In order to increase the performance of the transformer in the enterprise and to ensure that your operation is not de-energized, the status of the transformer oil and the level of insulation must be kept under control. For this reason, oil tests should be carried out at regular intervals (at least once a year) and insulation levels should be measured.
Secondary protection relays protect power transformers against overcurrent, short circuit and earth faults caused by power transmission lines. It performs the protection operation by opening the circuit breaker with the breakdown current received from the medium voltage current transformer. Relays may be damaged due to their working environment and may not signal the trip on failure. Periodic monitoring of the secondary relays that protect the transformer and the line in the Input-Output Cells of the Transformer Protection Cells with Circuit Breaker is required. Over current relays should be tested with a relay tester once a year. If there are wrong and missing connections at the end of the test, they should be corrected. Relay settings are calculated according to transformer and facility power and their suitability is checked.
Medium voltage current transformers reduce the current measured by power transformers by medium voltage to 5 amperes secondary currents. The secondary side transmits the currents to the protection relays. Relays control these currents and detect any faults that may come to the transformer beforehand and disable the transformer.
MV Current Transformers
Incorrect connection of current transformers can cause false trip signals in protection systems. This can unnecessarily cause your facility to be de-energized. Such inaccuracies can be detected in tests to be performed on current transformers.