RECLOSERS
Automatic Circuit Reclosers (ACRs) are a class of switchgear which is designed for use on overhead electricity distribution networks to detect and interrupt momentary faults. Also known as Reclosers or Auto-reclosers, ACRs are essentially medium voltage rated circuit breakers with integrated current and voltage sensors and a protection relay, optimized for use as an overhead network distribution protection asset. Commercial ACR's are governed by the ANSI/IEEE C37.60, IEC 62271-111 and IEC 62271-200 standards. In ANSI countries three major classes of operating voltage are 15.5 kV, 27 kV and 38 kV.
For overhead distribution networks, the majority of faults are transient, such as lightning strikes or foreign objects coming into contact with the exposed distribution lines. By this logic, 80% of outages can be resolved by a simple re-close operation. Reclosers are designed to handle a short close-open duty cycle, where electrical engineers can optionally configure the number of attempted close operations prior to transitioning to a lockout stage.
Invented in the 1950s in the USA, reclosers were originally oil filled devices with rudimentary mechanical protection relaying capabilities. Modern Automatic Circuit Reclosers are significantly more advanced than the original hydraulic units. The advent of semiconductor based electronic protective relays in the 1980s resulted in increased sophistication, allowing for differing responses to the various cases of abnormal operation or fault on distribution networks. The high voltage insulation and interrupting device in modern reclosers typically consist of solid dielectric insulation with vacuum interrupters for current interruption and arc suppression.
Reclosers are often used as a key component in a smart grid as they are effectively computer-controlled switchgear which can be remotely operated and interrogated using SCADA or other means of communication. This capability allows utilities to aggregate data about their network performance, and develop automation schemes for power restoration. This automation can either be distributed or centralized.
Vacuum interrupters for Auto-Reclosers
| Rated Voltage |
Rated lightning impulse voltage |
Power frequency withstand voltage |
Rated Current |
Short circuit breaking current |
VI Type
(Dia.-Style) |
| kV |
kV |
kV |
A |
kA |
|
| 15.5/27 |
110/125 |
50/60 |
630 |
12.5 |
M52QC*
(φ65-B) |
| 15.5/27 |
110/125 |
50/60 |
800 |
16 |
M72QC*
(φ75-B) |
| 38 |
150 |
70 |
630 |
12.5 |
M83QC*
(φ75-B) |
| 38 |
150 |
70 |
800 |
16 |
M93QC*
(φ82-B) |
