15 kv switch gear

[Sparks 1]

We have several sections of 15 kv switchgear at a paper mill I work at. This gear is used to feed a drive isolation transformer operating at 480 volts that supplys power to say 5 dc drives. They are load break rated switches. How often do these switches have to be inspected. The manufacturer I believe states 300 with no load condition. I think 19 for loaded condition. Our supervisor states this to be a no load condition which in my opinion is incorrect because upon powering up the ampmeter is pegged instantly for small period of time . This shows it to be a loaded condition and not no load as it is picking up the transformer and granted the drives are shut off but one is still picking up the transformer. We are also opening this switch with the drives off but transformer still energized. The question has been brought up about them doing the arc flash study and reducing this to a level 1 because of the fusing and time study involved. I think I could agree with some of this if it were an isolated no load closure of the switch but can't agree because it instantaeously energizes a transformer shown by the ampmeter.

Thanks,
Spark 1

 

[jim dungar]

Load-No Load switching usually refers to the 'turning off' operation at 100% rated load.
The fact that these switches 'are' or 'are not' fused should not impact the arc flash results. Incident energy is impacted by the device protecting these switches, on their line side.

 

[zog]

The inspection and maintenence intervals will be listed by the OEM in the IB, whcih I could post for you if I knew what type of switch it is. Or you can follow recommended inspection/maintenence intervals from NFPA 70B or ANSI/NETA