CN2165560Y

CN2165560Y - Universal motor protector

Info

Publication number: CN2165560Y
Application number: CN 93241311
Authority: CN
Inventors: 李佩平
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-09-29
Filing date: 1993-09-29
Publication date: 1994-05-18
Anticipated expiration: 2003-09-29

Abstract

The utility model relates to a three-phase AC motor protector which is universal for over current and phase interruption. The circuit structure of the utility model is composed of a synchronous power supply circuit, a current detecting circuit, a phase interruption detecting circuit, an over current detecting circuit, a current preset circuit and a latch output circuit. Because the current detecting circuit adopts a miniature current mutual inductor, a latch output circuit is composed of a trigger latch single phase thyristor CR, a photoelectric coupler thyristor SR, a bridge rectifier QL and C[13], R[20]. The current preset circuit is composed of a constant voltage source IC[2], azimuth gating reducing resistors R[22]-R[42] and two decimal button type digital switches which can be displayed and regulated according to 1.0-10.9. Therefore, the utility model has the advantages of small size, low power consumption, strong overpressure resisting ability, wide current regulating and controlling range, etc.

Description

Universal motor protector

The utility model relates to a kind of three-phase alternating-current motor overcurrent, open phase fault universal electric protector.

Traditional motor protection based on the mechanical type thermal relay, utilizes the inner inspection stream bimetal leaf displacement principle that is heated, and promotes the contact break-make, realizes the protection purpose.Its shortcoming is: the mechanical fatigue life-span is short, and it is low to adjust precision, and product needs seriation etc.China's utility application on August 17th, 1988 disclosed a kind of motor phase failure, overcurrent protector; though the design of this device has reached instructions for use, circuit exists that discrete component is many, volume and power consumption greatly, problem such as the electric current modification scope is little, overvoltage crowbar is not comprehensive.

The purpose of this utility model is in order to overcome above-mentioned weak point of the prior art, and provides the motor that a kind of volume is little, the electric current modification scope is wide, precision is high, overvoltage capabilities low in energy consumption, anti-is strong general protector.

The purpose of this utility model is achieved in that its circuit formation comprises that synchronous power supply circuit, current detection circuit, open-phase detection circuit, over-current detection circuit, current preseting circuit, latch circuit output constitute.Synchronous power supply circuit is by R ₁-R ₃, C ₁-C ₃The step-down of series connection current limliting, VR ₁-VR ₃Star is taken over and is pressed protection to constitute, and in the time of motor starting, three phase mains provides dc supply through three-phase bridge rectification to circuit after this circuit step-down, protection.Current detection circuit is 0.35 * 0.5cm by sectional area ², the coiling of EI sections core micro-transformer of current B ₁-B ₃Constitute, the current signal that detects is through load resistance R ₁, R ₈, R ₉After the linearization process, output voltage signal is sent into open-phase detection circuit and over-current detection circuit respectively.Current preseting circuit is by constant-current source IC ₂, the position selects dropping resistor R ₂₂-R ₄₂And two decimal system key number switches formations of pressing 1.0-10.9 demonstration, regulation and control, this circuit output preset current signal is sent into over-current detection circuit.Latch circuit output latchs one-way SCR CR, photoelectrical coupler controllable silicon SR, bridge rectifier QL and C by triggering ₁₃, R ₂₀Constitute, the one-way SCR CR in this circuit is subjected to current detection circuit and open-phase detection circuit output to trigger, latch, and photoelectrical coupler SR latchs output, through QL, C ₁₃, R ₂₀Behind the ac-dc conversion, control bidirectional triode thyristor SCR break-make reaches the protection purpose.

The utility model compared with prior art has the following advantages:

1, synchronous power supply circuit adopts the step-down of capacitance-resistance series system current limliting, and the power taking resistance two-fold advantage that overvoltage capabilities is strong, electric capacity is low in energy consumption is by VR ₁-VR ₃Three varistors of Y-connection remedy capacitor C ₁-C ₃The shortcoming that overvoltage capabilities is weak, (1W can bear moment tens of times of overvoltage impacts to make the three-phase total power consumption.

2, by B ₁-B ₃The current detection circuit volume of forming is little, and specified single power consumption is 50mW, and linear precision can reach ± and 5%.

3, current preseting circuit adopts two digital key switches combinations, can show, adjusting range is 1.0-10.9, and can be according to B ₁-B ₃Parameter transformation, with reading by taking advantage of 0.1, take advantage of 1, taking advantage of any range conversion such as 10, to adapt to the unequally loaded needs.

4, the latch circuit output input has reduced the quiescent dissipation of power circuit with triggering mode work, and the output latch retention performance can adapt to the needs of frequent operation.

The drawing explanation of accompanying drawing:

Fig. 1 is a circuit block diagram of the present utility model.

Fig. 2 is circuit theory diagrams of the present utility model.

Embodiment describes the utility model in detail below in conjunction with (accompanying drawing).

