The Siemens PTS 5 Portable Test Set is designed for performing secondary injection testing of the Static Trip III (STIII) overcurrent tripping system utilized on the RL breaker. The system is packaged in a self-contained briefcase and requires 120VAC to operate. The PTS 5 contains a microprocessor controlled constant current source which enables rapid verification of the performance of the STIII. The desired test current may be directly entered with a numeric keypad for ease of test configuration. The self-contained, automatically controlled digital timer allows simple verification of the time-current tripping characteristics. The system also provides a regulated DC voltage to allow functional testing of the tripping actuator.
The incoming power is converted to a filtered and regulated DC bus. From this DC supply, the testing current is generated using a current amplifier regulated by the microprocessor and a precision digital to analog converter. This provides for stable test current even when the incoming line voltage fluctuates. This feature helps to eliminate discrepancies that may occur if a line-derived current source is used for testing. The test current is applied to the current inputs on the STIII, either by a jumper cable for on-breaker testing, or alternatively, the STIII may be connected to a terminal block on the face of the PTS5 for standalone testing. The STIII connection also provides for the trip feedback that stops the clock and the test current automatically.