Switchgear and Transformer Clearances/Location
Switchgear and Transformer Clearances/Location
(OP)
Hi All,
First question:
We have a new 500kVA, 13.8kV/600V dry-type ventilated transformer to be installed in a new electrical room. The dimensions of the electrical room is sufficient so real estate is not a concern here. My main concern would be the most ideal location of the transformer; either against the wall with about 1ft clearance for ventilation purposes or about 3-4 ft away from the wall. I would prefer the first option, but that might not be the best from a maintenance point of view as well as cable terminations for a transformer of this size. Any thoughts/comments?
Second question:
Facing the 500kVA transformer is a new 15kV MV Metal-Enclosed Switchgear. My questions here is the clearance required between these two equipments. Table 56 of CEC 2006 states that 1.9m is needed as a minimum working space for that voltage class. Do I need to apply that minimum clearance for my application here? Or would just 1m, as stated 2-308 CEC 2006, suffice as clearance between the two equipments. It's less than a meter difference (i.e. 1.9m vs 1m) here but it is the concept that I would like to understand.
As this is a new installation, I'm free to move around to ensure clearances and egress are met.
Appreciate any comments/thoughts?
Regards,
Sonic
First question:
We have a new 500kVA, 13.8kV/600V dry-type ventilated transformer to be installed in a new electrical room. The dimensions of the electrical room is sufficient so real estate is not a concern here. My main concern would be the most ideal location of the transformer; either against the wall with about 1ft clearance for ventilation purposes or about 3-4 ft away from the wall. I would prefer the first option, but that might not be the best from a maintenance point of view as well as cable terminations for a transformer of this size. Any thoughts/comments?
Second question:
Facing the 500kVA transformer is a new 15kV MV Metal-Enclosed Switchgear. My questions here is the clearance required between these two equipments. Table 56 of CEC 2006 states that 1.9m is needed as a minimum working space for that voltage class. Do I need to apply that minimum clearance for my application here? Or would just 1m, as stated 2-308 CEC 2006, suffice as clearance between the two equipments. It's less than a meter difference (i.e. 1.9m vs 1m) here but it is the concept that I would like to understand.
As this is a new installation, I'm free to move around to ensure clearances and egress are met.
Appreciate any comments/thoughts?
Regards,
Sonic






RE: Switchgear and Transformer Clearances/Location
Question: Do you need to go between the transformer and the switchgear for maintenance, and is it an arc-flash concern?
Question: If there was a fire in the room, how much space do you need between the equipment?
Not that I know the answers, I just believe these are good questions which might lead to your answers.
RE: Switchgear and Transformer Clearances/Location
Your points noted. Any other thoughts/comments anyone?
RE: Switchgear and Transformer Clearances/Location
ventilation purpose. The 13.8 kV side shall be against the wall and a kind of barrier should be provided in front of low voltage side.
Another solution it is a Metal clad substation where the transformer could be supplied complete with an integral IP31 sheet steel enclosure, with termination boxes and switchgear if required. See IEEE Redbook "Unit Substations"ch.10.5. See -for instance:
h
A fire resistance wall could be provided between transformer without enclosure and a switchgear if the NEC recommended distance is not possible.
NEC art.450.21 required 1.83 m [6 ft] horizontal from a non-fire resistant enclosure. A completely enclosed transformer [except for ventilating openings] does not require any distance from such an enclosure.
RE: Switchgear and Transformer Clearances/Location
ISTR that, in North America, typical listed drytypes have clearance requirements stated either on the label or packed with the transformer.
RE: Switchgear and Transformer Clearances/Location
RE: Switchgear and Transformer Clearances/Location
Jimi Young - civilian
184th CES/Electrical Shop
Ks Air Nat'l Guard
McConnell AFB, KS