ELECTRIC MACHINES

Automatic Voltage Regulator (AVR) is one of the main component of an Alternator. Main functions of AVR is to built-up the rated voltage and maintain the output voltage within the limit at no-load and on-load conditions. There will not be any output or abnormal output when an AVR fails. What are to be checked before replacing an AVR Disconnect the  AVR. Then check all windings of alternator for continuity and insulation resistance. If any defect is found then rectify it. Never replace the AVR if any winding is having a very low IR value or winding is defective. Connect the AVR after rectifying the defect and then start the machine. If there is no output voltage go to step 2. Check the condition of diodes in RRA. If found defective then replace the defective diode of Rotating Rectifier Assembly (RRA). Start the DG Set. If alternator does not develop  voltage go to step 3. Then run the alternator at idle speed without connecting AVR and note the output voltage. The output volta...

Kerala Electrical & Allied Engineering Company Ltd (KEL) is a Public Sector Undertaken company fully owned by government of Kerala. Their main products are Alternators and Transformers. All alternators manufactured by KEL (in collaboration with Leroy Somer, France) are of Brush Less Excitation type. In lower rantings (<100kVA) no electronic regulator (AVR) is required to regulate the output voltage. In this type of alternator the voltage is build up and regulated with compound excitation system. In higher rating compound excitation & electronic voltage regulators are used to regulate the output voltage. This dual regulation gives high reliability. In this type of alternator one advantage is that we can operate the machine even after an AVR failure. With AVR we will get a 2% voltage regulation and in the second mode it will be 5%. The alternator manufacturing division of KEL is situated in Kasaragod district of Kerala. The above picture shows the regulating part of a KEL ...