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Latching Relay

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Principle And Implementation Of Power-off Delay Relay
Nov 29, 2017

Principle and implementation of power-off delay relay

When the time relay coil is energized, the delay contacts act instantaneously, and after the coil is switched off, the contacts are in the state of delayed setting, and when the set delay arrives, the delayed contacts resume to the initial state. Time delay due to the working condition (in delay process without an external power supply) and control in time delay in the process of attracting contact contact (normally open to the on state should keep on state variable; the normally closed contact fault should be in open state, remain disconnected state) transfer particularity (just in contrast with the conventional cm-pss type time relay contact state) to meet the control requirements. The delay time relay is composed of the earliest separation device (low delay precision and short delay time). The delay is completed by the corresponding programmable timing IC or CMOS counting and frequency division. Compared with the delay relay, it has the characteristics of high delay precision and long delay time. In order to meet the long time delay control situation.

Typical circuit

The overall composition including the power-off delay relay off delay relay power supply (step-down rectifier filter) to provide built-in instantaneous power-off delay relay electromagnetic relay and 2 winding latching R reset coil); two power supply (for power after the delay part and the 2 winding latching S set coil); delay part (programmable timing integration or CMOS integration; driving frequency counting);


The power cut delay relay composed of V2 P trench FET, V3, V4 triode and relay as main components is shown in figure 2. As follows: after the end of the work power supply, C1~C5 will complete the charging process according to its circuit (charging time should refer to the time specified by the product).  At the same time, the internal reset coil latching relay R 2 winding electric work (in 4 and 6 switching contacts gridlines from power on to off state, 4 and 8 on the corresponding conversion), an external contact terminal is connected, a delay state).

When the terminal power supply is powered off, the corresponding relay enters the delayed working state. The V2 P channel field-effect tube, with C4 R6 RP2, after discharge, the source voltage of S decreased (in the energized state, because of the small UGS, ID zero, V2 as the deadline, according to the working state) transfer characteristics of corresponding FET (drain current relationship between ID and gate the source voltage between VGS VGS) when the voltage reaches VGS (Th) (open voltage), V2 conduction. With the V2 turn-on, the leakage current ID generates a corresponding voltage drop through the R4, so that the V3 transistor works, eventually leading to V4 also conduction. When the V4 is switched on, the stored energy on the C5 capacitor will make the 2 winding latching relay set on the power line, so that the delayed contact can resume the original state, thus completing the power off delay work.

The delay circuit faults is not easy to set parameters, usually to adjust RP2 (control C4 discharge circuit and RP1 adjustment (V2) to determine the gate voltage, C4, C3) and the capacitance parameters are calculated, and the discrete devices make delay error, adjustment is not easy, now rarely used basic on.

The delay circuit composed of integrated CD4060 is shown in figure 3. The core delay of the circuit is composed of CD4060, and the delay setting is set by the RP1 and the configured C3. The internal 2 winding latching relay adopts DC24V (the relay with higher working voltage, which can reduce the driving current and make the driving part simpler). At the end of the work power supply, V1 triode work, so that the R reset coil pulling work, the internal contacts back to the original state. C2, C4 complete charging work.


When the working power is switched off, the corresponding power delay working state is entered. IC 12 pin generates a level in R3 because of C1 discharge, and the reset pin is cleared by R4 to pin 12. The delay time is started, and the delay time is driven by Q4~Q14 (according to the demand delay time) to drive the V2. After the delay arrives, the oscillation is stopped by VD7. According to the time delay, the C2 capacitor can be correspondingly increased or reduced (the capacity of C2 is increased or decreased in parallel), and the C4 capacitor is used to complete the work of the S set coil.


The characteristics of the line are convenient setting delay, high delay precision and simple product adjustment, and are widely used at present.

  

Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni
Tel:+86-573-84775555
Fax:+86-573-84776699
Phone:+86-13732570078
E-mail:sales9@great-relay.com
       sunny.ni@great-relay.com