• Winding resistance measurement
• Dynamic resistance measurement (DRM)
• Switch sequence timing
• Transition resistor measurement

LTC135 is an accessory for circuit breaker analysers to test load tap changers where it delivers test currents for the measurements.

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.

LTC135 is designed to be used together with the following Megger instruments:

EGIL TM1600/MA61 TM1700 series TM1800

Together with the circuit-breaker analyzer (CBA) it 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 requested. 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.