CN2081596U

CN2081596U - Electronic thermorelay

Info

Publication number: CN2081596U
Application number: CN 90226974
Authority: CN
Inventors: 李士华
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-12-28
Filing date: 1990-12-28
Publication date: 1991-07-24

Abstract

Disclosed is a miniature electronic thermorelay, which is composed of a thermistor, a protective circuit, a Schmidt trigger circuit, a drive circuit, a relay, a power section, etc. The thermistor is stuck to the coil winding of an electric motor or an electric device by a lead wire. The normal open node of the relay is connected in parallel on the starting button of the electric motor or the electric device control circuit. The main voltage is alternating current voltage of 380V which is taken from the self-closing electric motor or the electric device. The miniature electronic thermorelay can give automatic protection to the insulation materials of the electric motor or the electric device and the insulation materials can not be burnt out. The miniature electronic thermorelay has the function of simulating overheat test running and has advantages of high reliability, wide voltage range, small volume, low cost, etc.

Description

Electronic thermorelay

The utility model belongs to motor or electric prospection technical field.

Existing mechanical type thermal relay can not have been protected unlikely the burning out of insulating material of motor or electrical equipment effectively, even adopt thermistor flush type electronics overheat protector, also exists poor reliability, adapts to narrow, the shortcomings such as volume is big, cost height of voltage range.

The purpose of this utility model just provides a kind of miniature electronic thermal relay; it can protect unlikely the burning out of insulating material of motor or electrical equipment automatically; and have the overheated test-run a machine function of simulation, and the reliability height, adapt to that voltage range is wide, volume is little, low cost and other advantages.

Operation principle of the present utility model is exactly that thermistor is bonded on the coil windings of motor or electrical equipment, and directly sensitive temperature is converted to the signal of telecommunication and imports this thermal relay.When normal temperature, just produce the high level signal, and through Schmidt trigger circuit and drive circuit, what make relay often opens the node closure, and the power supply of connecting motor or electrical equipment normally moves.

If overheating problem takes place or holding wire is short-circuited, during open circuit fault, this thermal relay produces low level signal, and the node of often opening of relay is disconnected, and cuts off the power supply of motor or electrical equipment, unlikely the burning out of insulating material of protection motor or electrical equipment.

Accompanying drawing is an operation principle line map of the present utility model.

Embodiment of the present utility model is illustrated in conjunction with the accompanying drawings.

To take from the 380V alternating voltage of connecting motor or electrical equipment, through current-limiting resistance R ₁With and the decompression capacitor C that connects ₁, bleeder resistance R ₂, R ₃After, again through rectifier bridge D ₁～D ₄, filter capacitor C ₂With voltage-stabiliser tube DW, obtain the 24V direct voltage at the A point.This voltage is through resistance R ₁₅Step-down and capacitor C ₃After the filtering, obtain the 15V direct-current working volts at the B point.And on voltage-stabiliser tube DW the serial connection luminous tube L.

Three switching mode semistors are serially connected, and closely are bonded on motor or the electric apparatus coil winding, are connected to 1,2 two ends of this thermal relay then by lead-in wire.

The 15V direct voltage is through resistance R ₄After meet BG ₁Base stage, or through resistance R ₅Ground connection, BG ₁Collector electrode through resistance R ₆Connect the 15V direct voltage, BG ₁Emitter connect 1 end, between 2 ends and ground and connect normally closed button K, resistance R ₇1 end output be connected to the work of 15V direct voltage, by BG ₂, BG ₃And resistance R ₈～R ₁₃The Schmidt trigger circuit that constitutes, BG ₁, BG ₂Collector electrode output through resistance R ₁₄After meet BG ₄Base stage, BG ₄Grounded emitter, BG ₄Collector electrode through and the diode D that connects ₅, connect the 24V direct voltage after the relay J.Often opening on the start button that node is attempted by motor or electrical apparatus control circuit of relay J.

After the start button of motor or electrical apparatus control circuit is pressed startup, connect the power supply of motor or electrical equipment, keep supplying the 380V alternating voltage also for simultaneously this electronic thermal relay.When motor or electrical equipment under normal temperature during normal operation, thermistor is low-resistance, makes BG ₁, BG ₂End BG ₄Conducting, engage relay J, relay J often open node closure, the start button self-locking energized of motor or electrical apparatus control circuit.Motor or electrical equipment continue normal operation.

