Kirloskar AVR KAVR-1 Circuit Diagram

 

The above diagram shown connection of Kirloskar AVR model KAVR-1. This type of AVR is used in some brush-less alternators manufactured by Kirloskar Electric Company Ltd. This is a single phase sensing AVR. Sensing voltage and working voltage are taken from the main armature (output supply) of the alternator. This is not recommended for unbalanced load. As the AVR is is sensing only the voltage of one phase regulation will not be proper for unbalanced load. Most of the AVR are two phase sensing were as there are some three phase sensing AVR also available. This AVR was used in smaller alternators. Now it is replaced with KAVR-2 which is two phase sensing. This AVR has 3 multy tern potentiometers that are used to adjust the output voltage (P1) Under frequency cut-off (frequency roll off) (P2) and Voltage Stability (P3)

By Adjusting P1 clockwise we can increase the output voltage and counterclockwise adjustment of P1 will decrease the output voltage. 

AVR is supposed to maintain the output voltage with in the limit (for brush-less alternators it is 1% from full load to no-load) at 3% variation in frequency. If engine speed goes bellow 1440rpm (i.e. 48Hz) AVR will stop functioning and will reduce the output voltage. This is done to protect the exciter field, exciter armature and main field windings. At low speed the magnetic flux required to maintain the output voltage will be more and for that more current is required to flow through these windings. It will also reduce the alternator efficiency. Normally FRO (P2) is set at factory and need not be to disturbed.

Voltage Stability Pot (P3) is used to stabilize the output voltage in case there  is a fluctuation of voltage at no-load. On-load fluctuation can be of many reasons like fluctuating prime mover, fluctuating load, high percentage of non-linear load. STAB (P3) is also factory set and need not be disturbed at site.