Static or Solid State AC Voltage Stabilizer

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Static or Solid State AC Voltage Stabilizer

Block Diagram of Solid State AC Voltage Stabilizer :

Solid state regulator can be of two types :

  1. Tap changing type
  2. Phase control type

The block diagram is as shown in Figure A. The input output voltage waveforms are as shown in Figure B.

Solid State Regulator
Figure A

Input Output Voltage Waveforms for Solid State Regulator
Figure B

Operation of Solid State AC Voltage Stabilizer :

  • Identical to the tap changing regulator circuit discussed in the previous section, this circuit also uses a transformer with tapped primary winding. Instead of using relay contacts now a pair of back to back connected SCRs is used for each tap.
  • The sensing circuit senses the output voltage and selects a particular tap by triggering the corresponding pair of SCRs. e.g. if the voltage is 230 Volts i.e. normal then SCRs 1 or 2 will be triggered to connect point C to the Live point of the input supply.
  • A smooth adjustment in the output voltage is then obtained by automatic adjustment of firing angle “α” of the selected pair of SCRs. Thus the output voltage now can be adjusted in a stepless manner.
  • If the load voltage is low i.e. say below 180 Volts, then SCRs 3 and 4 are selected for conduction. Their firing angle can then be adjusted to further regulate the output voltage.

Waveform of  of Solid State AC Voltage Stabilizer : Figure B.

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