Switchgear: Fixed vs Removable 22 kV

[purplepete]

We are debating fixed vs removable for our next switchgear, 22 kV 1250 Amp about 20 panels two incomers, bus tie in the middle. Prot will be three layer (X,Y and backup)but probably not relevant. I'd really appreciate observations from anyone who has been through the same exercise. Anyone who has had grief is especially welcome, thanks. Our key issues are safety in racking in and out vs safety in maintenance and the need for a clear disconenct from the live bus.

 

[rbulsara]

For medium voltage, I have only seen removable (draw-out type) breakers in switchgear. Unless you mean fuse-switch by fixed.

Rafiq Bulsara

http://www.srengineersct.com

 

[Marmite]

It's interesting sometimes how Europe and the US go down different paths. In Europe most medium voltage SF6 and Vacuum switchgear used by the utilities is fixed pattern. Most manufacturers have settled on a design with a selector switch which moves from busbar-off-earth and the circuit breaker itself closes to earth the feeder for work. Many of the operational incidents which occur with old isolatable switchgear are connected with racking, such as test connections left in the spouts after testing, spanner left on the top of the circuit breaker truck etc. These are usually serious as the operator is right in the path of the blast. With fixed pattern gear the blast is deflected away from the operator towards the rear by design. Maintenance isn't an issue as essentially there isn't any maintenance other than trip testing and occasional mechanism checks/lubrication.
Regards
Marmite

 

[rbulsara]

I was thinking of industrial or commercial application. Perhaps the OP can clarify the application.

Rafiq Bulsara

http://www.srengineersct.com

 

[purplepete]

It's an industrial project with operators and maintenance personnel on site.

 

[davidbeach]

You get what you pay for, cheap or maintainable, you choose.