On-Line Partial Discharge (PD) Test Services

High Voltage Partial Discharge Ltd (HVPD) provides both On-Line and Off-Line Partial Discharge (PD) Test Services to an increasing number of electricity utility and industrial clients around the world.

PD Test Services are carried out by our team of highly trained Test Engineers who utilise the versatile HVPD Longshot™ Diagnostic PD Test Technology, PDGold© and ScopeControl© software and a range of On-line PD Sensors to provide the highest level of Partial Discharge assessment available in the marketplace.

Examples of HV Plant that have been PD tested by HVPD include:

• Cables and Cable Accessories (terminations and joints)
• Switchgear (AIS and GIS)
• Instrument Transformers (Voltage and Current)
• Power Transformers and Bushings
• Motors and Generators
• Surge Arrestors
• Capacitors
• Cable Sealing Ends

Recent PD Test projects have included:

• On-line PD Testing and PD Mapping of High Voltage Cables in the transmission voltage range of 132kV to 400kV.
• Online PD Mapping and TDR - Time Domain Reflectometry Measurement of MV and HV Cables.
• On-line PD Testing and PD Location of Medium Voltage Switchgear (3.3kV to 36kV) for a range of electricity distribution companies and private HV plant owners.
• On-line PD Testing of High Voltage Gas Insulated Switchgear (GIS) 66kV to 275kV.
• On-line PD Testing of 132kV to 220kV Outdoor High Voltage Cable Sealing Ends.
• On-line PD Testing of 25kV Outdoor Voltage Transformers (VTs) for a large electromotive traction customer.
• On-line and Off-line PD Testing of HV Motors and Generators for a range of electricity generation and industrial clients.

The Benefits of On-Line Partial Discharge Testing are:

• It is truly a predictive test, indicating insulation degradation in advance of the failure (the detection of 'incipient' faults).
• It is a non-intrusive test, requiring no interruption of service and is performed under normal operating voltage and load.
• It is a nondestructive test i.e. it does not test to failure or adversely affect the equipment under test.
• It does not use any overvoltages, thereby not exposing the tested equipment to higher voltage stresses than those encountered under normal operating conditions.
• Trending can be accomplished by storing results to allow comparison with future tests.
• In many instances the site of the partial discharge occurrence can be located within the test object, so the localised problem can be repaired.
• The cost to perform an On-line PD survey is relatively inexpensive compared with off-line testing, allowing annual surveys to be performed economically at most facilities.