VCB

inspect the bare copper parts through the glass. If there was any air inside they would be tarnished.

if it is a ceramic device, apply a high voltage and see if you get any current flow.

If there is a full vacuum it will not conduct at rated voltage. Any gas inside will undergo breakdown/ionization and a current will flow

Dear aurizon

"apply a high voltage and see if you get any current flow."

How can we apply HV? Through Meggar? Is it the rated voltage? or How many times the rated voltage -to cause breakdown of gas? Pl clarify.

well, they typically use vacuum relays to switch RF, since high circuit Q can cause peak voltages that would ionize the same sized air gap they use a vacuum path that has nothing to ionize to create a plasma carried spark. Now you can get electrons into the vacuum space, but they would arc around the sides more easily.

If there is air inside 1000 volts might cause a small current to flow as this air gets ionized.

The relay would be megger safe. Test a new relay and then the suspect relay with the same voltage. If they both have zero current, the suspect relay is good. If not, then there may be a gradual leak in the suspect relay and it has slowly filled with air.

You can take berak down voltage test of Vaccum intruppter, by supplying high voltage graddully to the intruppter and check at what voltage it trip,from that u can check your braker is healthy or not for your specifed voltage level.

Musef Chisti.

Most vacuum breakers do not have provisions for detecting the pressure in the interrupter assemblies, as this would add another weak point for failure of the containment. The simplest test is to open the breaker. If the vacuum is compromised, the interrupter bottle will sizzle, then explode! The contacts are way too close to prevent arcing in air. This is why the manufacturer will always state in the safety notices that the door to the power cubicle (the area containing the vacuum bottles) should be fully secured when operating the breaker.

The recommended test is to remove the breaker from service, then apply at least rated voltage (for example, our 13.8 KV outdoor breakers are rated at 15.5 KV) across the open contacts. A High Potential Tester (Hi-Pot) is normally used for this purpose. If you test the insulation on your own power cables, then the same tester used for the cables will work. The minimum acceptable value of resistance depends on the voltage rating, but is typically 500 to 1000 M-Ohm or greater.