CN2456367Y

CN2456367Y - Device for igniting plural motors with one autoformer

Info

Publication number: CN2456367Y
Application number: CN 00261494
Authority: CN
Inventors: 任周林
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-12-29
Filing date: 2000-12-29
Publication date: 2001-10-24
Anticipated expiration: 2010-12-29

Abstract

The utility model relates to a device for starting plural motors with one autoformer, which is provided with a motor startup circuit. The utility model is characterized in that relays are increased on the front of a contactor of an autoformer for starting a plurality of motors in turn, an autotransformer is jointly used by the plurality of motors, and the number of the relays is equal to the number of controlled motors. The motors can be controlled by a single-chip microcomputer or a programmable controller and are orderly started according to the size of motor power from big to small, the startup and control of more than three motors can be realized, and the purposes of material saving and convenient maintenance can be achieved.

Description

The device of an auto-transformer starting multiple motors

The utility model relates to a kind of motor starting protective device.

As everyone knows, three-phase squirrel-cage induction motor is to use the most general electrical equipment in the industrial and agricultural production, thereby it can be converted into electric energy mechanical energy drive mechanical work.The starting current of asynchronous motor than the high 4-5 of its rated current doubly.Starting time is very of short duration, and along with the acceleration of rotor, starting current can gradually reduce unlikely damage motor.But very big starting current can make the impedance drop of transmission line and transformer increase, and causes that line voltage significantly descends, and can influence the operate as normal of other electric equipment on same circuit.For example make the light deepening, even just make at operating other motor because of the torque slack-off even stall of rotating speed that diminishes.For the fluctuation with supply voltage is limited in certain scope, will the starting current of asynchronous motor be limited.Therefore the motor of larger capacity does not allow across-the-line starting.For a long time, adopt the start mode of multiple step-downs such as star triangle, autotransformer decompression, series resistance, current limliting both at home and abroad always.And in the various start modes during owing to the autotransformer decompression starting voltage and starting torque adjustable use the most extensive.

In the starting equipment of motor, common mode is the starter box (cabinet) of an autotransformer of every motor configurations.The occasion of relatively concentrating at load needs repeatedly starting, not only protective circuit cost height, and the complexity that seems.When particularly the multiple motors power difference is big, will causes and to start if elder generation's startup small power motor then starts high power motor.

The utility model purpose is to utilize the start-up control of an autotransformer realization to multiple motors, and startup changes normal running protection program over to after finishing automatically.Saving the metal material (copper conductor and silicon steel sheet) that a plurality of auto-transformer posts consume, and can compress the installing space area, save the cabinet material, safeguard also very convenient.

The utility model project organization is: the device that utilizes an auto-transformer starting multiple motors, have motor start-up circuit, its key is to increase the relay that can start successively multiple motors before the autotransformer contactor in motor start-up circuit.

The shared autotransformer of multiple motors, and number of relays equates with institute control motor quantity.

For the startup of two above motor, start successively by single-chip microcomputer or programmable controller controls and so that the motor power (output) size is descending.

The utility model advantage is that multiple motors starts according to this by watt level, starts safely and efficiently, saves raw material simultaneously, helps reducing cost.

Description of drawings:

Fig. 1 is the theory diagram when in the utility model two motors being adopted relay control.

Fig. 2 is the schematic diagram when in the utility model two above motor being adopted system controlled by computer.

Fig. 3 is a system hardware pie graph when in the utility model two above motor being adopted system controlled by computer.

Fig. 4 is a control program logical flow chart when in the utility model two above motor being adopted system controlled by computer.

Fig. 5 is a system hardware configuration block diagram when in the utility model two above motor being adopted system controlled by computer.Wherein:

1-circuit breaker 2-contactor main circuit

3-current transformer circuit 4-current signal sampling circuit

5-phase failure signal sampling circuit 6-control transformer

7-control mode input circuit 8-voltage sample circuit

9-working power and signaling conversion circuit 10-auxiliary relay control circuit

11-distant place control input contact 12-program control input contact

13-program control output contact 14-Single Chip Microcomputer (SCM) system and peripheral circuit

15-current tuning circuit 16-LED display circuit

17-state relay circuit 18-zero sequence signal sample circuit

The 19-electric-leakage detection circuit

Fig. 6 is a circuit diagram when in the utility model two motors being adopted relay control.

Fig. 7 is the circuit diagram of voltage synchronizing signal sample circuit (8) among Fig. 5.

Fig. 8 is the circuit diagram of current signal sampling circuit among Fig. 5 (4).

Fig. 9 is the zero-sequenceprotection signal circuit (circuit diagram of (18) among Fig. 5.

Embodiment 1:

The control of a compensator starting multiple motors can have multiple implementation, and the one, utilize traditional relay mode to control to two motors; The 2nd, utilize single-chip microcomputer and Programmable Controller to control automatically to two above motor.

Utilize the device of an auto-transformer starting multiple motors, has motor start-up circuit, this start-up circuit is general, as to utilize the circuit of autotransformer decompression, its key be to increase the relay that can start successively multiple motors before the autotransformer contactor in motor start-up circuit.So, the shared autotransformer of multiple motors, and number of relays equates with institute control motor quantity.

For the startup of two motors, adopt two relays to control it and start according to this.

