CN2137833Y - Fully automatic protection device for electric motor - Google Patents

Abstract

The utility model relates to a protector of an electric motor, which has high stability and reliability. The fully automatic protector for an electric motor is provided with multiple protective functions, such as overload protection, loss of phase protection, over-voltage protection, under-voltage protection, short-circuit protection, etc. The utility model is characterized in that a detecting voltage provided by a detecting element applies bias current to a driving circuit of a two-stage relay which is composed of triodes, different faults are corresponding to different detecting signals which are filtered and converted to drive a controlled executive circuit to make the controlled executive circuit act. Meanwhile, messages of an over-voltage and under-voltage identification circuit are input into the controlled executive circuit to make the controlled executive circuit act likewise, and thus various protective functions are achieved. The utility model has the advantages of simple structure, low cost, and convenient installation and operation.

Description

Fully automatic protection device for electric motor

In addition many-sided multi-function protector of protection automatically when the utility model relates generally to a kind of can the operation motor; It has adopted new method to realize various defencive functions on circuit and working method; especially the contactor dividing potential drop mode of connecting with resistance-capacitance network has been adopted in the extraction of working line working power; the supply voltage of getting is directly proportional with the motor operating voltage; provide signal for the ultra under-pressure circuit easily; the mode of setting up of this power supply can also be used for the others circuit, has higher promotion and application and is worth.

In the existing motor protecting device, can be divided into single function and multi-functional two kinds on the purposes, the protective device of function singleness is because its safeguard measure imperfection and being eliminated gradually; With the continuous development of science and technology, transistor, integrated circuit motor protective device occur in succession, and function improves gradually.But structure is also complicated more, the also corresponding increase of cost, and most of protective devices are by the resistance step-down and have used independent power transformer to provide working power for protection circuit that this has not only wasted electric energy and raw material, and the life-span of device is restricted.Number of patent application " 87205604 " " threephase motor overload and open-phase protection device " is though played the certain protection effect; but with regard to operation principle; be difficult for increasing again other functions; and fault and large-size machine are unloaded to differ several times with fully loaded current of electric when motor is short-circuited; even it is bigger; this just means that the relay both end voltage also can differ several times, and the saturation current that obvious two triodes pass through is also very high, and this all is improper.

The purpose of this utility model promptly produces thus; Provide a kind of reliability higher motor protector.

The utlity model has overcurrent, short circuit, superpressure, kinds of protect function such as under-voltage; also have characteristics simple in structure, with low cost, saves energy; easy to install, long service life not only are applicable to the threephase motor of any size also to be applicable to single-phase AC motor.

Task of the present utility model is finished like this:

The detection voltage that is provided by detecting element applies bias current for the two poles of the earth relay execution drive circuit that triode is formed simultaneously; different faults has different detection signals; the controlled executive circuit of wave conversion rear drive makes its action after filtration; information from the ultra under-pressure identification circuit also is input to controlled executive circuit simultaneously; make it make same response, thereby finish various defencive functions.

The principal character of the utility model circuit is: have signal deteching circuit; controlled executive circuit; capacitance-resistance dividing voltage supply circuit and operation circuit etc.; by three induction coils 1 and diode 2; filter capacitor 3 is formed the overload of loss of phase testing circuit; divider resistance 4 and adjustable resistance 5 series connection are also taken out detection voltage by resistance 5 central shaft heads and are passed through the series connection superpressure; overcurrent isolating diode 26 is connected to triode 9 base stages; biasing resistance 7 is connected in series in biasing resistance 8 and drives triode 13 base stages; triode 13 collector electrodes are connected to relay 12; voltage stabilizing didoe 10 positive termination triode 9 base stages of superpressure signal are provided and connect and finish superpressure and detect with triode 9 emitter junctions; its negative terminal is connected to the 12V power positive end; under-voltage sampling triode 14 base stages connect dividing potential drop variable resistance 16 centre caps; the series resistance 7 of bias current is provided for triode 13; be connected to PNP triode 14 emitters in the middle of 8; rectification full-bridge 18 provides 12V DC power supply for protection circuit; electric capacity 19; 20 are composed in series polarity free capacitor; two ends are respectively in parallel again as the resistance 21 of balance two capacitance terminal voltages; 22; this resistance-capacitance network is connected in the middle of the whole operation loop; the dividing potential drop of promptly connecting with contactor coil 25 is formed the capacitance-resistance dividing voltage supply and is extracted circuit.

Three instrument transformers that are used for testing circuit are to use the enamelled wire that is wound with certain number of turn on the magnet ring, are advisable with 500 circles.

The electric capacity 11,15 that is connected to triode 13,14 base stages in the middle of the circuit is anti-interference capacitor, and the electric capacity 6 that is connected to triode 9 base stages is the overload delay capacitor, suitably selects electric capacity 6 to change and transships operate time.

The utlity model has following characteristics:

1, simple in structure, multiple functional, have various defencive functions such as overload, open phase protection and superpressure, under-voltage, short circuit, the especially single-phase function that do not start is popular.

2, operating voltage range is wide, owing to adopted the capacitance partial pressure supply power mode, has saved power transformer, makes this machine cost＜10 yuan, is the least cost limit of like product.

3, a tractor serves several purposes, by different connecting modes, can be single-phase, three-phase, motor, generator, supply transformer make overload protection and use with any size.

4, connection is simple, easy to use, is provided with the capacity regulating knob, can be advantageously used in different occasions.

