The Tinsley 5903 Long Haul Submarine Cable Test Set brings the latest technology to the tried and tested DC methods of cable fault location for both repeatered and un-repeatered systems. The more common test procedures which are associated with the location of types of cable fault such as "open circuits" and "shunt faults" are preprogrammed into the instrument. This allows the procedure to be carried out automatically therefore eliminating operator errors and reducing the uncertainty of the predicted fault position. The instrument may be set for a wide range of voltage and current limits making it suitable for use with most submarine communication cable systems. Safety being an important feature, the instrument gives a continuous indication of the state of charge of the cable under test and will automatically disallow current, voltage or polarity changes to be made until any voltage on the cable has fallen to a level which is safe for both the cable and the instrument. To ensure complete operator safety a number of interlocks operate disconnecting all power before access is allowed to the high voltage areas. The setting up of the instrument is via the menu driven touch screen display. This display is also used to indicate the progress of a test procedure during its implementation. The Ethernet interface is designed for high speed full duplex communication between modules. All functions may also be controlled via a computer and data obtained may be stored for future analysis. This interface may also be used to enable two 5903's to be connected to communicate with each other when carrying out double ended tests such as "no loss of current".