CN2232159Y

CN2232159Y - Self-adaptation A.C. contactor

Info

Publication number: CN2232159Y
Application number: CN 95202164
Authority: CN
Inventors: 李欣
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-01-23
Filing date: 1995-01-23
Publication date: 1996-07-31
Anticipated expiration: 2005-01-23

Abstract

The utility model provides a self-adaptation AC contactor, which is the improvement of existing AC contactors. The utility model is additionally provided with three pairs of auxiliary contacts; one of polar plates of main contact is connected with one static contact, and the other polar plate is connected with the other static contact by a normally closed contact. The auxiliary contacts are closed before the main contacts, and the auxiliary contacts are cut off later than the main contacts; the polar plate can be generated when the main contacts are closed and the current is cut off; meanwhile, a power-factor angle detection controlling circuit can automatically detect power-factor angles according to the load conditions of a motor, and the utility model adopts zero crossing triggering technique, so the voltage of motor terminal can be adjusted, the reactive power loss is reduced, and the utility model has an obvious effect of saving energy.

Description

The self adaptation A.C. contactor

The utility model relates to a kind of A.C. contactor, belongs to the threephase motor control device.

Existing A.C. contactor has electric arc and produces when the breaking and closing electric current, and main noddle on contactor can produce arc heat, scaling loss, melting welding phenomenon, and its life-span is shortened dramatically.In addition, motor is owing to the change of load, and when zero load or underloading, power factor is very low between 0.2--0.9, therefore and the electric energy that consumes is very considerable electric efficiency is very low, and reactive loss is big,, for energy-conservation, domestic present use also connects the capacitor local compensation, and is very inconvenient.

The purpose of this utility model is to provide that a kind of main contact can not produce electric arc when the breaking and closing electric current, and can be according to the motor load situation, and the self-regulation motor terminal voltage reduces the self adaptation A.C. contactor of reactive loss.

The self adaptation A.C. contactor that the utility model proposes is the improvement to existing A.C. contactor, and it comprises coil, moving iron core, static iron core, three pairs of main contacts etc.A pole plate links to each other with fixed contact in the two-plate of each phase main contact, and another pole plate links to each other with another fixed contact by the normally closed interlock of relay, and the work of relay is controlled by control circuit.On three pairs of main contacts, an auxiliary contact and damping mechanism are housed respectively, the moving contact of auxiliary contact and the moving contact of main contact and moving iron core all are fixed on the same axis, and opening of the moving contact of auxiliary contact and fixed contact apart from the distance of opening less than the moving contact of main contact and fixed contact, one side of auxiliary contact links to each other with one side of a pole plate of main contact, and another side links to each other with another pole plate of main contact by resistance, voltage-stabiliser tube.One two-way thyristor is housed on each phase main contact, the anode of bidirectional thyristor and negative electrode are connected on respectively on the two-plate of main contact, the control utmost point is connected between above-mentioned resistance and the voltage-stabiliser tube, and links to each other with the output of control circuit, and bidirectional thyristor triggers with the zero passage mode.

Control circuit is that existing power-factor angle detects control circuit.Add the secondary winding that promising control circuit provides operating voltage in the outside of coil.For control circuit provides the transformer of voltage detection signal, the input of its transformer is attempted by on a three-phase neutral point and the phase line.In each phase circuit, the current transformer that the phase current detection signal is provided for control circuit is housed on the main contact bridge circuit.

Cut-off because the utility model adopts auxiliary contact to lag behind main contact prior to the main contact closure, avoided main contact to produce arc phenomenon; Simultaneously, control circuit is according to the motor load situation, and motor terminal voltage is regulated with zero cross fired in detection power factor angle automatically, and reactive loss is reduced.

Below in conjunction with accompanying drawing and practical example the utility model is further described.

Fig. 1 is the control circuit schematic diagram of the utility model embodiment.

Fig. 2 is the control circuit functional-block diagram of the utility model embodiment.

Fig. 3 is the structural representation of the utility model embodiment.

Fig. 4 is the winding diagram of the utility model embodiment.

