CN2177297Y - Multifunction three phase motor power supply protective box - Google Patents

Abstract

The utility model discloses a protective box which is the development and the perfection of a supply protection box for a three-phase motor, comprising a power input end, the actuating mechanism of a switch and protective actions, an AC contactor, the sample circuit of motor current amplitude value, the sample circuit of the voltage of a motor power supply line, the voltage power amplification circuit of amplifying sampled signals, an output end, etc. The protective box adopts fixed voltage as comparison voltage at the input end of a rectifying bridge stack, which solves the motor protection problem when three phases simultaneously have over current fault. The utility model has the advantages of safety, durability, easy commercialization, etc.

Description

Multifunction three phase motor power supply protective box

The utility model relates to motor protecting device, particularly relates to a kind of threephase motor protective device.

The protection of threephase motor is the important and stubborn problem of power industry always.The damage of overwhelming majority threephase motors is not all in time handled and is caused owing to faults such as phase shortage or overcurrents.Although released the protector of many kinds on the market, this protector generally all is the situation according to concrete that motor of protecting, designs its protection circuit targetedly.Majority all adopts microelectronics, integrated circuit, and institute spends a lot of time and energy many, and reliability is but often not good enough.Because user of all kinds does not generally possess peripheral guaranteed conditions such as voltage stabilizing, isolation, shielding, filtering; abominable electric circumstance, microelectronic one occurring once overlaps and may integral body scrap; this is fatal weakness, thus people often without what protector, motor has been broken and has been repurchased one.But for the motor of those large-scale keys, just must consider safeguard measure, the protection of most employing temperature-sensitive element.Experienced a period of time yet this protection is actually in accident, the insulation of motor winding is impaired, and just the signal that is detected by temperature-sensitive element is realized, therefore the effect of this protection is nothing but to bear several times more.Allow the operator on duty day and night guard besides, rotate cacophonia, just hasten to operate a switch in case hear motor.Currently have to solve problem, the present situation of Here it is motor protection with these ways.

It is that 92233881.7 Granted publications number are the threephase motor power supply protection case of CN2128426Y that the inventor has invented China Patent No.; electric current, voltage ratio have been used than the type protection philosophy; result relatively makes when motor emerged in operation fault, produces a big signal of output amplitude and goes to promote relay realization protection.Another characteristics are to make the key electronic devices and components that shield in the circuit; under normal power supply, be in " rest " state (being low power consumpting state); only just in running order in phase shortage (phase failure), overvoltage, under-voltage of short duration moment; thereby electronic devices and components are durable in use; it reliablely misoperation can not occur in addition; the deficiency of just having got rid of aforementioned all points can stand the test of the various electric circumstances of different user, continuously long-term charging operation.

; this power supply protection case; because in three current transformers of its current amplitude sample circuit; first; 3 two current transformers are respectively with the rectifies on single the rectifying circuit; convert two direct voltages then to; second current transformer placed in the middle then is with the rectification respectively of two rectifying circuits; convert two identical direct voltages then to; then the direct voltage of first current transformer after a rectification on the direct voltage after the rectification and second current transformer is input to two inputs that first rectifier bridge is piled respectively; another commutated direct current on second current transformer is pressed; press with the commutated direct current on the 3rd current transformer; be input to two inputs of second rectifier bridge heap respectively; circuit with this structure; in when, simultaneously over current fault taking place on its three current transformers when; no matter the overcurrent amplitude has much; two inputs of each bridge heap during two bridges are piled; the commutated direct current of one end input presses the commutated direct current of making comparisons with the usefulness of other end input to press; always produce unconspicuous voltage difference; thereby just not producing signal output at the output of bridge heap, this protection has just lost effect.So have the current amplitude sample circuit of sort circuit structure, its power supply protection case does not just have the function of overcurrent, overload, rotation-clogging protection, and is from the viewpoint of general protection motor, just not ideal enough.

