OSM-Longshot™ On-Line Partial Discharge Test Technology

OSM-Longshot™ Portable PD Monitor (shown with Transponder for HV Cable Mapping)	High Frequency Current Transformers (Type: HFCT 140/100) (connected around the cores with 33kv cables)	OSM-Longshot™ Monitor - Cable PD Testing in the Substation

Over the last 10 years IPEC High Voltage Ltd have developed a range of On-Line Partial Discharge Test Equipment for the Worldwide Electricity Supply Industry.

New for 2007, the OSM-Longshot™ Portable PD Monitor with PDGold© v5.0 Software utilises a unique 'Event - Recogniser ©' Software Module which automatically sorts all detected pulses into type of discharge and noise, providing an instant, online insulation diagnostic tool for the customer.

The OSM-Longshot™ PD monitor is suitable for partial discharge testing of most types of high voltage plant, including:

• MV and HV Cables
• MV and HV Switchgear (AIS and GIS)
• Transformers and Bushings
• Motors and Generators
• CT's and VT's
• Cable Sealing Ends

PD Measurements are made using a range of Calibrated PD Sensors supplied by IPEC HV. These are either inductively, capacitively or acoustically coupled to the equipment under test, to provide on-line PD testing with the equipment 'live' (no outage required). The technology can also be applied effectively within the Laboratory or Test station to provide conventional, off-line PD measurements to IEC requirements and/or Wideband requirements.

The OSM-Longshot™ Technology has been designed to be very flexible and is suitable for both 'PD Spot Testing' and 'Portable PD Monitoring' as follows:

Mode 1 - Spot-Testing Mode - The unit is used to collect PD data for typically a few minutes per test, thereby allowing large numbers of HV plant items to be tested and 'screened' for PD quickly and easily.

Mode 2 - Monitoring Mode - The monitoring unit is connected to the plant under test for an extended period to collect short-term monitoring data. (For example, the unit can be left for 24 hours to monitor PD over the load cycle).

The OSM-Longshot™ PD Monitor system is based around large-memory, wideband digital waveform data acquisition hardware which is provided by a range of calibrated, high-specification Digital Storage Oscilloscopes (DSO's) with built-in PC's. The unit is suitable for both Online and Offline PD Testing

PD data processing, analysis, separation and identification of partial discharge signals is carried out in the integrated PDGold © and PDReader © Software. This software automatically differentiates PD from 'noise' originating from insulation defects in high voltage electrical apparatus, such as cables, switchgear, generators, motors, etc…

• The PDGold © Software captures PD signals synchronously across the 50Hz (or 60Hz) power cycle allowing the user to observe familiar phase-related patterns of discharge, online and in real-time.
• The PDReader © Software provides an automatic PD 'Criticality' Level for the plant under test based on magnitude and number of PD pulses (count) per power cycle.
• PD levels in HV cables and other plant can measured in pC (picoCoulombs) as standard when used with Calibrated PD Sensors (without the need for an external pC Calibrator).
• The PDReader © Software contains the unique 'Event Recogniser ©' Module which applies easy-to-understand, knowledge-based software to provide PD Pulse Discrimination into type of PD (cable PD, switchgear PD etc) whilst automatically pre-sorting out electrical 'noise' pulses.
• The PDReader © Software includes an automatic 'RF Noise Reduction' function which uses 'single frequency spectral subtraction' to reduce RF noise.
• The new technology is compatible with the On-line Cable Mapping Package from 'IPEC HV' which provides for the location of PD Sites along the length of HV Cables of up to 5km in length.

On-Line PD Sensors:

IPEC HV supply a wide Range of PD Sensors and accessories including:

• Shielded, Calibrated High Frequency Current Transformers (HFCT's)
• External Capacitive Coupler (TEV) Sensors
• Airborne Acoustic and Contact Acoustic Probes with amplifiers
• A complete set of PD Test accessories including co-axial cables, decouplers etc.

Examples of Software User Interface Screen