CN2185000Y

CN2185000Y - Three phase circuit protector

Info

Publication number: CN2185000Y
Application number: CN 94206464
Authority: CN
Inventors: 郭�东
Original assignee: Hengda Science And Tech Development Co Huabei Petroleum No1 Mechanical Facto
Current assignee: Hengda Science And Tech Development Co Huabei Petroleum No1 Mechanical Facto
Priority date: 1994-03-09
Filing date: 1994-03-09
Publication date: 1994-12-07
Anticipated expiration: 2004-03-09

Abstract

The utility model discloses a three phase circuit protector, relating to a circuit protecting device when the three phase electric drive system occurs phenomena of the phase lacking, the over current, and loss of voltage (undervoltage). The circuit protecting device is composed of a signal measuring and taking circuit, a signal processing circuit, a time delay circuit, a power cut signal processing circuit, an operation serve circuit, and a power circuit which are connected. The utility model has multiple functions and multiple uses, and the performance is reliability. The delay time of the protecting action can be completed within a few seconds, and the protective effect is very good. The utility model has the advantages of small structure and low cost. The volume, the weight, the cost, etc. can reduce more than 90%, and the self electricity consumption can reduce more than 98%.

Description

Three phase circuit protector

A kind of circuit protection device when the utility model relates to three-phase power dragging system generation phase shortage, overcurrent and mistake (owing) pressure.

At present, the three-phase power dragging system in the Induction Motor Control circuit, carries out protections such as short circuit, overload, phase shortage, mistake (owing) pressure in order to reach to motor, circuit, needs to adopt distribution box (cabinet).Distribution box (cabinet) generally is combined into relay type protective device by on-load switch, fuse or automatic switch, relay, contactor etc.The sort circuit protective device, not only complex structure is bulky, the cost height, self power consumption is many etc., nor is suitable for the place of field, particularly unsupervised to be used; The more important thing is relay type protective device; usually all adopt thermal relay then to get parts as the signal of motor overload protection; for the big motor of the fluctuation of load,, carry out overload protection with thermal relay as the used motor such as oil pumper of sandstone crushing machine, recover petroleum; protective device also fails to move often; motor is burnt already, and the speed of protection is too slow, and the delay time reaches more than the dozens of minutes to hour; sensitivity and reliability are relatively poor, and actual unprotect can be sayed.

The purpose of this utility model is to avoid the deficiencies in the prior art part, and provides a kind of structure small and exquisite, makes low inexpensively, protects reliable Mobyneb circuit protection device.

Can take following technical scheme to realize purpose, measure circuit, signal processing circuit, delay circuit, power-off signal treatment circuit, action servo circuit and power circuit by electronic signal and connect and compose three-phase circuit phase shortage, overcurrent and mistake (owing) pressure multifunctional protection device.

In conjunction with the accompanying drawings, execution mode is described in further detail the content of the technical program.

Accompanying drawing is a kind of electrical schematic diagram of this three-phase circuit protector.

Its signal measures circuit by inductance L, L1-L3, and corresponding triode BG1, diode D1, D2 and resistor-capacitor unit W1, R1, C1 are formed by connecting.Adopt current transformer spare and electronic switching device to be the electric current in the main circuit is changed the voltage signal output that is converted into the electronic switching device conducting or ends.L is the overcurrent instrument transformer, and L1, L2, L3 are the phase shortage current transformer.Signal processing circuit is by integrated operational amplifier or logic element BG2, and diode D3, K switch and resistor-capacitor unit W2, R3-R9, C2 are formed by connecting.Signal processing circuit measures after voltage signal that circuit transmission comes handles signal, is transferred to the action servo circuit with high level, low level signal form; In addition, devices such as the K in the circuit, C2, R4, R6, R8, W2 are to form the signal damping circuit, under " filtering " certain load, controlled main circuit might appear in short-term during no current, measure " malfunction " signal that circuit transmission is come by signal, holding circuit stable.Delay circuit is by triode BG3, BG4, voltage stabilizing didoe D5, D7, and diode D6, D8, controllable silicon T1 and resistor-capacitor unit R11-R15, C3-C5 is formed by connecting; After its effect is power connection, action servo circuit time-delay is devoted oneself to work, the power-off signal treatment circuit is by triode BG5, diode D10, and voltage stabilizing didoe D11 and resistance R 16 are formed by connecting; It converts the signal that promotes the work of next stage action servo circuit to power supply " having " and " nothing ".Move servo circuit by DT, diode D12, D13, controllable silicon T2 and resistor-capacitor unit R17, R19, C6, C7 are formed by connecting.The conversion of signals that it comes the upper level circuit transmission becomes " conducting ", " ending " or certain mechanical action of circuit.DT in the circuit can be electronics or electromechanical device, as controllable silicon, relay, electromagnet and other device; Its effect is in order to start or to order about actuator's action-tripping operation of the control apparatus of main circuit; The concrete form of DT can be taken the circumstances into consideration selected by the control apparatus that is pushed as switch, contactor etc.DT in the illustrated example is a servo magnet.Action go out R17, D13 in the servo circuit and C7 forms accumulator, to guarantee that after main circuit has a power failure the servo circuit that moves still can be finished specific action.Power circuit is formed by connecting by diode D4, D9 and resistance R 10, and its adopts three-phase electricity to power for this device, so when a certain when cutting off the power supply mutually, this device endure.

When the control apparatus of this protector and main circuit makes up, three phase lines can be passed from the hole of L1, L2, L3 respectively, any phase line is passed from the hole of L again, to make the primary winding of instrument transformer, as existing core-theaded type current transformer is installed.A among the figure, b, three the end of a thread of c are connected on respectively through on three phase lines behind the main circuit control apparatus, "

" receive on the zero line of power supply.

