Partial discharge is an unavoidable problem of electrical components. It can be very dangerous and can cause complete damage to any electrical module. Electrical components like the switchgear are used to control the voltage even in very high load and due to high voltage stress, there is a greater chance of damage during Partial discharge (PD). Looking from the external side, it is almost impossible to know when and where the partial discharge did happen exactly. Routine check-ups are very helpful in preventing PD but in a robust network it is very difficult to maintain routine check-ups and detect the area where PD has happened. Therefore,testing switchgear thoroughly is vital for avoiding any sort of mechanical damage and the safety of the components.
Switchgear is a combination of electrical disconnects switches, fuses, circuit breakers. It is typically used to protect and isolate electrical equipments. The high voltage switchgear was invented at the end of 19th century. It is used to control motor and other electrical machines. The technology was improved from time to time and now it is used to control voltage up to 1,100 kV. In the field of electrical engineering, it is a very popular and useful component until now, from the time it was invented in the 19th century.
Classification of switchgear
• By the current rating
• By voltage class
• By insulating medium
• By construction type
• By IEC degree of internal separation
• By interrupting device
• By operating method
• By type of current
• By application
• By purpose
Protecting switchgear from PD can help to protect all the electrical components of the network from ultimate damage and also help to run the network uninterruptedly. So, you must always conduct testing switchgearfrom time to time.
The typical reason of partial discharge is high voltage stress and its effect is the damage of a small portion to solid or fluid electrical insulation. As a result, it is unable to bridge the space between the two conductors. PD generally occurs in gaseous, liquid and solid insulating medium and in the peak voltage condition, both in positive and negative.
Partial discharge measurement can localize the damaged part or area of an insulated system. In the case of a switchgear, transformer, or rotating machine (like motor or generator) PD can be detected by routine check-up of the insulating system.
Detection and measurement both are important for safety and stability of any network. Routine check-up definitely reduces the chance of PD, but it is also a very difficult job to maintain routine check-up especially in a robust network. PD testing is usually done for detecting and measuring.
Some of the popular tests to measure the partial discharge are:
• PC analytical software
• a parallel discharge detector
• high voltage connections
• a coupling capacitor of low inductance design
• a cable or other object used as a test subject
• a partial discharge detector
• a high voltage filter to reduce background noise from the power supply
Another process is PD cable mapping, typically used for measuring partial discharge. It is an automatic analysis of the reflectogram for locating insulation irregularities.
The LIVE HV Company provides high-quality partial discharge tests since the last 10yrs in the UK and Europe. Testing switchgear is highly recommended for the safety of any network to hold the stability of said network and LIVE HV is one of the best providers of this service.
Check out http://en.wikipedia.org/wiki/Partial_discharge for additional details.