Proper Selection Of A Recloser – Part I
January 7, 2014
On the topic of selecting a recloser-whether oil circuit or encapsulated (also known as epoxy encapsulated vacuum interrupters)-it should be stated upfront that the selection process is no less a complicated process than selecting any other piece of power equipment. For investor-owned utilities, electric cooperatives, municipals, rural electric associations, and industrial customers alike, it’s a great benefit to take the time to speak to someone who specializes in sales and service of reclosers and related equipment about the process. The end goal is to select a recloser that’s uniquely suited to your needs, and the process begins by opening a conversation and finding the right tools to do the job.
At Solomon Corporation, our engineering and technical staff is unmatched in industry knowledge and field expertise. We understand the industry and the hardware. We’re always happy to share what we’ve learned and help our clients make choices that benefit their budgets, businesses, and end-users. In the rest of this two-part article, we’ll talk in broad terms about the proper selection of a recloser.
What is a recloser? In simplest terms, a recloser is a piece of equipment that protects an electrical distribution system from issues related to transient overcurrent. In the power generation and distribution industry, specifically here in the U.S., 80-85% of the faults along a distribution network are transient in nature. The recloser serves as a circuit breaker that “trips” when an overcurrent is detected to protect the line. The automatic reclosing function then restores power to the affected line after the fault clears. Some reclosers house their electrical contacts in a suspension of electrically-insulating oil. These oil reclosers have been a reliable part of the industry for many decades. There is, however, a newer technology that utilizes vacuum-sealed bottles to contain the arc. These are the encapsulated variety.
The two major recloser types:
OIL CIRCUIT RECLOSER: Built in the U.S. since 1937, oil reclosers are self-contained and oil-filled. The arc interruption takes place under the insulating oil or in a vacuum bottle. A small single-phase recloser may have 4-5 gallons of oil. Larger units may carry up to 45 or 50 gallons. An OCR can be hydraulically or electronically controlled.
ENCAPSULATED RECLOSER: This newer recloser technology has been around for about 20 years. Instead of oil as the insulating element, the encapsulated recloser contains the arc in a vacuum interrupter that is encapsulated in a resin-based bushing. Encapsulated reclosers often come with a higher initial cost, but require very little maintenance.