JPH02280680A - Start controller for wound-rotor induction motor - Google Patents

Abstract

PURPOSE:To obtain an inexpensive controller by performing variable speed control of the motor for a cam type controller with such speed as corresponding to a set time for stepping notch. CONSTITUTION:A motor 11 for a cam type controller comprises a main circuit 8 and a controller 12 for frequency converter, a sequencer 13, a frequency setting section 14, and a schedule timer 15. In the timer 15, notch stepping time(speed) for the cam type controller is scheduled and the notch step time is inputted to the sequencer 13. The motor 11 rotates with speed corresponding to the notch stepping time, thus starting an induction motor.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a starting control device for a wound induction motor.

[Conventional technology]

Figure 2(a) is a circuit diagram of a wound induction motor, Figure 2~)
Figure 2 (C) is the circuit diagram of the motor for the cam type controller.
is the sequence circuit diagram of the cam type controller, Fig. 2 fd)
is a developed view of the notch contact.

In the figure, l is a wound induction motor, 2 is a main circuit breaker, and 3
is a secondary resistor, is a short-circuit contactor for shorting the secondary resistor 3, 5 is a current transformer CT for measuring the load current, and 6 is tf
When starting the induction motor 1, the cam type controller shown in Fig. 2 (mountains) to (d)
The secondary resistance value is decreased by sequentially short-circuiting with the short-circuit contact 4. In Fig. 2), reference numeral 11 is the electric motor for the cam type controller, and reference numeral 16 is the normal rotation contactor 1.
9 is a free point contactor, 7 is a no fuse breaker, 10
indicates a thermal relay.

This electric motor 11 has a forward rotation contactor 16 and a reverse rotation contactor 9.
It rotates when closed. The normal rotation contactor 16 is closed when the normal rotation contactor excitation coil 16C shown in FIG. 2(C) is energized. When the main circuit breaker 2 is turned on, the forward rotation contactor 16 connects the main circuit breaker auxiliary contact 2A to the current relay 6.
Normally closed contact 6B - notch notch contact C4 in Figure 2 1dl
- The circuit consisting of the auxiliary contact (normally closed contact) 9B of the reverse contactor 9 is closed and energized, thereby causing the motor 11 to rotate forward. The motor 11 continues to rotate in the positive direction until the primary current reaches the set current value of the current relay 6, the current relay 6 is activated, and the normally closed contact 6B opens, and stops when the notch contact C4 opens. do. At this time, the entire resistance of the secondary resistor 3 becomes short-circuited, and the starting of the induction motor 1 is completed. The notch drum 17, the notch contacts C6 and C7, the auxiliary contact (normally closed contact) 16A of the forward rotation contactor 16, and the auxiliary contact (normally closed contact) 9A of the reverse rotation contactor 9 constitute an automatic forwarding circuit.

When the main circuit breaker 2 is opened during operation of the induction motor 1, the main circuit breaker auxiliary contact 2B is closed, and the auxiliary contact 2B - notch contact C3 - auxiliary contact (normally closed contact) 1 of the forward contactor 16
Since the excitation coil 9C of the reversing contactor is energized through 6B, the reversing contactor 9 is closed, the electric motor 11 begins to reverse, and the short-circuited contactors 4, which had been closed, are sequentially opened.

Figure 3 (fat and middle) shows another example in which an electromagnetic contactor is used in place of the short-circuit contactor 4, and its operation timing is set by a timer and made variable. 19 is an auxiliary relay. 19A is an auxiliary relay. Normally closed contacts, 20a, 20b・
-20n is a timer, 21a, 21b...21n is an electromagnetic contactor, 21ac, 21bc,...2 I
nc is the excitation coil of the electromagnetic contactor 21a, 21b = 21n, 20ab, 20bb, ... 20nb is the instantaneous contact of the timer 20a, 20b = 20n, 20ac, 2
0bc, 20nc is tie 720a, 20b...2
0n time-limited contact, 21aa, 21ha, ...2
1na is an auxiliary contact of the electromagnetic contactors 21a, 21b...21n.

This second conventional starting control device is used, for example, when a single long-distance conveyor 100 is driven by a plurality of drive motors M1, .about.M, as shown in FIG. In such a system, a plurality of electric motors M l"'
This is because it is necessary to adjust the resistance short circuit timing when starting M3.

