Automatic voltage stabilizer does not require manual intervention. Relay switches are used which change autotransformer connections. Output voltage adjustment is automatic.
The essential parts of a basic automatic voltage stabilizer are
1. Autotransformer
2. Relay switches
3. Relay driver circuit
4. Control circuit
5. Low voltage power supply
6. Accessories
The auto transformer is similar to that of a manual voltage stabilizer. Several relay switches are used both to connect input voltage and to take output. Transistors and ICs are used in relay driver circuit and control circuit. Step down transformer connected to the input and output produces low voltage usually 18 volt or 12 volt. This low voltage is rectified to get DC voltage which supplies power to relay driver circuit and control circuit. When input voltage changes, the control circuit generate signal for the relay drive circuit. The input voltage may be anything between say 140 volt and 280 volt. Relay driver circuits turns relays on and off connecting input and output to appropriate autotransformer tappings in such a way that output voltage is nearly 220 volt usually anything between 220 to 230. If the input voltage is too low or two high the output is automatically cut off. Accessories include main switch, fuse, on off indicator, voltmeter with selector switch for displaying input or output voltage. Automatic voltage stabilizer provides better protection compared to manual voltage stabilizer. Output voltage adjustment is in steps and not continuous. Common problem include defects in control circuit and relay driving circuit. |