11kV Switchgear Two tier (high) v/s one tier (high) construction

[krisys]

We are replacing the existing 40 years old 11kV switchgear with a new switchgear. This is the switchgear is the main switchboard in this offshore facility. It is supplying very important loads in the facility. I am not terming the loads as critical loads, as critical loads require UPS or DG Supply as back up!

The existing old switchgear is single tier (One high, in the North American parlance). The consultant is recommending two tier (Two high) arrangement for the new switchgear. This selection would result in increased number of spare feeders for the future use.

Barring the increased number of spare feeders, there was no other criteria.

I am of the view that for the important application like this, the two tier switchgear should not be used. It would be difficult to perform inspection and maintenance. More risk exposure of working personnel to the high voltage. Cable termination will be difficult etc.

I would appreciate if someone could analyze the pros and cons of two tier switchgear.

 

[LionelHutz]

Metal clad switchgear or metal enclosed switchgear?
Vacuum breakers or disconnect switches and fuses?
What kind of inspections are you thinking become more difficult?

 

[dpc]

It's very common - at least in the US. Things get a little tighter, but I don't see the other concerns you're worried about. A breaker lift/hoist will be required, even with one-high construction.

Have you looked at two-high switchgear? If you've got a lot of space and money, nothing wrong with the one-high concept, of course.

 

[ScottyUK]

Of greater concern to me would be draw-out versus fixed-pattern. I'd take draw-out every time. Our 2-high draw-out stuff is maintainable without undue effort.