switch 9 and the stop signal from the stop operation switch 10 to turn on and off the coil 4a, thereby opening and closing the electromagnetic contactor 4 and the current converter 5 as well. , Has a function of inputting a current signal from the zero-phase current transformer 6 and performing protection operations such as overload protection, open-phase protection, and ground fault protection of the induction motor 2. The power of the control circuit 11 is supplied from the tertiary winding 7c which is insulated from the secondary side of the operation transformer 7 in order to prevent intrusion of switching noise generated by the coil 4a of the electromagnetic contactor 4. ing.

Further, the control circuit 11 inputs a detection current according to the magnitude of the main circuit current output from the current converter 5 and the zero-phase current transformer 6, and a current detection circuit 12 from this current detection circuit 12. A drive circuit 13 that operates the electromagnetic contactor 4 while calculating the detection signal to monitor the abnormality of the main circuit current
It is composed of a logical operation circuit 14 for outputting a command, a display circuit 15 for displaying the main circuit current value and the cause of abnormality of the main circuit 1, and an external output circuit 16 for outputting the content of the abnormality to the outside. The control circuit 11 is further provided with a memory circuit 17 corresponding to the object of the present invention. The memory circuit 17 has a current value i (i1 ... In) sampled at a constant interval tS from the start of activation shown in FIG. And its time t (t1 ... tn)
Is memorized.

In the characteristic setting circuit 18, the operating characteristics of the wiring breaker shown in FIG. 2 and the withstand capability of the electromagnetic contactor are set. Data for all the circuit breakers and electromagnetic contactors used in the control center are set therein, and the characteristic setting switch 19 selects the characteristic of the corresponding circuit breaker and the withstand capacity of the electromagnetic contactor.

As shown in FIG. 2, the sampled starting current value i and its time t in the above structure exceed the i2 point of the characteristic curve IMCCB for the circuit breaker and the iX point of the withstand curve IMC for the electromagnetic contactor, for example. In this case, since the logical operation circuit 14 outputs an alarm signal via the alarm circuit 20 and the display circuit 15 displays an abnormality,
It can prevent miss-strips and damage to instruments.

[0012]

According to the electric motor control device of the present invention, the starting characteristic of the electric motor is obtained by the operation of the electric motor, and the alarm signal is output when the operating characteristics of the circuit breaker for wiring and the withstand capacity of the electromagnetic contactor are exceeded. Therefore, excellent effects such as prevention of mistrip and damage to equipment can be expected.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a motor control device according to the present invention.

FIG. 2 is a diagram showing a motor current characteristic and a current characteristic which is a protection condition.

[Explanation of symbols]

1 is a main circuit, 4 is an electromagnetic contactor, 5 is a current converter, 6 is a zero-phase current transformer, 11 is a control circuit, 12 is a current detection circuit, 14
Is a logical operation circuit, 17 is a memory circuit, 18 is a characteristic setting circuit, 19 is a characteristic setting switch, and 20 is an alarm circuit.

Claims (1)

[Claims] 1. A circuit breaker for breaking a main circuit between a power bus and an electric motor, an electromagnetic contactor for opening and closing the main circuit, a current converter for detecting a main circuit current, and the electromagnetic contactor. The presence or absence of an abnormality is determined by comparing the input circuit that inputs the start and stop operation signals for opening and closing the switch and the abnormality determination reference value that can set the detection signal from the current converter to an arbitrary value within a certain range. In a motor controller having a logical operation circuit that outputs a command to open an electromagnetic contactor when an abnormality occurs, and a memory circuit that stores the starting current by sampling the starting characteristics of the electric motor, at least the operating characteristics of the circuit breaker for wiring and A characteristic setting circuit in which a withstanding characteristic of the electromagnetic contactor is preset, and an alarm circuit for outputting an alarm signal when the sampling value exceeds a set value are provided. Electric motor control device.