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Practical Over / Under voltage Cut-Out circuit

2017-08-06 19:36  
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This article is to explain in practical / low voltage circuit breaker circuits. The circuit is simple but effective. For your more thorough grasp of this principle, we suggest that you can know more about some of the important components of the circuit, such as: 1N4007 . It uses the comparator in the timer circuit 555. Providing a power supply circuit from a different angle, the relay and the control circuit operation to achieve reliability. Comparator 2 control circuit utilizes Although Comparator 1 output (connected to the reset pin R) is kept low through shorting pin 5 and 6 555 IC. Positive input pin of the comparator 2 is 1/3 of Vcc voltage. So long as the negative input pin 2 is more than 1/3 Vcc is not positive, the comparator 2 output is high, the internal flip-flop is set, ie its Q output (pin 3) is high. Pin 7 is also in a high impedance state, causing the connecting pin 7 is thus lost. Output (at pin 3) Reverse (lower) when pin 2 is taken more positive than 1/3 Vcc. Meanwhile pin 7 down (ask ouptput * Internal flip - failure is high) and the LED connection pin 7 is lit. Two timers (IC1 and IC2) is configured to function in the same fashion. Preset VR1 is adjusted to a low voltage (say 160 volts) circuit breakers through observation, LED1 just lights up when the power supply voltage is slightly higher than the 160 v AC. In this setup, the output at pin 3 IC1 low and transistor T1 is in an off state. Results Reset * Pin 4 IC2 is held high, because it is connected to Vcc through a 100 kohm resistor R4. Preset VR2 is adjusted to over-voltage (say 270 volts AC), just by observing LED2 breaker off when the supply voltage is slightly lower than the 270 v AC. * With the reset pin 4 IC2 is high, the output pin 3 is also high. Thus transistor T2 and energises RL1 for delivery, connected load, power supply via N / O contacts. This is the case as long as the supply voltage exceeds 160 v AC but less than 270 v AC. When the supply voltage exceeds 270 v AC, it will cause the output pin 3 of IC2 to go low and off transistor T2 and disconnect relay RL1, although Reset * Pin 4 is also high. When the supply voltage is lower than 160 v AC, IC1's pin 3 higher, LED1 extinguished. High output at pin 3 results in conduction of transistor T1. Results collector transistor T1 as Reset * Pin 4 IC2 is pulled low. Therefore, the output of IC2 lower and transistor T2 does not apply. Thus relay RL1 is suppressed, resulting in load disconnect supply. When the supply voltage has exceeded 160 v AC (but less than 270 v AC) relay energises again connected load. 

Self switching Power Supply


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