5, long service life, stream time are more than 100,000 hours.

6, make former control circuit power consumption reduce 1.5W, belong to the electricity-saving type product.

The utility model embodiment provides two accompanying drawings.

Accompanying drawing 1 is the utility model circuit block diagram.

Accompanying drawing 2 is the utility model electrical schematic diagram.

As shown in Figure 1, the utility model is made of circuit such as signal deteching circuit, controlled executive circuit, capacitance-resistance dividing voltage supply circuit and operation circuits.

Describe the utility model circuit structure interworking process in detail below in conjunction with accompanying drawing 2:

1, signal deteching circuit: this part induces a voltage by three string heart mutual inductor serials and obtain one with the big or small direct voltage that is directly proportional of motor current at 3 two ends after 3 filtering of diode 2 halfwave rectifier capacitors, the phase failure is to this loss of voltage, and is higher when this voltage increases, short circuit during overcurrent.Simultaneously testing circuit also comprises superpressure and the under-voltage sample circuit of being made up of voltage stabilizing didoe 10 and PNP and triode 14 and variable resistance 16, anti-interference capacitor 15.

2; controlled executive circuit: this circuit is imported as signal by triode 9; triode 13 is finished as the relay controlling unit; electric capacity 3 both end voltage raise when overcurrent and short circuit; resistance 4 and adjustable resistor 5 centre cap dividing potential drops are also high; by electric capacity 6 time-delays; be added in triode 9 base potential rising triodes 9 saturation conductions; making the base voltage that is provided by resistance 7 and resistance 8 of triode 13 reduce to 0.3V 13 is ended by conducting state; relay 12 discharges; the contactor decompression; the motor outage; capacitor 3 both end voltage fall zero during the phase failure; triode 13 base stage no-biases and ending; finish the protection action; cause the motor voltage rising to be for a certain reason; also raise by the DC line operating voltage that obtains at electric capacity 17 two ends after the resistance-capacitance network dividing potential drop rectification of connecting with contactor; voltage stabilizing didoe 10 beginning conductings; one part of current flows through the base stage of triode 9; triode 9 conductings; 13 end again; repeat above-mentioned action; if motor is in under-voltage condition work; electric capacity 17 both end voltage reduce; variable resistance 16 center drawer's current potentials also reduce; triode 14 beginning conductings; the resistance 7 of bias voltage is provided for triode 13; voltage between 8 is reduced to 0.3V; 13 lose bias voltage and end; relay 12 discharges; the contactor outage, motor is under-voltage to be protected.

3, capacitance-resistance dividing voltage supply circuit: this circuit is formed a series connection polarity free capacitor by electrolytic capacitor 19,20 and is series in the contactor coil 25 after by resistance 21,22 balanced voltages, the appearance resistance effect of alternating current is got-12V voltage during owing to electric capacity, provides working power by rectifier bridge 18 rectifications for relay 12 and ultra under-pressure sample circuit.

4, operation circuit: this loop is made up of start button 24 and stop button 23 and relay normally open contact and contactor normally opened contact and contactor coil, press the QA24 contactor and get electric adhesive, the motor operation, relay drives adhesive normally opened contact closure by triode 13, the attached normally opened contact that helps of contactor is also closed, the control loop self-locking is opened its normally opened contact J because of certain fault causes the actuating of relay _0-1, contactor will cut off the power supply, and is same, presses TA stop button 23, and contactor also quits work, and motor is out of service, realizes operating function.

Claims (3)

1; a kind of full-automatic electric motor protector; has signal deteching circuit; controlled executive circuit; the capacitance-resistance dividing voltage supply extracts circuit and operation circuit; it is characterized in that by three induction coils 1 in diode 2; filter capacitor 3 is formed the overload of loss of phase testing circuit; divider resistance 4 and adjustable resistance 5 series connection are also taken out detection voltage by resistance 5 centre caps and are passed through the series connection superpressure; overcurrent isolating diode 26 is connected to triode 9 base stages; biasing resistance 7 is connected in series in biasing resistance 8 and drives triode 13 base stages; triode 13 collector electrodes are connected to relay 12; voltage stabilizing didoe 10 positive termination triode 9 base stages of superpressure signal are provided and connect and finish superpressure and detect with triode 9 emitter junctions; its negative terminal is connected to the 12V power positive end; under-voltage sampling triode 14 base stages connect dividing potential drop variable resistance 16 centre caps; the series resistance 7 of bias current is provided for triode 13; be connected to PWP triode 14 emitters in the middle of 8; rectification full-bridge 18 provides 12V DC power supply for protection circuit; electric capacity 19; 20 are composed in series polarity free capacitor; two ends are respectively in parallel again as the resistance 21 of balance two capacitance terminal voltages; 22; this resistance-capacitance network is connected in the middle of the whole operation loop; the dividing potential drop of promptly connecting with contactor coil 25 is formed the capacitance-resistance dividing voltage supply and is extracted circuit.

2, full-automatic electric motor protector according to claim 1 is characterized in that: the electric capacity 11,15 that is connected to triode 13,14 base stages in the circuit is anti-interference capacitor, and the electric capacity 6 that is connected to triode 9 base stages is the overload delay capacitor.

3, full-automatic electric motor protector according to claim 1 is characterized in that: three instrument transformers 1 that are used for testing circuit are to be made by the enamelled wire that is wound with certain number of turn on the magnet ring, and its number of turn is preferably 500 most.