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Is there any code section which specifies the minimum temperature requirement for outdoor electrical equipment? Can I install an equipment rated for minus 20 degree C in a place where general ambient cold temperature in winter is minus 40 deg C?

Thanks for your quick comments. When you commented about monthly start and test, it appears to me it is on no-load, so it will be probably a run duration of 5-10 minutes typically?

Please tell me CAN I NOT KEEP A EMERGENCY DIESLE GENERATOR IDLE FOR PROLONGED PERIOD? It is connected to a switchgear bus with utility connection on the other main. Utility supply rarely fails, so the emergency diesel gen is hardly used.

I am trying to find IEEE or any other standard (vendor neutral document) which discusses about different type of bus transfer scheme - namely slow transfer scheme, residual voltage transfer scheme etc. Any information about which IEEE standard or any other standarad discusses about those?

I am looking for a typical calculation for shaft voltage/ bearing current for VFD fed morors. Can you please tell me about any similar resources or papers - how to do those calculations? I understand that less than 300 mV shaft voltage is safe.

If a breaker trip on transformer inrush current just after closing, is it an arc flash hazard?

Can anybody tell me where can I get a typical diagram for connection of one power meter and one protection relay on one common CT set(Three phase). The case here is originally built with one relay, now want to add a meter on the same CT set and PT set.

Do 13.8 kV overhead line needs ground fault protection per NEC? This 3 wire O/H ACSR line fed from transformer delta winding (step-up) with no intentional grounding and connected to delta winding at other end (step-down).