[Problem to be solved by the invention]

The second conventional example has the advantage of being able to adjust the short-circuit timing of each contactor of the secondary resistor, but the current capacity of the electromagnetic contactor is a maximum of several hundred amperes in the 600 volt class, and when the voltage exceeds this However, because the short-circuit contactor is expensive and large, it is not suitable for large-sized, large-capacity induction motors. On the other hand, in the first conventional example, one for large-scale, large-capacity induction motors is prepared, but there is a problem that the short-circuit contactor 4 closes one after another at fixed time intervals, making it impossible to adjust the short-circuit timing.

This invention was made to solve the above problem.
It is an object of the present invention to provide a starting control device for a wound induction motor that can freely adjust the opening and closing timing of a short-circuit contact and can also be used for a large-sized, large-capacity induction motor.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a frequency converter that converts the input frequency of an electric motor for a controller, and a schedule timer device that converts a preset notch advance time into a corresponding frequency according to a set schedule. This configuration includes a sequencer that provides frequency commands.

[Effect]

In this invention, the electric motor of the cam controller is controlled at a variable speed according to the set notch advance time, so by changing the set notch advance time, the closing interval of the short-circuit contact can be freely adjusted.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 8 is a main circuit (inverter) of the frequency converter, 12 is a control device for the frequency converter, 13 is a sequencer, 14 is a frequency setting section, and 15 is a schedule timer.

The schedule timer device 15 has a schedule set for the notch advance time Tn (speed) of each notch of the cam type controller, and inputs the set schedule to the sequencer 13. The sequencer 13 sets a frequency fn* corresponding to the notch advance time Tn according to the set schedule, and uses this as a frequency command fn* to be sent to the inverter control device 12.
Send to.

When the circuit breaker auxiliary contact 2A is closed due to the closing of the main circuit breaker 2, the sequencer 13 uses the contact output as an operation start command and starts sending out the frequency command fn+, and the inverter 8 changes the frequency value of the frequency command fn*. The three-phase alternating current having the following power is started to be supplied to the primary side of the electric motor 11. As a result, the electric motor 11 rotates at a speed corresponding to the notch advance time Tn, the short-circuit contactor 4 is closed, and the induction motor 1 is started. The sequencer 12 is the normally closed contact 6 of the current relay 6.
When B is open, normally closed contact 10B of thermal relay 10
When the normally closed contact 9B of the reversing contactor 9 is closed, the operation is stopped.

When the main circuit breaker 2 is opened, the excitation coil 9C of the reversing contactor 9 is energized, and the electric motor 11 is supplied with power through the reversing contactor 9, on the condition that the contact 12A, which is closed due to the stoppage of the inverter control device 12, is closed. , the electric motor 11 is operated at a constant speed.

In this way, in this example, since the electric motor 11 is configured to be controlled at variable speed, the notch advance time of the cam controller can be freely adjusted by simply rewriting the settings of the timer schedule 15.

Note that it goes without saying that a configuration may be adopted in which variable speed control is performed even when the electric motor 11 is operated in reverse. Further, although the schedule timer 15 has its settings written in by an operator, it may be connected to another device so that the settings can be automatically rewritten.

〔Effect of the invention〕

As explained above, this invention controls the motor of the cam type controller at variable speed, so that starting control of a high-voltage, large-current induction motor that requires adjustment of the starting time can be performed using less expensive equipment than in the past. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
figure! al is a circuit diagram showing the secondary resistance circuit of the induction motor, Figure 2) to (d) are circuit diagrams showing the main parts of the cam type controller, and Figure 3 (a) is the other secondary resistance circuit of the induction motor. FIG. 3('b) is a circuit diagram showing a timer type controller, and FIG. 4 is a schematic diagram of a conveyor driven by a plurality of induction motors. In the figure, 1--wound induction motor, 2--=main circuit breaker, 3--secondary resistor, 4--short circuit contactor, 6--
・-Current relay, 8...Main circuit of frequency converter, 9
--Reverse contactor, 10- Remal relay, 11
- Controller electric motor, 12- Frequency converter control device, 13- Sequencer, 14- Frequency setting unit, 1
5...-Schedule timer. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Figure 2 (Leaning 1)

Claims (1)

[Claims] In a starting control device for an induction motor that sequentially opens and closes short-circuit contacts of a secondary resistor by switching notches using a cam-type controller that is rotated forward and backward by an electric motor, a frequency conversion device that converts the input frequency of the controller electric motor; A starting control device for a wound induction motor, comprising a sequencer that converts a notch advance time preset by a schedule timer device into a corresponding frequency according to a set schedule and provides the frequency command to the frequency conversion device.