Project Report On Over-Under Voltage Cut-Off With On-Time Delay: Here is a cheap auto cut-off circuit, which is manufactured using discrete transistors and other components. It can be used to cause cargo, such as refrigerator, TV, VCR, and unwanted on-line and low voltage and power fluctuations to be protected by a sudden failure / resumption of power supply source. This circuit can be used directly as a separate circuit from the mains and the load or between existing stabilizer automatically / manually and load to be inserted.
The on-delay circuit not only protects the load from over voltages, but also by the rapid transition (off and on) effect of over / under-voltage relay, in case the supply voltage starts fluctuating in the vicinity of under-or over-voltage preset points. If electricity cut off by default (over or under voltage) limits, the relay / load immediately and it is only when the supply voltage within the preset limits for a period equal to the on time delay switched on. Refrigerators for the delay was for about 2 minutes each preset with the supercharged engine, often to protect an “on” and “off.
In this circuit the on-time and off-time delay depends on charging and discharging time of capacitor C1. Here the discharge time of capacitors C1 is quite less to suit our requirement. We want that on switching ‘off ’ of the supply to the load, the circuit should immediately be ready to provide the required on-time delay when A.C. mains resumes after a brief interrupted for a short period due to over-/under voltage cut-off operation. This circuit is also useful against frequent power supply interruption resulting from loose electrical connections; be it at the pole or switch or relay contact, or due to any other reason.
Conclusion:
The over/under voltage cut-off with ON-Time delay provides various types of protection 1) Over-voltage protection.2) Under-voltage protection.3) Protection against transients.4) Protection to load from frequent turning ON & OFF by providing time delay. The over/under voltage cut-off with ON-Time delay is much cheaper than a regulator and provides much more protection against various faults. The minor project helped us in exploring the market and gathering information about the current market trends.
Download ECE & EEE Project Report On Over-Under Voltage Cut-Off With On-Time Delay.
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