The purpose of this utility model is; for widely used three-phase alternating-current motor in the industrial and agricultural production provides a kind of not only safe and effective but also practical durable; defencive function is more complete, and the user uses again easily power supply protection equipment-multi-functional (phase shortage, overvoltage, under-voltage, overcurrent, stall, etc.) threephase motor power supply protection case.

The utility model power supply protection case is that the patent No. is the development and perfection of 92233881.7 threephase motor power supply protection box technologies.It is the voltage sample circuit by power input, switch and protection action actuating mechanism, A.C. contactor, motor current amplitude sample circuit, motor supply line, amplifies the voltage power amplifying circuit of sampled signal and partly forms in order to the output that connects motor etc.

By circuit and switch and protection action actuating mechanism, A.C. contactor joins power output end respectively; Switch also joins by the voltage power amplifying circuit of circuit and A.C. contactor, amplification sampled signal respectively with the protection action actuating mechanism; A.C. contactor also connects the voltage sample circuit of motor supply line, also pass each current transformer in the motor current amplitude sample circuit by one group of circuit after, directly join with the power supply protection case output that is connected motor; Motor current amplitude sample circuit then has circuit to link to each other with the voltage power amplifying circuit that amplifies sampled signal in addition; And the voltage sample circuit of motor supply line, except that having aforementioned circuit connects, also link to each other with the voltage power amplifying circuit that amplifies sampled signal by another group circuit.Connect the organic whole that has just formed multi-functional power supply protection case by these circuits.

The structure of motor current amplitude sample circuit of the present utility model is different with 92233881.7, it is characterized in that joining three current transformers with three rectifier bridge heaps and a three terminal regulator.Each current transformer all is divided into two rectifying circuits, one props up the input that direct voltage is transported to a rectifier bridge heap after the rectification, another commutated direct current is pressed and then is transported to a shared three terminal regulator (for example according to the actual current of threephase motor, can choose 7808 or three terminal regulator such as 7805.7806.7809.7812) input, the voltage of again certain selected dc voltage value of its output being made comparisons, be transported to another input of same rectifier bridge heap, the output of this bridge heap then joins with the input of a photoelectrical coupler.This circuit can be transported to direct voltage an input of rectifier bridge heap by the detected threephase motor induced current of current transformer after rectification, and with another input on chosen dc voltage value make comparisons.Under normal circumstances, two input terminal voltage differences of rectifier bridge heap are almost nil, and photoelectrical coupler does not produce signal output.In case over current fault (comprising three-phase overcurrent simultaneously) takes place in mutually; two inputs at the rectifier bridge heap that is associated with that phase current mutual inductor; will produce tangible voltage difference; output just has voltage and is input to generation signal output on the photoelectrical coupler; triode amplifies, makes controllable silicon conducting, relay by adhesive action control switch and protection action actuating mechanism in amplifying circuit again, causes the A.C. contactor tripping operation.Power supply protection case with this current amplitude sample circuit, to phase shortage, single-phase or two-phase crosses, under-voltage, overcurrent, faults such as stall short circuit can both realize the effective protection to motor.When having solved 92233881.7 pairs of three-phases well and simultaneously over current fault taking place, can not carry out the difficult problem of protection to motor.