Fig. 5 is the power circuit principle figure of the utility model embodiment.

With reference to Fig. 3, Fig. 4, present embodiment is improved on the basis of CJ10 or CJ20 A.C. contactor, and its external structure, installation dimension, binding post are constant, have increased arc extinguishing and control circuit board 8 parts.

Arc extinguishing part: above three pairs of main contacts, an auxiliary contact is housed respectively, the moving contact 9 of auxiliary contact and the moving contact of main contact 10 all are fixed on the same axis 3 with moving iron core 2, and the moving contact 9 of auxiliary contact is opened apart from the distance of opening less than main contact moving contact 9 and fixed contact 5 with fixed

contact

6,13, pole plate 15 links to each other with fixed contact in the main contact two-

plate

4,15, pole plate 4 links to each other with fixed contact 5 by the normally closed interlock of relay J, and the work of relay J is controlled by control circuit.One side of auxiliary contact links to each other with one side of the pole plate of main contact 4, and another side links to each other with the another side pole plate 15 of main contact by resistance R, voltage-stabiliser tube D; Slip place in auxiliary contact and axle 3, the spring 11 scribbles damping oil and constitutes damping mechanism, and when electromagnet outage dropout, auxiliary contact hysteresis main contact cut-offs; The anode E of bidirectional thyristor (SCR) 7 and negative electrode F are connected on respectively on the two-

plate

4,15 of main contact, and the control utmost point is connected between resistance R and the voltage-stabiliser tube D.

Control circuit part: add the secondary winding 16 that promising control circuit provides operating voltage in the outside of coil 1; In each phase circuit, the current transformer 14 that the phase current detection signal is provided for control circuit is housed on the main contact bridge circuit.For control circuit provides the transformer of voltage detection signal, its input is attempted by on a three-phase neutral point D and the phase line (A or B or C); Three outputs of control circuit join with the control utmost point of corresponding three bidirectional thyristors (SCR) 7 respectively.

With reference to Fig. 2, control circuit is that control circuit is detected at existing automatic power factor angle, its phase current testing circuit output divides three the tunnel, one the tunnel links to each other with the input of the current detecting delay circuit of control relay operating state, provides the phase current detection signal to the work of current detecting delay circuit with control circuit breaker J; One the tunnel links to each other with the input of zero-cross triggering circuit, provides current zero-crossing signal to zero-cross triggering circuit; The power factor angle detection circuit is sent into through the phase voltage signal behind amplification and rectification circuit that provides with the phase voltage testing circuit behind the amplification and rectification circuit in another road, the output of power factor angle detection circuit links to each other with the input of drive circuit, the output of drive circuit links to each other with the input of zero-cross triggering circuit, and zero-cross triggering circuit produces zero cross signal to control the work of three bidirectional thyristors.

With reference to Fig. 5, its working power is provided after rectification, filtering, voltage stabilizing by the secondary winding 16 on coil 1.

