Coupling
Capacitors and Measuring Dividers
Description :
High Voltage Coupling-Capacitors are used mainly for Partial Discharge Measurements in High Voltage Testing as per
IEC60270. The Measurements of Partial Discharge according to IEC is based on measurement of High Frequency
Voltage Drop across a Measuring Impedance in the Ground lead of the Test Object or of the Coupling Capacitor. Any
partial Discharges appearing in or on a Test Object Under High Frequency Charge Transfer between the high Voltage
Potential and ground give rise to a High Frequency Current. This current produces a voltage drop across the measuring
impedance which is connected to the partial discharge meter for evaluation, measurement and display.
Design :
Depending on the rated voltage the coupling capacitor may consist of one or more several capacitor units
connected in series.
Insulation :
The Coupling Capacitors are insulated for indoor use. The Capacitor CK 60 to CK 600 are Insulated. The low
inductance wound capacitor elements are installed in an insulating Cylinder and held in position with special fixtures.
They are carefully dried in high vacuum and impregnated with EHV grade oil. The insulation of the capacitor elements and
the dimensions of the insulating cylinder are designed for a test voltage of 120% of rated voltage.
Hermetic Sealing :
All oil insulated Coupling Capacitors are Hermetically Sealed against the outer atmosphere using a
metallic expansion bellow. This prevents absorption of moisture by the active parts or the insulating oil.
Mobile Base :
All type coupling capacitors are mounted on a mobile base with swivel wheels allowing ease of transport.
Electrodes :
Type CK 120, CK 150 have aluminium cast flanges, CK 300 and above are provided with suitably
dimensioned aluminium to toroidal electrodes for corona free operation up to rated voltage.
Electrical Connections :
All types of CK coupling Capacitors are equipped with an UHF coaxial socket for connection to
the Measurement Impedance. The neutral end of the lowest capacitor stage is brought to this socket. The measuring
cable socket of the oil insulated capacitors is protected against over voltage by gas filled surge diverters.
When the measuring cable is removed, the connection socket of all capacitor types must be short circuited by a shorting
Plug included in the supply. Grounding screw on the base is provided for connection of a ground lead.
Technical Data