Another feature of the present utility model is the voltage sample circuit of its motor supply line, is different from 92233881.7 voltage sample circuit, and it joins two miniature transformers by a rectifier bridge heap and three three terminal regulators.The major loop of each transformer is all received respectively in 220 volts of supply lines, and the secondary loop all is by there being tapped two windings to constitute.First transformer TRA ₁, the upper end tap of secondary loop, three rectification circuits in parallel, second transformer TRA ₂The upper end tap parallel connection of secondary loop two rectification circuits, transformer TRA ₁First rectification circuit of upper end tap is transported to the 4th rectifier bridge heap BR to the direct voltage after the rectification ₄An input, transformer TRA ₁Second rectification circuit of upper end tap and transformer TRA ₂Connect second three terminal regulator (for example 7824 etc.) circuit after first rectification circuit parallel connection of upper end tap, a fixed value voltage of its output is transported to rectifier bridge heap BR ₄Another input voltage of making comparisons, this rectifier bridge heap BR ₄Pair of output then with the 4th photoelectrical coupler OPT ₄Input link to each other; And transformer TRA ₁The 3rd rectification Mian road of upper end tap and transformer TRA ₂Connect the 3rd three terminal regulator (for example 7824 etc.) circuit after the second rectification circuit parallel connection of upper end tap, the fixed value voltage of output is made auxiliary relay and silicon controlled operating voltage; Transformer TRA ₁With TRA ₂The rectification circuit that centre tap connected of secondary loop, back in parallel connects the 4th three terminal regulator (for example 7809 etc.) circuit, and the fixed value voltage of output is as the needed operating voltage of triode in the output of four photoelectrical couplers in the utility model and the amplifying circuit.In case it is simultaneously under-voltage or cross simultaneously and take by force that three-phase appears in power circuit, then in having supply line's voltage sample circuit of this line construction, will be at transformer TRA ₁On first rectifying circuit of upper end tap, correspondingly occur lower or higher voltage is transported to rectifier bridge heap BR ₄An input, make comparisons with the fixed value voltage of another input, a bigger voltage difference is arranged, thereby photoelectrical coupler OPT ₄Signal output is just arranged, trip, realize effective protection motor through amplification, controllable silicon conducting, auxiliary relay action, A.C. contactor.This point, the utility model is a a progressive step than 92233881.7 again.

The same with 92233881.7, the voltage power amplifying circuit of amplification sampled signal of the present utility model is also extremely managed amplifying circuit, direct current controllable silicon and auxiliary relay by three and is formed.Negative pole, emitter that the base stage of triode connects output in the photoelectrical coupler connect the silicon controlled control utmost point, and collector electrode connects standard direct-flow positive voltage (output of three terminal regulator).This circuit can be because of phase shortage; single-phase or two-phase crosses, under-voltage; overcurrent; faults such as stall short circuit and the small-signal that in motor current amplitude sample circuit, produces; or three characteristics of the middle term overvoltage or the under-voltage fault of three-phase and the small-signal that in motor supply line voltage sample circuit, produces; by amplification, conducting controllable silicon and auxiliary relay, come control switch and protection action actuating mechanism.

For high-power threephase motor (such as 3000 volts, 6000 volts threephase motor), use the utility model power supply protection case to be protected effectively, these need are changed slightly on the line and just can be realized: high-voltage motor is received on the high voltage source by the high-voltage alternating contactor; And three current transformers in the motor current amplitude sample circuit will adopt high-tension current inductor and change and fit on the high-tension line; All the other line constructions of this power supply protection case are not changed, and required common 380 volts/220 volts voltages are supplied with by the transformer step-down by high voltage source.

Advantage of the present utility model is: (one) defencive function is more complete, applied range.When various faults such as phase shortage, overvoltage, under-voltage, overcurrent, stall, short circuit take place on threephase motor or power circuit when; it can both be to electrical motors to protective effect effectively; and it both be applicable to several kilowatts in hundreds of kilowatt, small size motor, also be suitable for as high pressure high power motors such as 3000 volts, 6000 volts.(2) practical durable.In this power supply protection case; the basic discrete component of generally using always in electrotechnics and the electronics that adopts; all other protector of the integrated package combination compared of charging operation for a long time is durable for they; and the crucial electronic devices and components of the main actuator that shields; as rectifier bridge heap, photoelectrical coupler; controllable silicon; triode etc.; under long normal power supply situation; be in resting state (low-power consumption); only just work in the moment of breaking down, this has just guaranteed more durable in use than other protector.(3) described as 92233881.7, the utility model power supply protection case is easy to realize commercialization.Thereby existing protector protects the power of electric motor narrow range, and the occasion that the protector of a specification can use is few.The following motor of 300KW power for example, the protector that has has used twenties kinds of specifications also not have can be topped whole power interval.Therefore, the electrician shop is difficult to get all the ready the goods of hoarding numerous like this specifications and selects for the user, and the utility model only just can satisfy the needs of various large, medium and small type motor protections with several specifications.