The circuit of present embodiment constitutes to be made up of synchronous power supply circuit, current detection circuit, open-phase detection circuit, over-current detection circuit, current preseting circuit, latch circuit output 6 parts.Synchronous power supply circuit is by R ₁-R ₃, C ₁-C ₃The step-down of series connection current limliting, VR ₁-VR ₃Star is taken over and is pressed protection to constitute; Current detection circuit is 0.35 * 0.5cm by sectional area ², the coiling of EI sections core micro-transformer of current B ₁-B ₃Constitute; Current preseting circuit is by constant-current source IC ₂, the position selects dropping resistor R ₂₂-R ₄₂And two decimal system key number switches of pressing 1.0-10.9 demonstration, regulation and control constitute; Latch circuit output latchs one-way SCR CR, photoelectrical coupler controllable silicon SR, bridge rectifier QL and C by triggering ₁₃, R ₂₀Constitute.In the time of motor starting, three-phase alternating current is respectively by R ₁-R ₃, C ₁-C ₃After the step-down of series connection current limliting, through three-phase bridge rectification, D ₁₁Voltage stabilizing, C ₄, C ₅Offer circuit working after the filtering, VR ₁-VR ₃Piezo-resistance connects with star fashion, and input is connected on R respectively ₁-R ₃With C ₁-C ₃On the dividing point of series connection, during as generation overvoltage or interference overvoltage, electric current is by VR ₁-VR ₃Absorb, and voltage falls at R ₁-R ₃The overvoltage protection purpose is played at two ends.Transformer B ₁-B ₃The isolation of threephase load electric current is detected, through R ₇, R ₈, R ₉After the processing of load resistance linearityization, a route D ₁-D ₃Halfwave rectifier, C ₆-C ₈Filtering, R ₄-R ₆Coupling output waits average voltage to send into open-phase detection circuit A ₁End of oppisite phase, this voltage is higher than in-phase end R ₁₄, R ₁₅The three-phase maximum of dividing potential drop, A ₁Output low level (is established B during as the generation open phase fault ₁The phase failure), C then ₆Electric energy is through R ₁0 discharges, and R ₅, R ₆Equivalent parallel and R ₄, R ₁₀The series connection dividing potential drop makes A ₁End of oppisite phase is an electronegative potential, A ₁The output high level is through D ₈, R ₁₆, C ₉After the anti-interference time-delay, by thresholding diode D ₁₀Trigger the CR conducting.A ₂Be over-current detection circuit, its end of oppisite phase is by precision constant current source IC ₂, pass through resistance R ₂₂-R ₄₂Step-down, K ₁, K ₂Two decimal system push-button digital switch position selected control systems.Behind the motor starting, B ₁-B ₃Detect electric current through D ₄-D ₆Halfwave rectifier gathers, C ₁₀Be converted to linear DC voltage after the filtering, D ₇Play the overvoltage protection effect, R ₁₃, C ₁₁Form the inverse time lag circuit characteristic, make motor when starting and normal operation, A ₂In-phase end is an electronegative potential, A ₂Output low level, during as generation overload or any phase over current fault, C ₁₀Terminal voltage raises, and passes through R ₁₃Make C ₁₁The time-delay current potential raises A ₂End is output as high level, through D for high potential in the same way ₉, R ₁₈, D ₁₀Trigger one-way SCR CR conducting.A ₃Be connected into current amplifier, with IC ₂The simulation electronegative potential buffering back that provides is for comparison circuit A ₁, A ₂Work.The latch circuit output operation principle is: after the operation energising, electric current is through R ₂₁, C ₁₂, D ₁₂Trigger SCR conducting work, and when fault, the CR conducting that is triggered, SR photoelectrical coupler input is by C ₄, C ₅Pass through R ₁₉The current limliting triggering that sparks, reducing the power circuit quiescent dissipation, and SR exports in the one-way SCR mode, in case trigger, can keep conducting, and SCR bidirectional triode thyristor gate trigger voltage is subjected to metrosil D ₁₂Restriction, trigger current are absorbed by SR behind the QL bridge rectifier, C ₁₃, R ₂₀Can make SR when the power supply zero passage, keep conducting, till SCR shutoff, operating mechanism outage.R ₄₄Piezo-resistance is used for the overvoltage protection of SCR, R ₄₃Make C after acting on power cut-off ₁₁Pass through R ₁₃, C ₄₃Discharge reduction, so far circuit is finished whole protection processes.

Claims

1, the general protector of a kind of motor, its circuit formation comprises synchronous power supply circuit, current detection circuit, open-phase detection circuit, over-current detection circuit, current preseting circuit, latch circuit output, it is characterized in that:

A, synchronous power supply circuit are by R ₁-R ₃, C ₁-C ₃The step-down of series connection current limliting, VR ₁-VR ₃Star is taken over and is pressed protection to constitute;

B, current detection circuit are 0.35 * 0.5cm by sectional area ², the coiling of EI sections core micro-transformer of current B ₁-B ₃Constitute;

C, current preseting circuit are by constant-current source IC ₂, the position selects dropping resistor R ₂₂-R ₄₂And two decimal system key number switches of pressing 1.0-10.9 demonstration, regulation and control constitute;

D, latch circuit output latch one-way SCR CR, photoelectrical coupler controllable silicon SR, bridge rectifier QL and C by triggering ₁₃, R ₂₀Constitute.