The Siemens TS-31 is used to test the operation of the fault protection functions of the Type SB Electronic Trip Unit. It has been designed to be user friendly. The user is prompted by the TS-31, in a step-by-step format, as to the required input information and test instruction. The test results are visually displayed to the user. The TS-31 is available in a portable suitcase style test set that is suitable for testing solid state electronics.