The utlity model has following accompanying drawing.

Fig. 1 is a multi-functional threephase motor power supply protection device line map (it is applicable to the protection of 380 volts/220 volts of common motors).

Fig. 2 is the line map (it is applicable to the protection of high voltage and high power electromotor) of multi-functional another embodiment of threephase motor power supply protection case.

Below in conjunction with accompanying drawing the utility model is further specified.

Embodiment 1

As shown in Figure 1, for being suitable for the multi-functional threephase motor power supply protection case of 380 volts/220 volts of common motors.Three-phase power input end is L ₁, L ₂, L ₃, A.C. contactor CJ ^* _1-4With indicator light LA ₁, CJ ^* _1-5With indicator light LA ₂Series connection respectively, again with both parallel connections, back one end in parallel and L ₁Connection, the other end are connected with center line N; Relay J _NWith start button AN ₁After the parallel connection, one end and stop botton AN ₂, midget relay MJ _H, auxiliary relay J ₁In sequential series, and AN ₁With J _HThe other end and L in parallel ₁End connects, auxiliary relay J ₁The other end be connected with center line N; Relay J _1-2, A.C. contactor CJ ^* ₁, relay J _1-3Series connection successively, its J _1-2The other end and L ₂End connects, J _1-3The other end be connected with center line N; A.C. contactor CJ ^* _1-1, CJ ^* _1-2, CJ ^* _1-3An end respectively with L ₁, L ₂, L ₃End connects, relay J _2-4With indicator light LA ₃Series connection, J _2-5With LA ₄The series connection, again with both parallel connections, one end and CJ ^* _1-3The other end connect, the other end is connected with center line N; Protection button AN ₃With auxiliary relay J _2-1In parallel, one end with stop to protect button AN ₄, auxiliary relay J ₂Series connection successively, AN ₂With J _2-1The other end and CJ ^* _1-2The other end connect, J ₂The other end be connected with center line N; Current transformer LH ₁With the cloudy MOV of pressure-sensitive electricity ₁In parallel, CJ ^* _1-1The other end by current transformer LH ₁Draw the triple line output terminals A; LH ₂With MOV ₂In parallel, CJ ^* _1-2The other end pass through LH ₂Draw triple line output B; LH ₃With MOV ₃In parallel, CJ ^* _1-3The other end pass through LH ₃Draw triple line output C; LH ₂, MOV ₁An end extremely manage D by two ₁, D ₂Be divided into two rectifying circuits, D ₁Cathode terminal and adjustable potentiometer AR ₁, electrochemical capacitor C ₁Contact connect C ₁With R ₂Contact be connected AR with center line N ₁, R ₂Contact and rectifier bridge heap BR ₁Input connect.Equally, LH ₂, MOV ₂An end pass through D ₃, D ₄Be divided into two rectifying circuits, D ₃Cathode terminal and adjustable potentiometer AR ₂, electrochemical capacitor C ₂Contact connect C ₂With R ₃Contact be connected AR with center line N ₂, R ₃Contact and rectifier bridge heap BR ₂Input connect.LH ₃, MOV ₃An end pass through D ₅, D ₆Be divided into two rectifying circuits, D ₅Cathode terminal and adjustable potentiometer AR ₃, C ₃Contact connect C ₃With R ₄Contact be connected AR with center line N ₃, R ₄Contact and rectifier bridge heap BR ₃Input connect.LH ₁With MOV ₁, LH ₂With MOV ₂, LH ₃With MOV ₃The other end be connected with center line N.D ₂, D ₄With D ₆Back in parallel and R ₁Connect, and receive the input of three terminal regulator 7808.Electrochemical capacitor C ₇, resistance R ₁₁, R ₁₂Parallel with one another, the one end is connected with 7808 input, and the other end is connected with the public end of three terminal regulator 7808.The public end of three terminal regulator 7808 also is connected with center line N, electrochemical capacitor C ₈Be connected across between the public end and output of three terminal regulator 7808.The output of three terminal regulator 7808 is piled BR with rectifier bridge respectively ₁, BR ₂And BR ₃Another input connect.Electrochemical capacitor C ₄, resistance R ₈Parallel connection, one end and rectifier bridge heap BR ₁Output connect other end series resistance R ₅After, again with BR ₁Another output connect.R ₈Two ends and photoelectrical coupler OPT ₁Input connect.Electrochemical capacitor C ₅, R ₉Parallel connection, one end and BR ₂Output connect other end series resistance R ₆, again with BR ₂Another output connect R ₉Two ends and photoelectrical coupler OPT ₂Input connect.Electrochemical capacitor C ₆, R ₁₀Parallel connection, one end and BR ₃Output connect other end series resistance R ₇Back and BR ₃Another output connect R ₁₀Two ends and photoelectrical coupler OPT ₃Input connect.The voltage sample circuit of motor supply line; Miniature transformer TRA ₁, TRA ₂, its major loop is received respectively in 220 volts of supply lines.