Very often a panel enclosure is located near ground level on distribution lines, In this article Electrical Engineering shares what is purpose of this panel.
The grey enclosure located near ground level on this pole contains the protective relay responsible for issuing the “trip” and “close” signals to the recloser’s coils. Current transformers located within the recloser provide isolated sensing of line current to the reclosing relay, necessary for detecting any overcurrent conditions that might result from a transient fault. Each attempt by the reclosing relay to re-close the breaker is called a shot. If the reclosing relay fails to clear the fault by a certain number of shots, it enters the lockout state whereby the recloser remains open and must be re-closed by human intervention.
So What exactly is a recloser?
The recloser is a special type of medium-voltage circuit breaker used to quickly interrupt and re-establish power in distribution lines.
Reclosers are designed to trip if ever a distribution line suffers a “transient” (momentary) fault due to some natural event such as a lightning strike causing an insulator to “flash over” to ground or a tree branch touching one or more line conductors, then automatically re-close moments later to test whether or not the fault still persists. If the fault clears on its own – a common occurrence with tree branches, as the branch may break off or burn away following the initial arc – then the recloser remains closed and continues providing power to customers. By some estimations transient faults account for 70% to 90% of all faults occurring on overhead power lines. If non-reclosing fault protection were applied to all distribution and transmission lines, extended interruptions of electric power service would be far more common than they are now.
Continue reading article on Reclosers here
Also read:
- What is Feeder in Electrical Power System
- What is Distributor in Electrical Power System
- What is service mains in power distribution system
- What is basic difference between Feeders, Distributor, and Service mains