The S1 Series of 5-kV and 10-kV insulation resistance testers are designed specifically to assist the user with the testing and maintenance of high voltage equipment. Each instrument's control panel is designed in a landscape style which is more familiar and user friendly. CAT IV 600 V safety rating allows for safe use in the widest range of applications. The instruments drive 5 mA of short circuit current which allows for faster charging and testing of large capacitive and inductive loads. The measurement ranges have been increased significantly for both units. The S1-554/2 measurement range has been expanded to 15 T Ohms. The S1-1054/2 offer an increased measurement range to 35 T Ohms. The S1-554/2 offers variable test voltages of 50V to 1kV in 10 V steps and 1kV to 5kV in 25V steps. The S1-1054/2 offers 50V to 1kV in 10 V step and, 1kV to 10kV in 25 V steps. A large, easy-to-read backlit LCD makes them equally suitable for use in both bright sunlight and poorly lit environments. Information displayed includes resistance, voltage, leakage current, capacitance, battery status and time constant. In addition, the elapsed time is displayed constantly, removing the need for separate timers. They also allow up to 3 timed measurement positions to be set, which simplifies DAR testing.