CN2250586Y - Passive overcurrent protection relay - Google Patents

Abstract

A passive over-current protection relay matched with an electromagnetic switch mainly utilizes the induction current of a current transformer as a detection signal and also as a working power supply, a silicon controlled trigger circuit which can quickly react to the extra-large current is added, the delay time can change along with the magnitude of the over-current, the action is quicker when the over-current is larger, the influence of short-time heavy current can be avoided, and the passive over-current protection relay can effectively perform over-current protection on a load by being matched with the electromagnetic switch such as a contactor and the like, and has the advantages of simple circuit, no need of additional power supply, low production cost, wide application range, reliable work, high sensitivity and the like.

Description

Passive type overcurrent protection relay

The utility model is a kind of protective device when abnormal conditions occurring about electric operating mode, belongs to field of emergency protection.

For prevent motor or other electric equipment because of the overload or other reason burnt out; is furnished with protective device mostly to controlling these electromagnetic switch such as electric; wherein effect is preferably the current protection relay; promptly when load current surpasses predetermined value; detect over-current signal by the punching instrument transformer and drive relay cut-out contactor working power, by the power supply of electrical equipment such as contactor cut-out motor it is protected again through amplifier.But these current protectors need other allotment of labor to make power supply, complex structure, and the cost height simultaneously, does not have the quickening measure to especially big current response speed, makes its reliability not high.

The purpose of this utility model is in order to overcome above-mentioned weak point of the prior art, design a kind of simple in structure, cost is low, can QA passive type overcurrent protection relay to especially big overload current.

Technical measures of the present utility model are: when utilizing the current transformer induced current as detection signal again as working power, increased and to have carried out the rapid-action thyristor gating circuit to especially big electric current and get final product, but its circuit is made up of current transformer TA1-TA2, relay J 1 and contact switch JK1 thereof, unidirectional silicon VS1, push-button switch S1-S2, voltmeter PV1, diode D1-D4, voltage stabilizing didoe D5-D6, potentiometer RP1-RP2, resistance R 1-R2, capacitor C 1-C3, binding post A, B, C, D, E and shell; Its annexation is: TA1 connects the C1 two ends again with after D1 connects with RP1 and S1 parallel connection, the RP1 sliding contact connects the end of TA1, TA2 connects the C1 two ends again with after D 2 connects with RP2 and S2 parallel connection, the RP2 sliding contact connects the end of TA2, R1 with connect the C1 two ends after C2 connects, R2 with connect the C1 two ends after C3 connects, J1 with connect the C1 two ends after VS1 connects, R1 controls between the utmost point with VC1 with the tie point of C2 and is connected in series D3 and D5, R2 controls between the utmost point with VC1 with the tie point of C3 and is connected in series D4 and D6, PV1 is attempted by C1 two ends, post D, E is connected with the C1 two ends respectively, three contacts of relay contact switch JK1 respectively with binding post A, B, C connects.

Accompanying drawing is circuit connecting relation figure of the present utility model.

Referring to accompanying drawing, TA1 and TA2 are the small current instrument transformers among the figure, J1 is with the small-sized DC relay of voltages such as 6V or 9V or 12V, VS1 is the one-way SCR of common model, PV1 is small-sized voltmeter, D5 selects the voltage stabilizing didoe of about 10V for use, D6 selects for use the voltage stabilizing value to be higher than the voltage stabilizing didoe of D5, and the capacity of the Capacity Ratio C2 of C3 is little, and its annexation is identical with technical measures, in order to make RP1 and RP2 can use small-power current potential device, can be at diode D7 of TA1 two ends parallel connection or resistance, a diode D8 in parallel or resistance at the TA2 two ends, in addition, can be in sustained diode 9 of J1 two ends parallel connection, S1 and S2 can use a bidirectional switch.During use, the load main line is got two arbitrarily and is passed from the aperture of TA1 and TA2 respectively, to load minimum can wear several circles more, an other main line can directly pass between two instrument transformers, binding post A, B, C is connected with the circuit of the magnet exciting coil of electromagnetic switch such as contactor, post D, E is connected with one group of normally-closed contact of contactor, can be connected on the normally-closed contact of afterbody contactor for the multistage starting circuit more than the secondary, connect S1 more respectively, S2, adjust RP1, RP2, make the PV1 indicated value a little less than the regular event value, promptly during operate as normal, this relay is failure to actuate; Moment also is failure to actuate by short circuit because of D, E starting shooting; After the start, electric current overrate and after time-delay, C2 are elevated to and make D5 and D3 by by becoming conducting, make VS1 by by becoming conducting, the J1 adhesive, and the JK1 action makes the contactor action and cuts off load power source; If overcurrent is very big, the then very fast rising of C3 voltage makes VS1 conducting J1 action cut off load power source by D6 and D4, and load is protected immediately.

The utlity model has circuit simple, need not other stand-by power source, production cost low, use model Enclose the advantages such as wide, reliable operation, sensitivity height, its delay time can be with the size of inflow-rate of water turbine Change, when inflow-rate of water turbine is more big action more rapid, can avoid again in short-term big the influence of peak current, and connect The electromagnetic switch such as tentaculum cooperate can effectively carry out overcurrent protection to load.

Claims (3)

1, a kind of passive type overcurrent protection relay, but it is characterized in that forming by current transformer TA1-TA2, relay J 1 and contact switch JK1 thereof, unidirectional silicon VS1, push-button switch S1-S2, voltmeter PV1, diode D1-D4, voltage stabilizing didoe D5 one D6, potentiometer RP1-RP2, resistance R 1-R2, capacitor C 1-C3, binding post A, B, C, D, E and shell; Its annexation is: TA1 connects the C1 two ends again with after D1 connects with RP1 and S1 parallel connection, the RP1 sliding contact connects the end of TA1, TA2 connects the C1 two ends again with after D2 connects with RP2 and S2 parallel connection, the RP2 sliding contact connects the end of TA2, R1 with connect the C1 two ends after C2 connects, R2 with connect the C1 two ends after C3 connects, J1 with connect the C1 two ends after VS1 connects, R1 controls between the utmost point with VC1 with the tie point of C2 and is connected in series D3 and D5, R2 controls between the utmost point with VC1 with the tie point of C3 and is connected in series D4 and D6, PV1 is attempted by C1 two ends, post D, E is connected with the C1 two ends respectively, three contacts of relay contact switch JK1 respectively with binding post A, B, C connects.

2, passive type overcurrent protection relay as claimed in claim 1 is characterized in that a TA1 two ends diode in parallel or resistance, a TA2 two ends diode in parallel or resistance, and the J1 two ends also connect a diode.

3, passive type overcurrent protection relay as claimed in claim 1 or 2 is characterized in that D6 selects for use the voltage stabilizing value to be higher than the voltage stabilizing didoe of D5, and the capacity of the Capacity Ratio C2 of C3 is little.