Electrical Room Ventilation

[lci]

I am looking for a good design guide for electrical room ventilation. The electrical room has MCCs, lighting panels and transformers. I have talked to transformer manufacturers and have been told that the heat load is 5% of the rated load. Does anyone have experience with other heat gains from the other sources, MCCs, starters ect.

I have looked at the ASHRAE books and did not find too much detail on the ventilation of electrical rooms. For instance the questions I have are; Should we push air into the room? (Should the room be under positive or negative room pressure, I would think that the room should go positive to keep the dust out). What type of filters should be used. These are the types of questions I like to have answered in a design guide. Any help would be appreciated.

 

[mdonner]

Heat load from each device is found in the device's data sheet.
Positive pressure will keep dust away but will consume more energy.
Filter type depends on the application requirements: MCC may be NEMA 1, 4, 14 etc, and may provide the required protection.
For high loads such as VSD, it is best to duct the hot air outside the room.

 

[psighi]

If the system was installed in the 70's or early 80's, and changes to the facility may have increased the heat gain from the panels and xfmr's, consider the effects of switching power supplies causing odd-order harmonics and neutral currents.