-40F electrical installations
-40F electrical installations
(OP)
I occasionally build water delivery systems for areas that are very cold like -40F/-40C. These systems include electrical equipment like disconnects, relays, circuit breakers, etc. Often the electrical systems are installed external to the building. How do you handle these cold environments as it relates to the selection of the electrical components, short of placing them indoors where it is warmer. Which is not always possible.
Thanks for your help
Thanks for your help






RE: -40F electrical installations
Bill
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"Why not the best?"
Jimmy Carter
RE: -40F electrical installations
RE: -40F electrical installations
Dew point condensation in "blade" style backplane panels can lead to corrosion and eventual arcing that burns the blade off the backplane. For this reason in addition to the heater suggested above, would recommend using only panels where the breakers use a bolted connection to the backplane, rather than the blade style backplane relying on breaker contact spring force to maintain an adequate connection.
Have also experienced copper creep leading to loosened connections with certain types of wire lugs found on breakers. If your -40 environment also includes major temperature swings, would expect you might see connections loosen over time.
RE: -40F electrical installations
Copper resistance heat load increases as well as current flows in summer? The box won't always be outside in the very cold.
RE: -40F electrical installations
Transformers could be designed by the manufacturer to keep the oil without getting freeze or consider additional space heaters.
Gas insulated circuit breakers or insulated with SF6 could used heated blankets for dead-tank design. For live tank design or dead- tank without heaters, breakers could work satisfactorily at -50C With a gas mixt of SF6 and Nitrogen or a mixt with SF4. For low temperature cycle test IEC std 56 could be used as reference.
Air disconnect switches should be mechanically design for ice break at operating temperature.
Gas insulated substation could be an option for outdoor application with a combination of heater and gas mixt and pressure increase.
RE: -40F electrical installations
Thanks.
RE: -40F electrical installations
RE: -40F electrical installations
Again thanks for all the guidance.
RE: -40F electrical installations
Check with manitoba Hydro or the local utility in Canada to see if any reference or standard that could be used safe for your application.
RE: -40F electrical installations
They have unique Approval processes that you may want to use some 'local expert' to help you.
But we use thermostatically-controlled strip heaters at my utility here in Canada, sometimes more than one stage with different temperature set-points.
An adequate amount of heating for 0°C (32F) may be too little for -40°C/F, and will be way too much for +40°C (104F).
It does get kinda hot in Canada too, sometimes.
In addition, running heaters 24/7/365 wastes power if they are not needed all of the time.
In my metal-clad substation buildings, I have heaters, automatic ventilation louvers, and forced-air cooling (all connected to thermostats) to cover the ambient temperature variations.
RE: -40F electrical installations
As always thanks for the help.
RE: -40F electrical installations
RE: -40F electrical installations
When I was in Apparatus Maintenance in southern Manitoba, we used a 50/50 mix of sf6 and cf4. I'm not sure if that has changed though, I've been in Generation North for a little more than a decade now.
RE: -40F electrical installations