(CJ ^* _1-1, CJ ^* _1-3The other end and center line N between), the secondary loop all is to be made of tapped two windings.TRA ₁The upper end tap of secondary loop, three rectification circuit D in parallel ₉, D ₁₀With D ₁₁, second transformer TRA ₃The upper end tap parallel connection of secondary loop two rectification circuit D ₁₂And D ₁₃Transformer TRA ₁First rectification circuit of upper end tap, by diode D ₉Cathode terminal and electrochemical capacitor C ₉, adjustable potentiometer AR ₄Contact connect resistance R ₁₃, R ₁₄Parallel connection is again with C ₉, AR ₄Series connection mutually, electrochemical capacitor C ₉, R ₁₃, R ₁₄Contact be connected with center line N, pass through AR ₄, R ₁₃, R ₁₄Contact and rectifier bridge heap BR ₄Input connect.Transformer TRA ₁Second rectification circuit D of upper end tap ₁₀With transformer TRA ₂First rectification circuit D of upper end tap ₁₂Parallel connection is connected to an input, the resistance R of three terminal regulator 7824 ₁₇, R ₁₆, electrochemical capacitor C ₁₁Be connected across between the input and public end of three terminal regulator 7824 electrochemical capacitor C respectively ₁₁Be connected across respectively between the output and public end of three terminal regulator 7824, and a fixing voltage will exporting is transported to rectifier bridge heap BR ₄Another input, electrochemical capacitor C ₁₀With resistance R ₁₅Parallel connection, one end and BR ₄Output connect other end series connection adjustable potentiometer AR ₅The back, again with BR ₄Another output connect resistance R ₁₅Two ends and photoelectricity surely close device OPT ₄Input connect.Transformer TRA ₁The 3rd rectification circuit D of upper end tap ₁₁With TRA ₂Second rectification circuit D of upper end tap ₁₃Parallel connection, the input with three terminal regulator 7824 is connected again, electrochemical capacitor C ₁₃, resistance R ₁₈, R ₁₉Be connected across between the input and public end of three terminal regulator 7824 electrochemical capacitor C respectively ₁₄Be connected across between the input and public end of three terminal regulator 7824.Transformer TRA ₁Tapped rectification circuit D ₇With TRA ₂Tapped rectification circuit D ₈In parallel, the input with three terminal regulator 7809 is connected again, electrochemical capacitor C ₁₅, resistance R ₂₁Be connected across between 7809 the input and public end electrochemical capacitor C respectively ₁₆Be connected across between 7809 the output and public end.The public end of three terminal regulator 7824.7824.7809 is connected with center line N.Photoelectrical coupler OPT ₁, OPT ₂, OPT ₃, OPT ₄Output anodal in parallel, and be connected to the output of three terminal regulator 7809.Photoelectrical coupler OPT ₁, OPT ₂, OPT ₃And OPT ₄The negative pole parallel connection, the base stage with triode NPN is connected again.Resistance R ₂₂One end is connected with the base stage of triode NPN, and the other end is connected with center line N.The collector electrode of triode NPN is connected with the output of three terminal regulator, emitter series resistance R ₂₄The back is connected resistance R with the control utmost point of controllable silicon SCR ₂₃, electrochemical capacitor C ₁₈An end be connected with the emitter of NPN respectively, the other end is connected with center line N; Electrochemical capacitor C ₁₈An end be connected with the control utmost point of SCR, the other end is connected with center line N, the negative electrode of SCR is connected with center line N, anode and midget relay MJ ₁, auxiliary relay J _2-3, J _2-2, resistance R ₂₀Link to each other in turn and be connected to the output of three terminal regulator 7824.Auxiliary relay J _2-6, resistance R ₂₅Series connection is again with electrochemical capacitor C ₁₉Parallel connection, one end and J _2-3, J _2-2Contact connect, the other end is connected with center line N.The direct voltage Table V _-, an end and J _2-3, J _2-2Contact connection, the other end be connected with center line N.

