The LTC135 load tap changer testing power supply is an accessory for circuit breaker analysers to test load tap changers where they deliver test currents for the measurements. It's is designed to be used with the following Megger instruments: the EGIL, the TM1600/MA61, the TM1700 series, and the TM1800.
Together with the circuit breaker analyser (CBA) the LTC135 becomes a a test setup for performing dynamic measurements on load tap changers. The unit can also be used for winding resistance measurements and other applications where a constant DC current test signal is required. It is a power supply designed for DC current testing of inductive loads with provisions for discharging the transformer winding when the test is finalised.
The load tap changer is the only moving part connected to the transformer windings. Taking a transformer off the system to investigate an internal problem with a tap changer is an expensive exercise, therefore it is in every utility’s interest to carry out condition assessments of their tap changers to help detect developing faults at an early stage.