Condensation Heaters

[SparkyLarks]

I've installed a prefabricated switchroo. It comes on a module onLegs.

The temperature in the module is kept at 20degC

However as the MV cables wnter the switchgear through a gland plate in the floor. A questin has been raised regarding the posibility of condensation in the switchgear.

There is a steel plate gland on the bottom of the switchgear and approximately 200mm below that there is an aluminium plate. The question is is the radiant heat fro the side walls of the MV switchgear enough to over come the cooling effect from the possibly colder plate on the bottom of the switchgear.

I'm not really sure where to start, I've passed the query on to the switchgear manufacturer but would like to try to figure it out on my own in the background.

Is the danger from when warm air would would fill a Cold MV compartment, rathern thatn a danger from Cold Air Getting into the MV Compartment.


The Switchgear will be installed in the middle of the Uk so the Air temperature will be -5Deg to 30 Deg.

 

[ScottyUK]

If your incoming cables are single cores then you'll probably have a heater in the form of the steel glandplate. You should not have a ferrous loop around any individual conductor otherwise it will experience induction heating. With high current circuits the effect can be quite dramatic - hot enough to burn paint and liquify galvanised finishes.

Your installation sounds fairly typical other than the above - you might want anti-condensation heaters if the board could be de-energised for any prolonged period.


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[SparkyLarks]

Well Aware of the heating issue with Single cores and Steel Gland Plates. The switchgear maunfacturer insisted that we use the supplied type tested steel plate. The Plate has been sectioned into 3 parts to allow a gap between the metal plates.

You say " you might want anti-condensation heaters if the board could be de-energised for any prolonged period."

My question is how do I determine that
1) What a prolonged period is, is it days , weeks?
2) Given 1 how do I determin if I need it. I can just put them in to be safe but I prefer to have some sort of quantative back-up.

 

[waross]

Condensation often forms during a rise in ambient temperature. If the ambient temperature rises to the point that the dew point is above the temperature of the components inside the switch gear, condensation will form on the cold parts. You just need to add enough heat to keep the interior above the dew point. Often too heaters are run in series with 1/2 rated voltage supplied to each, 24/7. No thermostat to fail and the heaters will last indefinitely on 1/2 voltage.

Bill
--------------------
"Why not the best?"
Jimmy Carter