TEST-901 primary current injection test set adopts 32bit ARM chip to control its output process and large capacity of toroidal transformers. It is equipped with LCD display and current meter; it can show primary current value, second current value, CT ratio and the action time of circuit breaker. Packing is used as aluminum alloy body with PC panel. TEST-901 test equipment is mainly applied to CT turn ratio testing in the power system and contact resistance test which need large current. This model current injection test set is ideal for 1. performance and turn-ratio tests of current transformers; 2. primary tests of protective relays; 3. current tests on low-voltage and high-voltage circuit breakers; 4.commissioning tests that require variable currents in the field.