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LIVE HV NEWS
LIVE HV Goes Off-Line!
Live HV now provides Off-Line Partial Discharge monitoring for all switchgear and other high voltage equipment.
PD testing identifies insulation problems which traditional pressure testing and Megger testing can often fail to identify. This is why Power Utilities are now demanding an Off-Line PD test be carried out on their new switchgear prior to final commissioning.
The Off-Line PD test can be performed onsite and will detect discharge sites which factory testing may have missed; any damage during transit and more importantly any discharge due to incorrect installation such as a loose joint.
Off-Line testing can also be used to determine the discharge level of individual components such as Current Transformers, Voltage Transformers and Bushings.
Live HV has recently been working on an Integral Energy switchboard after an Off-Line PD test detected unacceptable levels of PD. Live HV successfully located the source of the discharge on the new 27 panel switchboard and repaired it.
Using Off-Line PD testing gear Live HV charged the switchboard and used a coupling capacitor to replicate the same levels of PD that Integral Energy had previously measured. Live HV then incorporated their On-Line PD testing gear into the Off-Line test and through a series of timing measurements were able to narrow down the PD site to a single chamber. Upon inspection of this chamber some loose bolts were quickly identified and tightened. After tightening the Off-Line PD test was repeated and the discharge had completely gone.
It was the combination of the On-Line and Off-Line sensors that proved such a great success in this case. The Off-Line testing was able to detect the serious problem which could not be identified by Pressure tests or Megger tests alone. The On-Line testing sensors then gave directions straight to the PD source in less than an hour of testing. It would have taken weeks of manually checking all the joints on the switchboard if the On-Line testing techniques had not been utilised.
Only Live HV can combine On-Line and Off-Line PD testing techniques for switchgear to enable both PD detection and location.
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This is rightly so when one witnesses a flashover inside switchgear. These arc faults can cause catastrophic damage taking out an entire switchroom and anyone unfortunate enough to be in the area.
Complete replacement is often difficult both financially and due to the downtime required. Retrofitting oil circuit breakers for vacuum and strengthening of panels can certainly help reduce the possibility and severity of an explosion and PPE can limit the personal damage if an event occurred.
However, if there was the possibility of a bomb inside your car you would opt for an inspection of the car instead of driving in a bomb suit or PPE. In much the same way PD testing can be used to locate and detect any potential ticking time “bombs” before they cause any damage to equipment or personal injury.
Many plant owners perform a range of high voltage tests to detect any problems and reduce their risk of a Flashover. PD testing is the best test method available for locating potential insulation problems and will dramatically decrease the risk of an Arc Fault event. What’s more the PD test can be performed On-Line so there is no requirement for a shutdown during testing. |
Arc fault prevention has gained a lot of attention lately as people realise the importance of Safety around switchgear.