Embodiment 2.

As shown in Figure 2, be the multi-functional threephase motor power supply protection of the utility model case (it is applicable to the protection of high voltage and high power electromotor).For high-power threephase motor (such as 3000 volts, 6000 volts threephase motor), use power supply protection case as shown in Figure 2 to be protected effectively as different from Example 1.High-voltage motor is by high-voltage alternating contactor LJ ^* _1-1, LJ ^* _1-2, LJ ^* _1-3Receive on the high voltage source.And three current transformer LH in the motor current amplitude sample circuit ₁, LH ₂, LH ₃, for high-tension current inductor and fit on the high-tension line; Required common 380V/220V voltage passes through TRA by high voltage source ₃, TRA ₄, TRA ₅Step-down is supplied with.

Symbol among the figure:

L ₁、L ₂、L ₃The triple line input

N center line (zero line)

AN _1,2,3,4Start shooting, shut down, protect, stop to protect button

LA _1,2,3,4AC 220V indicator light

J _1,2Auxiliary relay (coil voltage AC220V)

CJ ^* ₁A.C. contactor (coil voltage AC380V)

MJ ₁Midget relay (coil voltage DC24V)

LH _1,2,3Current transformer

LJ ^* ₁The high-voltage alternating contactor

TRA _1,2Small transformers (220V/2 * 12V 0.5A)

BR _1,2,3,4Rectifier bridge heap (220V 1A)

OPT _1,2,3,4Photoelectrical coupler (TLP521-4)

NPN triode (3DG 130C)

SCR controllable silicon (600V 5A)

V _-D.C. voltmeter

7808.7809.7824 three terminal regulator

MOV _1,2,3Piezo-resistance

D _{1,2 ... 13}Rectifier diode

AR _{1,2 ... 5}Adjustable telecommunications device

R _{1,2 ... 25}Metalfilmresistor

C _{1,2 ... 19}Electrolytic capacitor

A.B.C triple line output (connecing threephase motor)

Claims (3)

