CN2251214Y - Electronic protector for cage motor - Google Patents

Abstract

The utility model is composed of a bridge eliminator supply and a unit electronic switching circuit. A thermistor is arranged on a motor winding to directly reflect temperature changes, the on-state or cut-off of a transistor is controlled, and an electromotor is protected. The utility model has the characteristics of simple structure, convenient installation, rapid temperature rise, effective and reliable electromotor protection, etc. and can be widely used on the electromotors with various volumes without adjustment.

Description

The squirrel-cage motor electronic protector

The utility model relates to electronic technology, and it is when being used for motor windings and overstepping the extreme limit temperature, is subjected to a kind of squirrel-cage motor electronic protector of electronic protector control.

Development along with modern production; motor is used widely; in use; it should be noted that in phase shortage; stall; overload; under-voltage; ventilation and heat or extraneous thermal source cause electromotor winding temperature to overstep the extreme limit to be burnt; force motor to stop operating; therefore require when above-mentioned situation occurs; can effectively control motor work; avoid motor to burn out, in the prior art, as the patent disclosure of patent No. 92219503.X a kind of " the motor over-temperature protector "; it is a power supply degree depressor; rectification two power pipes; electric capacity; resistance; thermistor; elements such as triode constitute, and complex structure uses element many; but can only be in 80 ℃ of following scopes; and be suitable under the single-phase situation, play a protective role, so the scope of application is very narrow.

The purpose of this utility model is to provide a kind of cost low, applied widely, reliable squirrel-cage motor electronic protector.

Above-mentioned purpose of the present utility model is to realize by such structure, is made of its transistor BG bridge rectification power, unit electronic switching circuit ₁, BG ₂Emitter e be connected to power cathode, resistance R ₄Meet transistor BG ₁Base stage b and positive source, resistance R ₇Meet positive source and transistor BG ₁Collector electrode c, BG ₂The tie point of base stage b on, electromagnetic relay J and capacitor C ₂After the parallel connection, again with the positive pole and the transistor BG of power supply ₂Collector electrode c connect thermistor R ₁Meet transistor BG ₁Base stage b and power cathode, constitute unit electronic switch part.

The utility model operation principle is as follows; Thermistor R ₁Select MF-13 type 22K ± 1% 1/4W, in the time of 115 ± 5 ℃, thermistor R ₁Resistance is that 2K forces transistor BG ₁By the working point, determine resistance R ₄Resistance is because transistor BG ₁Be BG ₂Base stage b biasing resistance, so when motor temperature raises, thermistor R ₁When resistance is 2K, transistor BG ₁End BG ₂Conducting at once, the electromagnetic relay J adhesive of switch on, normally-closed contact cut-out ac contactor coil power supply, motor quits work; When the motor working temperature descends below 120 ℃ thermistor R ₁Value is during greater than 2K, transistor BG ₁Conducting, BG ₂End, electromagnetic relay J outage quits work, and not adhesive makes motor obtain the normal power supply running.Capacitor C ₂Be when supply voltage is on the low side, C ₂Discharge makes transistor BG ₂The adhesive of reliable conducting and electromagnetic relay J.

The utility model said structure can further specify by accompanying drawing.

Accompanying drawing is that the utility model is its circuit theory diagrams.

Among the figure: 1-bridge rectification power, 2-1 facies unit electronic switching circuit

3,4-in addition two facies unit electronic switching circuits

The utility model is made up of bridge rectification power 1, unit electronic switching circuit 1,2,3, its power transformer B ₁, four diode D ₁, D ₂, D ₃, D ₄And capacitor C ₁Constitute bridge rectification power 1,12V is provided DC power supply; Transistor BG ₁, BG ₂, thermistor R ₁, resistance R ₄, R ₇, capacitor C ₂With electromagnetic relay J, constitute 1 unit electronic switching circuit, same structure is formed other two facies unit electronic switching circuits 3,4.

Thermistor R ₁, R ₂, R ₃Become the Y type to link, tie up respectively on three phase windings, and fix with insulating varnish with white cotton tape.

The utility model compared with prior art has simple, the installation side of circuit structure Just, directly reaction temperature changes on winding, and quick heating can be effectively, reliably Control motor because of excess Temperature, and burn out possibility; Wide accommodation need not transferred The whole first-class advantage of motor that is used in various capacity. Can be widely used as all kinds of motor Protective device.

Claims (2)

1. a squirrel cage motor electronic protector is made up of bridge rectification power, unit electronic switching circuit, it is characterized in that the unit electronic switching circuit, transistor BG ₁, BG ₂Expelling plate e connect power cathode, resistance R ₄Meet transistor BG ₁Base stage b and positive source, resistance R ₇Meet positive source and transistor BG ₁Collector electrode c, BG ₂On the tie point of base stage b, electromagnetic relay J and capacitor C ₂After the parallel connection, again with the positive pole and the transistor BG of power supply ₂Connect thermistor R with collector electrode c ₁Meet transistor BG ₁Base stage b and power cathode.

2. squirrel-cage motor electronic protector according to claim 1 is characterized in that thermistor R ₁, R ₂, R ₃Become the Y type to link, tie up respectively on three phase windings, and fix with insulating varnish with white cotton tape.