CN2192970Y

CN2192970Y - Protective knife switch for three-phase electric motor

Info

Publication number: CN2192970Y
Application number: CN 94212706
Authority: CN
Inventors: 毛亚强
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-05-27
Filing date: 1994-05-27
Publication date: 1995-03-22
Anticipated expiration: 2004-05-27

Abstract

The utility model relates to a protective knife switch for three-phase electric motor, belonging to the field of the low voltage circuit, and the utility model is a controlling switch which has various protective functions. This designing provides a novel concept that a 'V'-shaped memory alloying-plate and a tripping device are increased in the existing three-phase bakelite knife; when the electric motor brings the burning-out of the fuse wire because of excess load, the V connected with the fuse wire moves to trigger the machinery of the trip so as to cut off the three-phase power supply rapidly. Three V memory alloying-plates can be used to replace the electronic-type protector and the movement actuator of the AC contactor here; meanwhile, a null-sequence mutual-inductor and more than ten electronic components are added, and thus a multifunctional controlling knife switch for the electric motor is formed.

Description

Protective knife switch for three-phase electric motor

The utility model belongs to the low-voltage electrical apparatus field, be a kind of be the control switch that the automatic protective value of multiple function motor is arranged.

At present, known widely used three-phase bakelite disconnecting link mainly is the porcelain base, and three fuses, Third Mate's dynamic/static contact firm banking binding post are with two compositions that separate.Directly control motor with this three-phase disconnecting link, during often because of a certain phase fuse failure, motor is operated in the two-phase running status, and the electric current that flows through motor this moment increases

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Times, very easily burn out motor, if motor is protected, adopt electron type protector and A.C. contactor to form monitoring and automatic power cutoff mechanism at present, its equipment installation cost increases greatly.And the various electron type motor protectors that existing market is sold, because of poor for applicability, heavy current impact causes misoperation again easily during starting, does not often have protective effect, increases the spoilage of motor on the contrary.

The purpose of this utility model provides a kind of novel disconnecting link switch of practicality, control a motor separately with it, after a certain phase factor electric current increases fusing, can cut off the power supply automatically, and it is cheap to keep fuse, has the distinct advantages of anti-heavy current impact of moment; They are two years old, the maintenance electrician can be equipped with suitable insurance according to power of electric motor, has solved the problem of versatility, and they are three years old, a motor only need be joined a disconnecting link switch, promptly has control, transition, phase shortage, short circuit, electric leakage, electric shock, overvoltage, under-voltage eight functions.

The utility model is specifically implemented branch a type and two kinds of specifications of b type.The a type is on the three-phase bakelite disconnecting link basis that everybody knows, change the knife-edge contact and be the face contact, set up simple mechanical tripping device and make auto-power-off device, between release and fuse, put into the V memory alloy element, be used for monitoring the fusing situation of fuse, under the normal condition, utilize the pulling force of fuse that two sheet metals of V are closed up, because of being fixed on one side, another side and release office are left, fuse melting when overcurrent or short circuit, V recovers original form and touches release office, release action, three-phase moving contact from power supply are separately opened because of V at this moment, release can't recover, so close not brake application, run single-phase disconnecting link switch and send and do not power on, have only when changing new fuse and tension and could close a floodgate and send.Wherein release is domestic general electrical equipment mechanical trip mechanism.B type disconnecting link switch is to set up zero-sequence transformer on the basis of a type embodiment, electronic circuit board, piezo-resistance, solenoid.Electric leakage or electric shock appear in external circuit in the base rear cavity in case all be arranged on, zero-sequence transformer is exported an induced voltage signal when leakage current value surpasses regulation, amplify the solenoid that drive is arranged on the release side through the electronic circuit shaping, armature drives the release action and disconnects three phase mains because of linking to each other with release office.The realization of overvoltage is that a piezo-resistance is connected in series any two-phase load end, the above high pressure of 400V occurs on the electric wire when meeting thunderbolt.Piezo-resistance is conducting immediately, the output of zero-sequence transformer voltage signal, and situation is identical with electric leakage.Under-voltage realization is to be monitored automatically by Schmidt circuit, and (such as 320V) not gate output signal when external voltage is reduced to a certain value becomes 1, solenoid action, deenergization immediately by 0.

This electronic circuit board comprises the rectifier bridge D that links to each other with zero-sequence transformer ₁-4, diac D ₅, controlled sulphur SCR, anode are pressed diode D ₆With power supply B, negative electrode is connected power supply C with solenoid (16), control utmost point G and diode D ₅Connect another road NAND gate Y ₁, Y ₂, D ₇, 2CW serial connection, then again with R ₁, R ₂, W ₁, C ₂Connection in series-parallel.

