Enclosures

Enclosure temperatures
After a full fault some parts of an NER enclosure may be hazardously hot. The effects of this can be mitigated by labelling, by ventilation design and by enclosure construction that keeps the hot parts out of reach.
Bearing in mind that substations are not heavily populated and that faults are rare and never full duration, a solution that does not add disproportionate cost is obviously wanted: we consider that large, clear warning labels (Danger: hot surfaces) are the best approach.

Enclosure IP ratings
A well-ventilated enclosure allows more rapid cooling and so for a given duty less resistor material is required.
Given that the materials inside the resistor enclosure are stainless steels, ceramics and polyester/epoxy insulators, all suitable for unprotected outdoor use, we consider that enclosure ratings of IP23 are the right balance between good ventilation and the need to keep out birds and animals.
We do also offer IP55 enclosures where requested, either with or without filtration.

NER rated 13.8kV, 400A for 10 secondse.

Enclosure Materials and Design
Unpainted stainless steel (either 304 or 316) is now the preferred enclosure material, having better long-term corrosion, damage and heat resistance than painted or galvanized finishes at a comparable cost.
We offer single-box designs with bottom cable entry direct into the resistor compartment - this has the advantage of not leaving exposed lengths of cable - or with separate IP55 cable box.
This is more costly but can be a benefit at 11kV when NER-mounted ring-core CT's are being used, as they can be fitted in the base of the cable box around the incoming cable.