When the control apparatus of main circuit was connected three phase mains, three-phase electricity was powered for this protector after the D4 of this device power circuit rectification and it is devoted oneself to work.In the moment that rigidly connects energize, delay circuit plays the on-delay effect immediately, and action servo circuit locking, after time-delay was finished, T1 conducting, action servo circuit just can enter servo armed state; At this moment the whole protecting device all enters normal operating conditions, in case actuating signal is arranged, the action servo circuit can be carried out " task ".

Overcurrent (overburden) protection.When the electric current in the controlled circuit was within setting value, the signal deficiency that L exported was so that signal measures circuit operation, and circuit is kept stable; When electric current surpassed setting value, the signal that L exported will be above a certain threshold value, and this signal triggers controllable silicon T2 through D3, R18 again after signal processing circuit is handled, and made servo magnet DT action, control apparatus tripping operation.

Open-phase protection.When all having electric current to pass through in the three-phase circuit, three switching tubes of BG1 all are in conducting state, at this moment obtain a low level in the R4 upper end, and circuit is not triggered, and keeps operate as normal; When three phase mains lacks an electricity or when making in a certain circuitry phase no current because of certain reason mutually, there is one signal out of hand is cut off in three pipes of BG1, at this moment will obtain a high level in the R4 upper end, this level triggers T2, servo magnet DT action, control apparatus tripping operation through D3, R18 after signal processing circuit is handled.If a certain phase voltage of three-phase electricity is low excessively, when promptly three-phase electricity was seriously uneven, circuit also can be triggered and make the control apparatus tripping operation.

Lose (owing) and press protection.When supply voltage just often, the BG5 conducting, the D10 place obtains a low level, circuit is in steady-working state; When the power supply sudden power, be decompression, or three-phase voltage is reduced to suddenly below the numerical value, when promptly under-voltage, BG5 ends, the high level signal at D10 place triggers T2, servo magnet DT action through R18, the control apparatus tripping operation.

Short-circuit protection and earth leakage protective.When this protector is used in combination with automatic air-break switch or leakage switch, its short circuit, earth leakage protective is finished by the trip gear of air switch, leakage switch.If the defencive function of air switch, leakage switch is malfunctioning, the overcurrent protection of this three-phase circuit protector also can make the control apparatus tripping operation.

In the signal processing circuit of this protector, be provided with selector switch K, in order to satisfy the actual needs of protected electrical equipment.When protected asynchronous motor drag be normal load the time, K switch places open position; What drag when asynchronous motor is the potential energy load, promptly in the motor course of work, the load of the anti-drive motor of load might appear, oil pumper even load as crane, recover petroleum, at this moment, K switch should place make position, and adjusts lag time of signal processing circuit acknowledge(ment) signal by W2, to prevent the circuit false triggering.Because during the anti-dragging motor of load, the rotating speed that makes asynchronous machine sometimes is near synchronous speed, electric current in the circuit is often very little at this moment, can make and measure signal circuit output false triggering signal in short-term, as long as the time that this false triggering signal keeps is not more than the time of the hysteresis acknowledge(ment) signal that signal processing circuit sets, can not moved by false triggering just can guarantee circuit.

The relative prior art of the technical program has following advantage:

1, multi-functional, multipurpose: this device has preferably overcurrent (overburden) protection, open-phase protection, mistake (owing) pressure protection several functions; This device also can be contained in the automatic air-break switch, leakage switch is interior and the corresponding multifunction switch of its composition; Also can be contained in the distribution box (cabinet), directly drive control apparatus in order to replace the relay protection part; Also can be used as the master switch use that transformer low voltage is surveyed.

2, dependable performance: various duties, use are needed all can effectively protect; especially the overcurrent protection of this device and open-phase protection; snap action; even make signal processing circuit be in hysteresis acknowledge(ment) signal state; its protection action delay time also only finished within several seconds, and the protection effect is very outstanding.

3, structure is small and exquisite, cheap: in some middle-size and small-size three-phase power dragging systems, form multifunction switch with this device with automatic switch, replace the distribution box (cabinet) of existing relaying protection type, not only feasible, and can make the volume, weight, cost etc. of electric control gear reduce more than 90%; Self power consumption of electric control gear can reduce more than 98%.Especially for the open-air or roving gadget of unsupervised, the anti-destructive of this device, just mobility all is much better than existing protective relaying device.

Claims

1, a kind of three-phase circuit protector is characterized in that: it is to measure the circuit protection device that circuit, signal processing circuit, delay circuit, power-off signal treatment circuit, action servo circuit and circuit source circuit connect and compose by signal.

2, three-phase circuit protector as claimed in claim 1 is characterized in that: its signal measures circuit by inductance L, L1-L3, corresponding triode BG1, and diode D1, D2 and resistor-capacitor unit are formed by connecting; Signal processing circuit is by integrated operational amplifier or logic element BG2, diode D3, and K switch and resistor-capacitor unit connect and compose; Delay circuit is by triode BG3, BG4, voltage stabilizing didoe D5, D7, and diode D6, D8, controllable silicon T1 and resistor-capacitor unit are formed by connecting; The power-off signal treatment circuit is by triode BG5, diode D10, and voltage stabilizing didoe D11 and resistance R 16 are formed by connecting; Move servo circuit by DT, diode D12, D13, controllable silicon T2 and resistor-capacitor unit are formed by connecting; The three phase supply power circuit is connected and composed by diode D4, D9 and resistance R 10.