The course of work of circuit is as follows:

1, starting:

2, stop: pressing SB ₁The control circuit outage, control apparatus returns to normal, and motor stops.

When 3, second of starting was the second motor, program was identical with 1, the only different control device that is to use the second motor, and the circuit symmetrical design, operation, maintenance come into plain view.

2: two motor of embodiment are showed as a special case of multiple motors, are easy to realize with the traditional relay control mode.When three above motor are used the relay mode again, just demonstrate and use device many, the circuit complexity, the drawback of poor reliability is so three above motor during with an auto-transformer starting, can consider to use single-chip microcomputer and programmable controller.Start successively so that the motor power (output) size is descending, with convenient.Single-chip microcomputer and peripheral circuit thereof are known technology, and its control circuit is seen Fig. 5.

The startup basic principle of Single-chip Controlling multiple motors is as follows:

This example is an example with present popular MCS-51 series monolithic, is briefly narrated.Major loop still adopts cheap contactor, makes to transmit contactor adhesive whether current path employing relay.The actuating of relay successively realizes Based Intelligent Control by single-chip microcomputer of having programmed and peripheral circuit thereof.

1, each formant is sketched by the circuit working principle:

A, the sampling of voltage synchronizing signal and treatment circuit

The voltage sampling loop is from the secondary direct sample of control loop power transformer, and sampled signal is sinusoidal wave, and the footpath resaistance-capacity coupling circuit is input to comparator.When the positive half cycle of sampled signal arrives, through comparator output high level, directly to single-chip microcomputer, when the sampled signal negative half period arrives, through the comparator output low level; When the voltage sampling signal zero passage, comparator output zero-crossing pulse is directly delivered to singlechip interruption application mouth, in time turn-offs relay circuit and major loop.

B, current signal sampling and treatment circuit:

Current sampling is input to comparator by the current transformer sampling that is connected on any phase of main circuit through resaistance-capacity coupling circuit.When the current sampling signal zero passage, zero-crossing pulse is sent in the comparator upset, outputs to single-chip microcomputer.Its principle is similar to the voltage sampling loop.Current transformer offers the real-time working electric current of motor; behind rectifying and wave-filtering; compare with direct current biasing given on the potentiometer, be input to comparator then, when the overcurrent signal surpasses given direct current biasing; promptly be equivalent to surpass three times of rated current or by the user when the definite value; comparator can be exported interrupt request singal, is transported to the interruption application mouth of single-chip microcomputer, and this moment, single-chip microcomputer can send instruction; turn-off relay circuit and turn-off major loop then, with the protection motor.

C, zero-sequenceprotection signal circuit:

The zero-sequenceprotection signal sampling circuit is obtained zero sequence unsymmetrical current signal by zero-sequence transformer; behind voltage stabilizing didoe and resistance, be added on the comparator; when motor because phase shortage; the two-phase short circuit; single-phase shorted to earth; motor winding partial short-circuit or electric leakage etc. are former thereby when producing situation such as unsymmetrical current; the unbalance voltage that produces in the load of zero-sequence transformer can surpass the puncture voltage of voltage stabilizing didoe; comparator upset this moment; send and interrupt the application signal; deliver to the interruption application mouth of single-chip microcomputer; single-chip microcomputer sends and turn-offs instruction; turn-off relay circuit earlier; be equal to the control loop that has turn-offed major loop because relay electric-loss discharges, the major loop outage is with the protection motor.And motor also will produce unsymmetrical current owing to reasons such as manufacturing process, the pressure drop that this electric current produces in the load of zero-sequence transformer is less than the puncture voltage of voltage stabilizing didoe, therefore comparator can not overturn, and just can not send yet and interrupt the application pulse, and motor can normally move.

No matter the utility model is the relay control forms, or single-chip microcomputer Based Intelligent Control form, can play economical with materials, optimize circuit, improve plurality of advantages such as reliability and automatization level, stronger practicality is arranged.Single-chip Controlling has made full use of monitoring, control and the adjustment function of Single Chip Microcomputer (SCM) system.Not only program control is carried out in the starting of motor, and can be carried out control in real time the running of motor.Comprehensive to the motor circuit defencive function.During many power concentration, can be expanded, be easy to the microcomputer network with automation control, be realized remote automation control Single Chip Microcomputer (SCM) system.

No matter relay control forms or Single-chip Controlling form, all should note following some:

1, in the trigger circuit of all motor, interlock all should be set, prevent to start simultaneously.

When 2, two above motor capacities did not wait, suitable first starting capacity was bigger, in the circuit anti-error starting device should be set.

During 3, with a compensator starting multiple motors, autotransformer should be chosen according to the maximum motor of capacity.

4, the working method of autotransformer should be selected the 120S working form.

Claims

1, utilizes the device of an auto-transformer starting multiple motors, have motor start-up circuit, it is characterized in that increasing before the autotransformer contactor in motor start-up circuit the relay that can start successively multiple motors.

2, the device of an auto-transformer starting multiple motors according to claim 1 is characterized in that the shared autotransformer of multiple motors, and number of relays equates with institute control motor quantity.

3, according to the device of claim 1,2 described auto-transformer starting multiple motors, it is characterized in that startup, start successively by single-chip microcomputer or programmable controller controls and so that the motor power (output) size is descending for two above motor.