CN2279726Y - Time-delay thermal protector for electric machine - Google Patents

Abstract

The utility model relates to a time-delay thermal protector for electric machines of overload protectors of electric motors and electric generators, which can solve the problems of the fever and burnout of the electric machine caused by poor heat radiation within rated current and the power cut due to under voltage and overload that affects production when the temperature is low. The utility model is characterized in that the inner part of a protector (2) is provided with a bimetallic strip (4), a normally closed switch (5) and a normally open switch (6), wherein, the bimetallic strip (4) integrates with the housing of the electric machine (1) through a heat transmission sheet (3); the normally closed switch (5) and the normally open switch (6) are connected in a primary circuit or a secondary circuit through a connecting wire (9). The utility model can control the actual operating temperature of electric machines and has a time-delay function for under voltage and overload.

Description

Motor time-delay thermal protector

The utility model relates to the overload protection arrangement of motor, generator.

The protection of existing motor, generator all is to use thermal relay or fuse, protects by the way of restriction electric current, and often in rated current, motor, generator are not smooth because of heat radiation, and ambient temperature is high and burn out, and causes to stop production and economic loss; On the contrary in short-term under-voltage or the overload, motor can't generate heat when burning out, but cutting off the electricity supply influences ordinary production.

The purpose of this utility model is to provide a kind of actual work temperature decision according to motor, generator whether to cut off motor power, to the motor time-delay thermal protector under-voltage, that overload has delay function.

The technical solution of the utility model: bimetal leaf and motor housing are fused with a heat transfer sheet, above bimetal leaf, adorn a normally closed switch and a normal open switch, and be connected in the control circuit (secondary line or a circuit) of motor, generator with lead respectively and in the control circuit of warning device.When motor, generator adstante febre, heat transfer sheet is passed to bimetal leaf with the heat of motor housing, and the temperature of bimetal leaf and motor housing temperature rise synchronously.During near critical value, the bimetal leaf heated bending makes the normal open switch action at motor temperature, the starting warning device, when motor temperature surpasses the safety margins value, the bimetal leaf heated bending makes the normally closed switch action, cut off main circuit (motor power), thereby the temperature of having controlled motor rises no longer.Motor is just under-voltage, when overload, and normal open switch and normally closed switch are failure to actuate, and has only the motor temperature of delaying time inborn ability work of not moving near critical value and when surpassing the safety margins value.

Advantage of the present utility model is directly to control the actual work temperature of motor, generator, and is not subjected to current affects.Under-voltage when long, overload or heat radiation freely do not cause motor, generator heating when (surpassing safety value), all can pre-alarm and cut off main circuit, and avoid motor to burn out.When motor temperature during the end of than, under-voltage in short-term, overload then can not cut off main circuit, keeps ordinary production.Motor can't start when the temperature value of overstepping the extreme limit, and only drops in the limiting value in temperature, just can start.Motor time-delay thermal protector volume is little, and profile has only 30 * 40 * 60mm, and the structure that need not change motor just can be installed.Enforcement of the present utility model can prolong useful life of motor greatly, reduces loss, enhances productivity.

Describe the mode of the present utility model that realizes in detail below in conjunction with accompanying drawing.

Accompanying drawing is the cutaway view of the utility model electric heating time-delay thermal protector.The numeral of marking is represented respectively among the figure: 1, motor (motor, generator) shell; 2, motor time-delay thermal protector; 3, heat transfer sheet; 4, bimetal leaf; 5, normally closed switch; 6, normal open switch; 7, contact supporting; 8, insulation casing; 9, lead.

Motor time-delay thermal protector (2) has an insulation casing (8); normally closed switch (5) and normal open switch (6) are equipped with in insulation casing (8) lining; a bimetal leaf (4) is arranged below it, and (the industrial characteristics of bimetal leaf are to be heated the back to the passive layer bending; degree of crook becomes big with the rising of temperature); bimetal leaf (4) left end is fixed on the insulation casing (8), and joins together by heat transfer sheet (3) and motor housing (1).When motor does not freely cause adstante febre because of under-voltage, overload or heat radiation, heat transfer sheet (3) is passed to bimetal leaf (4) with the heat of motor housing (1), the temperature and the motor temperature of bimetal leaf (4) are risen synchronously, when the motor feels hot temperature during near critical value, bimetal leaf (4) heated bending promotes contact supporting (7), make normal open switch (6) action, normal open switch (6) is connected in the control circuit of warning device by lead (9), thus the starting warning device.If reason that people's this moment can find in time that the motor feels hot, and get rid of fault, then motor temperature returns to normal value gradually, and bimetal leaf (4) temperature descends and flattens directly, and normal open switch (6) is got back to non-action state, alarm release; If reason that people can not find in time that the motor feels hot, fix a breakdown, motor continues heating, temperature surpasses the safety margins value, bimetal leaf (4) makes normally closed switch (5) action again, normally closed switch (5) is connected in the control circuit of motor by lead (9), thereby cuts off main circuit (motor power), realizes the control to motor temperature.After the motor cooling, it is straight that bimetal leaf (4) recovers, and normally closed switch (5) and normal open switch (6) are got back to non-action state, and motor just can be reset.

Motor is just under-voltage, when overload, temperature does not reach critical value, normal open switch (6), normally closed switch (5) are failure to actuate, have only when motor temperature reaches critical value respectively and surpasses the safety margins value, the inborn ability work of not moving, starting warning device and cut-out main circuit reach time-delay purpose under-voltage, overload.

To large-scale three phase electric machine protection, protector is connected in the secondary line; To small-sized monophase machine, protector can be connected in the secondary line, also can be connected in circuit.

Claims (2)

1, the motor time-delay thermal protector that is used for motor, generator overload protection; this protector (2) is contained on the motor housing (1); it is characterized in that there are bimetal leaf (4), normally closed switch (5) and normal open switch (6) in protector (2) lining; bimetal leaf (4) joins together by heat transfer sheet (3) and motor housing (1), and normally closed switch (5) and normal open switch (6) are connected in circuit or the secondary line by lead (9).

2, motor time-delay thermal protector according to claim 1 is characterized in that normally closed switch (5), normal open switch (6) in insulation casing (8), and normal open switch (6) moves in normally closed switch (5) in advance.