The course of work is: with reference to Fig. 3, wherein integrated package A1-A9 model is 324, the IC2 model is 555, IC3, IC4, when the IC5 model is the energising of TWH9205 self adaptation A.C. contactor, auxiliary contact 9 is connected in main contact 10 in advance, bidirectional thyristor 7 beginning conductings, main contact can not produce electric arc when connecting, electric motor starting, current transformer 14 (B1) induce strong signal, three bidirectional thyristor 7 conductings, but because the connection of main contact, bidirectional thyristor 7 two ends do not have pressure drop, and the electric current of current transformer 14 (B1) is sent into the A8 homophase utmost point, and current potential is higher than the end of oppisite phase current potential that rated current is set W2, A8 is output as height, luminous tube D6 is luminous, and the A9 end of oppisite phase is high, is output as electronegative potential.After motor starting process was finished, electric current dropped to rated value, and the A8 upset is for low, and A9 output is uprised by low, the relay J adhesive, and the normally-closed contact that is serially connected in the main contact 10 disconnects, and electric current just relies on three bidirectional thyristor 7 conductings.By the electric current of current transformer 14 (B1), provide current zero-crossing signal to IC3 on the one hand, after A1 amplifies, send into comparator A2 on the other hand, sending with zero at the output of A2 is the positive half cycle square wave of initial point; Phase voltage signal by transformer B2 be coupled to secondary after, send into A4, A5, A6 cascade amplification, voltage signal after the amplification is sent into comparator A7, sending this at the output of A7 is the positive half cycle square wave of voltage of initial point with zero, electric current and voltage signal obtain an average voltage at the in-phase end of A3 after the AND circuit that D2 and D3 form is synthetic.Supply with time-base circuit ic chip 2 by the average voltage that the A3 output is sent, IC2 is that one-period is a 15MS square wave multivibrator, its duty ratio is controlled by the 5th pin voltage, when the 5th pin voltage is high, point is empty than increasing, duty ratio is little when low, give zero cross fired ic chip 3 by the controlled duty cycle square wave that IC2 the 3rd pin is sent, IC4, IC5, by current transformer 14 (B1, B3, B4) give IC3, IC4, one of IC5 the 5th pin is routine zero cross signal, at the controlled square wave of IC2 the 3rd pin is timing, bidirectional thyristor SCR is carried out zero cross fired, and the controlled square wave of IC2 output has determined the chance of bidirectional thyristor SCR zero cross fired, when power factor is low, A3 output voltage step-down, the IC2 duty cycle square wave diminishes, IC3, IC4, the zero cross fired signal of IC5 output reduces, and motor terminal voltage reduces; (as set point is 0.7 for the boundary, surpasses 0.7) A3 output voltage increases when power factor increases, and the IC2 duty cycle square wave increases to maximum, IC3, IC4, the continuous zero cross fired signal controlling bidirectional thyristor SCR work of IC5 output.

Claims

1, a kind of self adaptation A.C. contactor, it comprises coil (1), moving iron core (2), static iron core (17), three pairs of main contacts etc.; It is characterized in that:

A pole plate (15) links to each other with a fixed contact in the two-plate of main contact (4,15), and another pole plate (4) links to each other with another fixed contact (5) by the normally closed interlock of relay, and the work of relay is controlled by control circuit;

Auxiliary contact and damping mechanism are housed on the main contact, the moving contact (10) of moving contact of auxiliary contact (9) and main contact all is fixed on the same axis (3) with moving iron core (2), and opening of the moving contact of auxiliary contact (9) and fixed contact (6,13) apart from the distance of opening less than moving contact (10) with the fixed contact (5) of main contact, one side of auxiliary contact links to each other with one side of a pole plate (4) of main contact, and another side links to each other with another pole plate (15) of main contact by resistance, voltage-stabiliser tube;

Bidirectional thyristor (7) is housed on the main contact, and the anode of bidirectional thyristor (7) and negative electrode are connected on respectively on the two-plate (4,15) of main contact, and the control utmost point is connected between above-mentioned resistance and the voltage-stabiliser tube, and links to each other with the output of control circuit.

2, self adaptation A.C. contactor according to claim 1 is characterized in that: the current transformer (14) that the phase current detection signal is provided for control circuit is housed on the main contact bridge circuit; The outside of coil (1) adds promising control circuit provides the secondary winding of operating voltage (16); For control circuit provides the transformer of voltage detection signal, the input of its transformer is attempted by on a three-phase neutral point and the phase line.

3, self adaptation A.C. contactor according to claim 2, it is characterized in that: control circuit is that power-factor angle detects control circuit, its phase current testing circuit output divides three the tunnel, the one tunnel to link to each other with the input of the current detecting delay circuit of control relay work; One the tunnel links to each other with the input of zero-cross triggering circuit; Another road links to each other with the input of power factor angle detection circuit behind amplification and rectification circuit; The output of phase voltage testing circuit links to each other with the input of amplification and rectification circuit, the output of amplification and rectification circuit links to each other with the input of power factor angle detection circuit, the output of power factor angle detection circuit links to each other with the input of drive circuit, the output of drive circuit links to each other with the input of zero-cross triggering circuit, and zero-cross triggering circuit produces zero cross signal to control the work of three bidirectional thyristors (7).