3388 Compressed Gas Standard Capacitor The compressed gas standard capacitor is an indispensable instrument in every high voltage laboratory and test field where it occupies a wide range of important functions. The compressed gas capacitor is used as capacitance standard in bridge circuits to measure the dielectric dissipation factor tan , the dielectric constant r respectively the capacitance of cables, ducts, insulators, transformer windings and insulates. DESIGN FEATURES The capacitor consists of the following main elements: - high-polished cylindrical electrodes casing serving as pressure vessel, high voltage connection, duct for test electrode and shield, gas inlet valve mental base with shielded plug and ground screw The compressed gas capacitor is filled with sulphur hexafluoride SF6 and under pressure ADVANTAGES Excellent capacitance constancy Changes in atmospheric pressure and humidity without influence on capacitance Small dielectric dissipation factor tan Partial discharge free Possibility to neutralize partial capacitances influencing measurements with voltage regulator 0 Guard electrode 1 High Voltage electrode 2 Test electrode APPLICATIONS In combination with a C tan measuring bridge the standard capacitor is used to measure loss factor and capacitance of a high-voltage test object. By using type 2801 the interfering stray capacitances can be eliminated completely by adjusting the screen system to the input potential of the bridge.

TECHNICAL SPECIFICATIONS Type 3388/100/25 Max. operation voltage EN 25 kV RMS Test voltage (1 min.) 30 kV RMS Rated capacitance C12 100 pF + 5% – 0% Time constancy of capacitance calibration value after 1 year < 0.01% Partial capacitances C10 ≈ 20 pF Test frequency 50/60 Hz -5 Dissipation factor tan δ of C12 2·10 Partial discharge up to rated voltage < 5 pC Gas filling SF6 Operating pressure Pabs at 20 °C 250 ± 50 kPa Test pressure Pabs 1100 kPa Temperature coefficient <1·10-4/°C Voltage coefficient (0…EN) <2·10-5 Admissible temperature range -20…+ 70 °C Relative humidity (at rated voltage EN)...