1; a kind of multi-functional threephase motor power supply protection case; by power input; switch and protection action actuating mechanism; A.C. contactor; motor current amplitude sample circuit; the voltage sample circuit of motor supply line; amplify the voltage power amplifying circuit of sampled signal and partly form in order to the output that connects motor etc.; it is characterized in that: motor current amplitude sample circuit is to be equipped with three rectifier bridges heap and a three terminal regulator circuit constitutes by three current transformers; each current transformer is all used two rectifying circuit rectifications, and the commutated direct current of first rectifying circuit of each current transformer is pressed (D ₁), (D ₃), (D ₅) be transported to rectifier bridge heap (BR separately respectively ₁), (BR ₂), (BR ₃) an input, another of each current transformer rectifying circuit, (D ₂), (D ₄), (D ₆) all be parallel to the input of same three terminal regulator circuit, the voltage of afterwards the some selected direct voltage of its output being made comparisons, be transported to each rectifier bridge heap (BR ₁), (BR ₂), (BR ₃) another input, the output of each rectifier bridge heap all with separately a photoelectrical coupler (OPT ₁), (OPT ₂), (OPT ₃) input link to each other; And the voltage sample circuit of its motor supply line, then by two miniature transformer (TRA ₁), (TRA ₂), rectification circuit, three three terminal regulator circuit, a rectifier bridge heap (BR ₄) and a photoelectrical coupler (OPT ₄) the circuit composition, its two transformer (TRA ₁), (TRA ₂) major loop all receive respectively in 220 volts of supply lines, the secondary loop all is by there being tapped winding to constitute, transformer (TRA ₁) the upper end tap of secondary loop, three rectification circuit (D in parallel ₉), (D ₁₀), (D ₁₁), transformer (TRA ₂) secondary loop upper end tap parallel connection two rectification circuit (D ₁₂), (D ₁₃), and transformer (TRA ₁) rectification circuit (D of secondary loop upper end tap ₉) direct voltage behind the rectification s is transported to rectifier bridge heap (BR ₄) an input, its upper end tap rectification circuit (D ₁₀) and transformer (TRA ₂) upper end tap rectification circuit (D ₁₂) three terminal regulator circuit of back connection in parallel, the direct voltage of a fixed value of output is to rectifier bridge heap (BR ₄) another input voltage as a comparison, the output of this rectifier bridge heap then with photoelectrical coupler (OPT ₄) input link to each other and transformer (TRA ₁) upper end tap rectification circuit (D ₁₁) and transformer (TRA ₂) upper end tap rectification circuit (D ₁₃) second three terminal regulator circuit of back connection in parallel, the definite value direct voltage of output is as auxiliary relay (MJ ₁) and the operating voltage of controllable silicon (SCR), transformer (TRA ₁) and (TRA ₂) rectification circuit (D that connected of secondary loop centre tap ₇), (D ₈) connect the 3rd three terminal regulator circuit after the parallel connection, the definite value direct voltage of output is made four photoelectrical coupler (OPT ₁), (OPT ₂), (OPT ₃), (OPT ₄) output and amplifying circuit in the required operating voltage of triode (NPN).

2, by the described multi-functional power supply protection case of claim 1, it is characterized in that; In motor current amplitude sample circuit, in order to three rectifier bridge heap (BR to be provided ₁), (BR ₂), (BR ₃) the make comparisons same three terminal regulator of voltage of each input, one of each three terminal regulator is waited in desirable (7808), (7805), (7806), (7809), (7812); In motor supply line voltage sample circuit, in order to rectifier bridge heap (BR to be provided ₄) input make comparisons that the three terminal regulator of voltage has been got (7824) and in order to auxiliary relay (MJ to be provided ₁) and controllable silicon (SCR) three terminal regulator of making work voltage be (7824), in order to four photoelectrical coupler (OPT to be provided ₁), (OPT ₂), (OPT ₃), (OPT ₄) three terminal regulator of the required operating voltage of triode (NPN) is (7809) in output and the amplifying circuit.

3, by the described multi-functional power supply protection case of claim 2; for the protection that is connected the motor on the high voltage source; it is characterized in that; common current instrument transformer in the motor current amplitude sample circuit is changed into high-tension current inductor; and be placed on the high-voltage power-line, and between high-tension current inductor and high voltage source input, install the high-voltage alternating contactor.

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