The Siemens PTS-4 test set is designed for testing the static overcurrent tripping systems used on the LA and RL line of low voltage poser circuit breakers. It provides a means of testing the magnetic tripping actuator as well as the static trio device. The portable set, using power from an ordinary 120 volt convenience outlet can provide circuit breaker testing equivalent to much more experience and cumbersome primary current testing. The test itself is quite accurate and can be used to calibrate additional pickup and short time delay values on the trip devices if a sufficiently stable 120 volt line is available. The voltage can be anywhere between 105 and 125 volts, but the value should not vary by more than + 1.5% during testing.