Heat losses from large switchboards
Heat losses from large switchboards
(OP)
Hello,
We have an installation with a total of four switchboards whose combined bus load rating is 13.75 MVA in one room. There are four switchboards made up of Metal Enclosed Low Voltage Switchgear. While giving the Mechanical fellows our anticipated heat loads for the transformers in the room, it occured to me that the "rule-of-thumb" that I normally use to allow for heat loss into the room from loaded switchgear, (I have used a 1% figure for years-don't really recall where I got that), is quite a load in this case, (over 171kW). Does anyone know of published data on this? I've looked through manufacturer's websites and have a call into my switchgear rep, but I was just curious as to other's experience.
We have an installation with a total of four switchboards whose combined bus load rating is 13.75 MVA in one room. There are four switchboards made up of Metal Enclosed Low Voltage Switchgear. While giving the Mechanical fellows our anticipated heat loads for the transformers in the room, it occured to me that the "rule-of-thumb" that I normally use to allow for heat loss into the room from loaded switchgear, (I have used a 1% figure for years-don't really recall where I got that), is quite a load in this case, (over 171kW). Does anyone know of published data on this? I've looked through manufacturer's websites and have a call into my switchgear rep, but I was just curious as to other's experience.






RE: Heat losses from large switchboards
Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.
RE: Heat losses from large switchboards
Rafiq Bulsara
http://www.srengineersct.com
RE: Heat losses from large switchboards
After summarizing all heat from BCs I added about 30% of total quantity representing busbars and all cables and wires in the rooms. Then I multiplied it by the coefficient 0,6 (similarly with the coefficient of the simultaneousness, however higher a bit than this one of electrical circuits, being roughly 0,45 for my building). My results were about 28kW total heat in comparison to 8MW of electrical total (maximum) power. So your 1% in my oppinion is too much, I think that should be less than 0,4% or even 0,3% (in my case it was about 0,35%, however it was in 3 rooms).
I hope you may take this Schneider's data "per analogiam" or get your own from the producer of your equipment.
Regards
RE: Heat losses from large switchboards
The enclosed Excel sheet is Ok, apart from a bloomer that at the "D" column should have the title "Heat (for 3 poles)".
RE: Heat losses from large switchboards
RE: Heat losses from large switchboards