The Tan -Delta sets is designed in high voltage protection device that protects the instrument & the operator against failure of test object or standard capacitor. It features the complete range of detector test systems built-in battery operated null detector, almost suitable for quick balancing of the instrument. It is used to test wide range of relays in high accuracy. In addition, the Tan- Delta set can feature Interference compensation unit (ICU) to get the correct readings to withstand over surges such as heavy induction in the circuit.