Auto Changeover from Generator to Mains Supply

Because of energy crisis Load shedding may be a common problem in several countries.. Sudden power fluctuations, surge and high voltage may spoil sophisticated household appliances like TV, VCR, VCP and music system. This circuit provides protection against these problems and automatically changes the power supply from Generator output to mains supply and also switches off the generator.

Circuit descriptions

This circuit is self explanatory. When lines supply voltage crosses the preset level, Zener diode ZD4 break down and thus transistor T2 conducts, T3 does not conduct, causing the relay to de-energise. Voltage surge at the time of power resumption is protected by the delay circuit around transistor T1.

All the portable petrol and kerosene generators have a connection from CDI. To stop the engine of the generator-set, this connection is to be grounded momentarily (through the switch). This lead is to be connected with the ground through the N/C point of the relay.

Auto Changeover from Generator to Mains Supply Circuit Diagram

Instead of the one transformer, two transformers are used in series to ensure better life of the unit. Value of capacitor C2 can be increased or decreased for the variation of delay time. A negative feedback resistance, R6 (15 K-ohm to 100 k-ohm) can be incorporated between transistor T3 and T4 to overcome the damage that could be caused by voltage fluctuations.

Parts List:

Resistors (all ¼-watt, ± 5% Carbon)

R1 = 10 Ω

R2 = 1 KΩ

R3 = 820 Ω

R4 = 57 KΩ
R5 = 47 Ω

R6 = (15 KΩ to 100 KΩ)

Capacitors

C1 = 100 µF/25V

C2 = 1000 µF/12V

C3 = 100 µF/18V

Semiconductors

T1 = BC147

T2, T3 = SL100

D1, D2 = 1N4001

D3 = 1N4007

ZD1 = 5.6V/400mW

ZD2 = 7.8V/400mW

Miscellaneous

X1, X2 = 230V AC primary to 12 V, 500mA secondary transformers

RL1 = 12V/450 Ω relay

Comments

Digital Fan Regulator Circuit Diagram

This is the project of Digital Fan Regulator Circuit diagram. The circuit presented here can be used to control the speed of fans using induction motor. The speed control is nonlinear, i.e. in steps. The current step number is displayed on a 7-segment display. Speed can be varied over a wide range because the circuit can alter the voltage applied to the fan motor from 130V to 230V RMS in a maximum of seven steps. The triac used in the final stage is fired at different angles to get different voltage outputs by applying short-dura-tion current pulses at its gate. For this pur-pose a UJT relax-ation oscillator is used that outputs sawtooth waveform. This waveform is coupled to the gate of the triac through an optocoupler (MOC3011) that has a triac driver output stage. Pedestal voltage control is used for varying the firing angle of the triac. The power supply for the relaxation oscillator is derived from the rectified mains via 10-kilo-ohm, 10W series dropping/limit-ing...

Using the SG3525 PWM Controller Explanation and Example Circuit Diagram Schematic of Push Pull Converter

PWM is used in all sorts of power control and converter circuits. Some common examples include motor control, DC-DC converters, DC-AC inverters and lamp dimmers. There are numerous PWM controllers available that make the use and application of PWM quite easy. One of the most popular of such controllers is the versatile and ubiquitous SG3525 produced by multiple manufacturers – ST Microelectronics, Fairchild Semiconductors, On Semiconductors, to name a few. SG3525 is used extensively in DC-DC converters, DC-AC inverters, home UPS systems, solar inverters, power supplies, battery chargers and numerous other applications. With proper understanding, you can soon start using SG3525 yourself in such applications or any other application really that demands PWM control. Before going on to the description and application, let’s first take a look at the block diagram and the pin layout. Pins 1 (Inverting Input) and 2 (Non Inverting Input) are the inputs to the on-board error amplifier. If you a...

Automatic Intruder Alarm Circuit Diagram

Description: This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It's designed to be used with the usual types of normally-closed input devices such as - magnetic reed contacts - micro switches - foil tape - and PIRs. But it can be Easily Modified to accept normally-open triggering devices - such as pressure mats. Circuit Diagram Notes: It's easy to use. First check that the building is secure and that the green LED is lit. Then move SW1 to the "set" position. The red LED will light. You now have about 30 seconds to leave the building. When you return and open the door - the Buzzer will sound. You then have about 30 seconds to move SW1 to the "off" position. If you fail to do so - the relay will energize and the Siren will sound. While at least one of the switches in the normally-closed loop remains open - the Siren will continue to sound. However, about 15-minutes aft...

ffd

Search This Blog