The SCITS50D Secondary Current Injection Test Set has a maximum rating of 50 A/0,46 kVA and incorporates a timer. It is designed for testing electricity supply protection systems and particularly measuring the operating times of relays involved in them. Current from the main a.c. terminals is completely variable by use of the output control. The output test current is maintained constant and essentially independent of the load impedance; also, its sinusoidal waveform is regulated so that extra filtering is not necessary. Two independently controlled auxiliary outputs, 240 V a.c. and 240 V d.c. are included. These enable directional relays to be fully tested or can be used as a power supply. The large alphanumeric, dot-matrix LCD indicates the test current and voltage from each output and shows the time elapsed when timing relay operation. The test set has microprocessor circuitry permitting automatic operation as well as having full manual control. Three tactile keys situated below the display are used to set test parameters, initiate a test and control the timer. These control keys take on various functions as defined by the software test programme and shown on the display (which can be set to read in English, French, German, Italian or Spanish). Microprocessor control, together with the facility to manually control the equipment, gives the operator the choice of two basic operating modes. Both modes can have a maximum test time specified. The manual mode enables small values of current to be adjusted using a three turn potentiometer, the maximum value of which can be preselected. The programmable modes allow the test current level to be set before the initiation of a test. Within these modes, the test set will automatically measure the forward and/or runback times of the protection system?s relay. (Note that a runback time count must always be terminated manually.) A remote pushbutton can be fitted, which enables the user to control the time counter while closely watching the relay. An RS232 serial data port is provided for sending test results to an external recording device. Fuses, power dissipation and overcurrent detection and a thermal cutout combine to provide enhanced instrument circuit protection. The test set is constructed in a robust case with large carrying handles; for easy transportation, a trolley is available optionally.