ABB RER620

Section 5 1MAC309294-MB F
Control functions
306 RER620
Technical Manual
The autoreclose function can be used with every circuit breaker that has the ability for a
reclosing sequence. In 79 autoreclose function the implementing method of autoreclose
sequences is patented by ABB
Table 294: Important definitions related to autoreclosing
5.2.7.1 Single Phase Tripping
The RER620 single-phase tripping and reclosing option is advantageous for use on many
electric utility distribution systems, including rural, residential and some commercial
loads. It provides a control capability function of the recloser to trip and/or lockout
whenever there is a fault on one-phase, two-phases or three-phases. This feature allows an
electric utility to prevent unnecessary three-phase interruptions and outages of their
distribution network where a majority of outages can be attributed to single-phase transient
type faults thereby improving the overall power system reliability and quantity of power
delivered to customers on the distribution feeder.
Overview of the features in single-phase tripping
As an example of single-phase operation of an RER620 with a recloser, imagine that the
recloser is protecting a rural three-phase line. Suppose that a fault occurs on A-phase,
where the fault is permanent and there is no fuse between the recloser and the fault. A
conventional three-phase recloser will trip for two instantaneous operations followed by
two time-delayed operations. The single-phase fault on A-phase will cause all customers
downstream to experience three interruptions of power and an outage until the fault is
repaired, cleared and the recloser restored to normal operation. The RER620 with
single-phase tripping can operate the recloser for the same single-phase fault on A-phase
as a single-pole trip, reclose and lockout. This provides a significant advantage to 67% of
the customers downstream of the fault since their power is not interrupted. The operation
of single-phase operation will trip for two instantaneous operations, two time-delayed
operation and lockout on the A-phase pole. Since the fault is a permanent
single-phase-to-ground fault, (e.g. A-N), the load connected to A-phase will experience an
outage but the other two phases (e.g. B-phase and C-phase) will not experience any
interruption of power and will stay energized.
The single phase tripping option is designed to be extremely flexible in order to meet the
most demanding requirements. Listed below are brief descriptions of the features for
single-phase and three-phase tripping operation:
RER620s supplied with the single phase tripping option consist of the same hardware
(front panel and modules) as the standard three phase units. Settings for single phase
autoreclose shot an operation where after a preset time the breaker is closed from the breaker tripping
caused by protection
autoreclose
sequence
a predefined method to do reclose attempts (shots) to restore the power system
SOTF
If the protection detects a fault immediately after an open circuit breaker has been
closed, it indicates that the fault was already there. It can be, for example, a forgotten
grounding after maintenance work. Such closing of the circuit breaker is known as
switch on to fault. Autoreclosing in such conditions is prohibited.
final trip Occurs in case of a permanent fault, when the circuit breaker is opened for the last
time after all programmed autoreclose operations. Since no autoreclosing follows, the
circuit breaker remains open. This is called final trip or definite trip.