Owing to adopt such scheme, utility model Q type disconnecting link switch is to increase by three V memorial alloy sheets and simple release on the three-phase bakelite disconnecting link basis that everybody knows, the former monitors the flow short-circuit and the phase shortage excessively of motor, the latter carries out action, through improving like this, structure is still very simple, but function increases greatly, no matter that phase fuse melting, all can cut off the electricity supply by action message.Because of not re-using electron type protector and A.C. contactor, cost reduces greatly, and not power consumption itself.I have manufactured experimently a sample, though manufacture craft is coarse, all can accomplish absolutely success.Up to the present, all employings of domestic development motor protection are walked electronics and are protected this road.The utility model provides a kind of simple, reliable and stable again new way, makes the control of motor save complicated electronic circuit and relay, the valuable electrical equipment of A.C. contactor.The whole nation has tens million of motor to be burnt out every year at present, and wherein because of overcurrent, phase shortage, the reason of short circuit accounts for more than 80%, if adopt this utility model, the spoilage of motor is reduced greatly.

The multi-functional disconnecting link switch of b type has overcurrent, phase shortage, short circuit, electric shock, electric leakage, overvoltage, under-voltage eight functions simultaneously, and the control occasion that is specially adapted to humidity, danger, work high above the ground is used.

Below in conjunction with drawings and Examples the utility model is further specified.

Fig. 1 is the utility model a type circuit theory diagrams.

Fig. 2 is the broken section structural map of the utility model a type embodiment.

Fig. 3 is the utility model b type circuit theory diagrams.

Fig. 4 is the broken section structural map of the utility model b type embodiment.

As can see from Figure 1 in a Motor Control circuit, power supply (1) in order,---fixed contact (2);---moving contact (3),---and moving contact one release (5),---fuse (sheet) (10);---motor protector (8),---motor (15).

In the embodiment shown in Figure 2, three phase mains (1) inserts three the fixed contact terminals (2) on the bakelite switch, the moving contact (3) that contacts with the stationary contact women's head-ornaments then, release (5), soft copper lead (4), connect the fuse binding post (9) that can in memory alloy element (8), slide then, and then fuse (10) is connected across between the load wiring terminal (11), at ordinary times, the pulling force of fuse itself makes (8) separate with release office (7), in case stall appears in motor, this moment, electric current continued to raise, current value over insurance scope causes heating elongation or fusing, the memorial alloy sheet restores to the original state and collide (7), touches the release action, cut off the electricity supply.

Fig. 3 circuit diagram and Fig. 1 place inequality is, flexible conductor is passed through a zero-sequence transformer (19)---when the thunderbolt high pressure appears in external circuit, piezo-resistance is instantaneous to be led, or there is the people to get an electric shock and motor makes moist when electric leakage, zero-sequence transformer has signal output immediately, touch the release mechanism action through a circuit shaping---amplification---starting relay of taking a sample, the under-voltage signal in another road is given Schmidt circuit---amplifies---starting relay---release action---deenergization.

Embodiment shown in Figure 4 and Fig. 2 embodiment place inequality are assemblied in electric shock, electric leakage, overvoltage, circuit under-voltage, principle design on the small-print plate and one of zero-sequence transformer is arranged in the cavity of this disconnecting link switch bakelite shell base back, then with thin bakelite plate sealing.The unified design of a type and b type shell is so volume is identical.

The a type has overcurrent, phase shortage, short circuit, controlled function.

The b type has overcurrent, phase shortage, short circuit, control, electric shock, electric leakage, overvoltage, under-voltage function.

Claims

1, a kind of novel threephase motor protection disconnecting link switch, it comprises and is contained in fixed contact (2) moving contact that is linked in sequence in the insulation crust, (3) fuse, A (10) face terminals (11) is characterized in that: described disconnecting link switch comprises that also zero-sequence mutual inductance should (19), piezo-resistance (22) and electronic circuit board (21); This electronic circuit board comprises the rectifier bridge D that links to each other with zero-sequence transformer _1-4Trigger diode D ₅Controllable silicon SCR, anode meet diode D respectively ₆With power supply B, negative electrode is connected power supply C simultaneously with solenoid (16), control utmost point G and diode D ₅Connect another road NAND gate Y ₁, Y ₂, D ₇2CW serial connection, then again with R ₁, R ₂, W ₁, C ₂Connection in series-parallel, piezo-resistance R ₃With resistance R ₄Series connection connects A, B two-phase respectively.

2, switch according to claim 1 is characterized in that insulation crust divides base and loam cake, and base back surface is provided with a cavity, and 2 fixed legs and a button are arranged in the cavity, and insulation crust adopts black or white electric bakelite to make.

3, switch according to claim 1 is characterized in that the fixed copper post of fuse is the square-section, and an end inserts in the middle square hole of " V " shape sheet metal, and keeps 0.1～0.2mm gap, and the other end has the screw of fixing insurance.

4, switch according to claim 1 is characterized in that " V " shape sheet metal is to make of the alloy of the copper of thick 0.2～1.0mm and beryllium, tin, phosphorus or iron and nickel, chromium element.

5, according to claims 1 described switch, it is characterized in that: three-phase zero-sequence transformer, electronic circuit board are arranged in the bakelite base back surface cavity, seal with insulation board then.Wherein solenoid (16) is fixed on the tripping mechanism top, and armature links to each other with release office.

6,, it is characterized in that fuse closes matrix manufacturing with zinc, tin, copper garden shape and two kinds of structures of flat are arranged, and print the fuse of character cut in bas-relief in the above with the watt level typing according to claims 1 described switch.