These standard fixed capacitors are especially built for high accuracy measurements. Because of their high insulation resistance, small selfinductance and dissipation factor, these standards may be used within large frequency ranges. DESIGN FEATURES The standard capacitors type 3320 are built as «threepoles» capacitors, as they are equipped with three electrodes. Solid dielectric used for their construction is applied to part capacitances C10 and C20 only; those named C12 having no solid dielectric and being practically loss-free. ACCURACY The value of main capacitance “C12 “ has an accuracy of 0.001 %. The other capacitances’ accuracy is within 0.1 pF. EQUIVALENT CIRCUTS FOR CAPACITORS For full accuracy measurements, only the calibrated capacitance C12 can be used, the partial capacitances C10 and C20 should be eliminated. As a protection against dust and moisture, capacitors are enclosed in housings filled with dry air (water content of dry air: 75...100 ppm resp. 60...80 mg/m3. We have equipped our standard air capacitors (< 1000 pF) with a drying agent (Silicagel). On the humidity indicator, mounted at the side, the humidity in the interior of the instrument can be controlled. The variable capacitor is constructed as a vacuumcapacitor. An artificial aging compensates the mechanical stresses of the plates and supports of the standard capacitors. The constancy with regard to time is remarkably increased by this method. The operating voltage may reach a maximum of 2000 V R.M.S. Each edge of metallic parts is rounded to avoid dispersion loss

External Housing (screen) Internal Housing (screen) Dry air Base Plate (screen) Electrode Plates 2 Electrode Plates 1 Plate Distance Plate Thickness Tune Capacitor Insulators Junction Bushings 1 and 2 LIST OF TYPES Type RELATED HAEFELY HIPOTRONICS PRODUCTS Capacitance and tan bridges 2840 and 2820a and accessories Resistance units series 3720 for tan standards Partial discharge detectors and accessories OFFICES: Europe Haefely Test AG Birsstrasse 300 4052 Basel Switzerland + 41 61 373 4111 + 41 61 373 4912 [email protected] China Haefely Test AG Representative Beijing Office 8-1-602, Fortune...