When the coil windings temperature fault of motor or electrical equipment was warming up to the thermal endurance class temperature of insulating material, the resistance of thermistor raise unexpected straight line, BG ₂Conducting immediately, BG ₂Current collection is low level very, again through resistance R ₁₄Step-down is added in BG ₄Base stage, BG ₄End, relay J discharges, and the node of often opening of relay J disconnects, and cuts off motor or appliances power source, reaches the unlikely purpose that burns out of insulating material of protection motor or electrical equipment.BG ₂And BG ₃And the Schmidt trigger of resistance formation, be in order to add speed motor outage speed, to be unlikely to when protection, to take place messy phenomenon.

When short trouble appears in connection thermistor signal line, BG ₁Base potential will be higher than emitter current potential, BG ₁Conducting, BG ₁Collector electrode output low level signal, BG ₄End, relay J discharges, and cuts off the electricity supply.

When open circuit fault appears in connection thermistor signal line, BG ₂Base stage be high potential, BG ₂Conducting, BG ₄End, relay J discharges, and cuts off the electricity supply.

Press the normally closed button K of the overheated test-run a machine of simulation, promptly seal in a high value resistor R at signal input part 1,2 two ends ₇, make BG ₂Conducting, BG ₄End, relay J discharges, and cuts off the electricity supply.

Adopt capacitance decompression, saved the transformer copper-steel material, reduced cost again, but wanted series resistance R ₇Could effectively limit because of electric capacity causes destructive surge power supply, guarantee trouble free service.R ₂, R ₃Can discharge capacitor power guarantees safe and reliable.

Adopt parallel connection type voltage-stabiliser tube DW and capacitance decompression combiner circuit to have special broad voltage stabilized range, can reach 120V～480V alternating voltage.Luminous tube L connected with voltage-stabiliser tube DW use the additional function that luminous tube L extinguishes when can obtain to be lower than the 300V alternating voltage, tell person on duty's power supply under-voltage to the flagrant lower limit of motor (for 380V).

Claims

1, a kind of by thermistor, protective circuit, revolve the miniature electronic thermal relay that close special circuits for triggering, drive circuit, relay, power supply etc. are formed, it is characterized in that:

A, 3 switching mode semistors that closely are bonded on motor or the electric apparatus coil winding are serially connected, and are connected to 1,2 two ends of this thermal relay by lead-in wire;

B, will take from the 380V alternating voltage of connecting motor or electrical equipment, through current-limiting resistance R ₁With and the decompression capacitor C that connects ₁, bleeder resistance R ₂, R ₃After, again through rectifier bridge D ₁～D ₄, filter capacitor C ₂With voltage-stabiliser tube DW, obtain the 24V direct voltage at the A point, this voltage is through resistance R ₁₅Step-down and capacitor C ₃After the filtering, obtain the 15V direct-current working volts at the B point;

C, 15V direct voltage are through resistance R ₄After meet BG ₁Base stage, or through resistance R ₅Ground connection, BG ₁Collector electrode through resistance R ₆Connect the 15V direct voltage, BG ₁Emitter connect 1 end, between 2 ends and ground and connect normally closed button K, resistance R ₇, 1 end output be connected to the work of 15V direct voltage, by BG ₂, BG ₃And resistance R ₈～R ₁₃The Schmidt trigger circuit that constitutes, BG ₁, BG ₂Collector electrode output through resistance R ₁₄After meet BG ₄Base stage, BG ₄Grounded emitter, BG ₄Collector electrode through and the diode D that connects ₅, connect the 24V direct voltage after the relay J;

D, often opening on the start button that node is attempted by motor or electrical apparatus control circuit with relay J.

2, electronic thermal relay according to claim 1 is characterized in that: luminous tube L of serial connection on voltage-stabiliser tube DW.

3, electronic thermal relay according to claim 1 and 2 is characterized in that: adapt to voltage range and be 120～～the 480V working volts alternating current.