CN2159078Y - Protector for fuse loose-phase and leakage of electric motor - Google Patents

Abstract

The utility model provides a protector for fuse loose-phase and leakage of electric motors, which relates to a protective device for motors. The utility model is characterized in that one end of a fuse device is connected with a zero line, and the other end is connected with the casing of the motor; a control circuit is composed of a power-off normally-closed contact of the leakage protector, a normally-closed contact of an electrothermal relay, an alternating current contactor coil curl, a start button, a stop button, and an auxiliary normally open contact of the alternating current contactor; an A phase and a C phase are respectively provided with a fuse. The utility model has the advantage of favorable security performance, simple structure, low cost, no electric energy loss, and non electrified casing, which can be used for medium and small-sized motors.

Description

Protector for fuse loose-phase and leakage of electric motor

The utility model relates to the protective device of motor, the phase failure of specifically a kind of motor fuse and earth leakage protective device.

As everyone knows; the protective device of existing medium and small motor is made up of bakelite knife switch, fuse, A.C. contactor, thermal relay, and wherein fuse plays that short-circuit protection effect, A.C. contactor play under-voltage, o-volt protection effect, thermal relay plays overload protective function.But because of the service behaviour instability of thermal relay, motor is in operation, if when B phase fuse disconnects owing to short circuit or mechanical reason, under the malfunctioning situation of thermal relay, will cause the operation of motor phase shortage and burns the motor stator winding.It is poor that the motor protective device of this structure has protective value, easily burns motor windings and the deficiency of the normal electricity of motor casing occurs.

The purpose of this utility model provides with regard to being to overcome the weak point of above-mentioned technology that a kind of performance of ensuring public security is good, simple in structure, cost is low, the phase failure of motor fuse and the earth leakage protective device of no electric energy loss and inorganic shell electrification phenomenon.

For achieving the above object; fuse equipment one end of the fuse phase failure and earth leakage protective device that is characterised in that of the present utility model is connected with zero line; the other end is connected with the casing of motor; the outage normally-closed contact of the fuse phase failure and earth leakage protective device is connected with thermal relay normally closed contact, ac contactor coil, stop button, start button and is constituted control loop; two terminals of control loop respectively with A mutually, C is connected mutually, A phase, C are respectively equipped with fuse mutually.The utlity model has security personnel good, simple in structure, with low cost, no electric energy loss of performance and the uncharged advantage of motor casing, can be widely used on the medium and small motor.

Description of drawings:

Accompanying drawing is a kind of circuit theory diagrams of the present utility model, also is the circuit diagram of a kind of embodiment.

Mark in the accompanying drawing is: bakelite knife switch 1, fuse 2,3, thermal relay thermal element 4,5, A.C. contactor main contacts 6, motor 7, the fuse phase failure and earth leakage protective device fuse equipment 8, start button 9, stop the auxiliary normally opened contact 14 of knob 10, ac contactor coil 11, thermal relay normally closed contact 12, the fuse phase failure and earth leakage protective device phase failure normally-closed contact 13, A.C. contactor.

Embodiment: embodiment of the present utility model is described further below in conjunction with accompanying drawing: as shown in the figure, the knife switch 1 of motor major loop is the master switch of control motor A, B, C three phase mains, and A phase, C are respectively equipped with fuse 2,3 mutually.With thermal relay thermal element 4,5; fuse equipment 8 one ends that A, B, C three-phase are connected to A.C. contactor main contact 6, the fuse phase failure and earth leakage protective device respectively are connected with zero line; the other end is connected with casing; A phase, the alternate control loop that is provided with of C; control loop by start button 9, stop knob 10, ac contactor coil 11, the auxiliary normally opened contact 14 of thermal relay normally closed contact 12, the fuse phase failure and earth leakage protective device normally-closed contact 13, A.C. contactor constitutes.During work, the knife switch 1 that closes is pressed start button 9, and control loop has electric current to pass through, and coil 11 produces electromagnetic attraction, makes A.C. contactor main contacts 6, auxiliary normally opened contact 14 closures, motor 7 energising runnings.When stopping, pressing and stop knob 10, the control loop no current passes through, coil 11 dead electricity, and A.C. contactor main contacts 6, auxiliary contact 14 disconnect, motor 7 outage stalls.Motor is in operation process, if A, B, when any two-phase of C three-phase is short-circuited, fuse 2 or 3 will fuse, and the control loop is passed through because of no current, and A.C. contactor main contacts 6 disconnects, motor outage stall.If B phase winding insulation breakdown and when producing ground connection, the fuse phase failure and 8 actions of earth leakage protective fuse equipment; the fuse phase failure normally-closed contact 13 of control loop disconnects; ac contactor coil 11 dead electricity, A.C. contactor main contacts 6 disconnects, motor 7 outages, thereby has played protective effect.

Claims (1)

1; the phase failure of a kind of motor fuse and earth leakage protective device; be provided with the bakelite knife switch; fuse; thermal relay; A.C. contactor; start button; stopping knob forming; fuse equipment one end that it is characterized in that the fuse phase failure and earth leakage protective device is connected with zero line; the other end is connected with motor casing; the outage normally-closed contact and the thermal relay normally closed contact of the fuse phase failure and earth leakage protective device; ac contactor coil; start button; stop the knob series connection and constitute control loop; two terminals of control circuit respectively with A mutually; C is connected mutually, the A phase; C is respectively equipped with fuse mutually.