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R E R6 20
A DVA N C ED R EC LOSER P R OT EC T I O N & CO N T R O L
4. Application
To make ordering simple, the RER620 always in-
cludes three phase CTs, sensitive earth fault (SEF)/
high impedance (HIZ) CT input and six VT inputs to
perfectly match required distribution feeder pro-
tection, control and metering functionality. Cus-
tomer programmable phase and ground CT and VT
secondary nominal settings and wide protection
setting ranges increase the RER620 flexibility of
application. Directional ground-fault protection is
mainly used in isolated neutral or compensated
networks, whereas non-directional ground-fault
protection is intended for directly or low imped-
ance grounded networks. The protection and con-
trol relay can also be used for protection of ring-
type and meshed distribution networks as well of
radial networks containing distributed power gen-
eration.
Measured residual current from the fourth CT input
(0.2/1A) is used by the Sensitive Earth Fault and
High Impedance Detection. The residual current for
the ground-fault protection derived from the phase
currents is used by other time overcurrent and in-
stantaneous ground protective elements. When ap-
plicable, the core-balance current transformers can
be used for measuring the residual current, espe-
cially when sensitive ground-fault protection is re-
quired. In the case when high sensitivity is required
to detect the fault in the range of 1A primary cur-
rent, protection functions can be set to the fourth
CT input with 0.2A nominal tap setting.
The standard configuration offers directional
earth-fault protection with residual voltage calcu-
lated from the phase voltages. Furthermore, the
standard configuration include fuse failure supervi-
sion. In addition standard configuration offers di-
rectional overcurrent protection, overvoltage and
undervoltage protection, positive-sequence and
negative-sequence overvoltage protection and re-
sidual voltage protection.
To perform automatic loop restoration functions,
commonly accepted as a means to significantly im-
prove circuit reliability and to provide more effec-
tive system operation, embedded Loop Control
functionality is provided as a standard feature. In
such applications there is no communication be-
tween the recloser control protection and control
relays and automatic fault isolation and restoration
is accomplished with Loop control functionality.
The loop control feature in RER620 supports
(please refer to Figure 4):
Sectionalizing recloser:
Opens in response to a downstream fault or to a
loss of phase voltage from an upstream circuit.
Midpoint recloser:
It supports loop control by automatically altering
the RER620 settings in accordance with changing
voltage conditions.
Tiepoint recloser:
It closes in response to a loss of all phase voltages
from one source if the other source phase voltages
are live.
In the case there is a communication (via fiber-op-
tic or wireless) between recloser control relays, net-
work reconfiguration can be accomplished by
GOOSE messaging based on IEC61850, please refer
to Figure 2.
To ensure that energization of Distributed genera-
tion interconnection transformer does not cause
the protective elements at already installed re-
closer to operate (because of transformer inrush
current), RER620 have built in logic to detect ener-
gization and consequently make necessary action
such as desensitize or block protective elements.
With this RER620 advanced feature, need for the
external wireless communication as well as com-
plex relay blocking logic and operational proce-
dures are avoided, please refer to Figure 3.
Included is advanced Ethernet communications
supporting the IEC61850-8 standard and DNP3
Level 2+, IEC 60870-5-104 and Modbus protocols
over TCP/IP, and serial communications supporting
DNP3 Level 2+, IEC 60870-5-101, Modbus and PG&E
2179 protocols.
The standard configuration includes six voltage
sensing inputs. Each sensing input can accommo-
date conventional voltage sources as well as capac-
itive and resistive voltage dividers (sensors) that
provide low level voltage magnitude.
Inaccuracy of the voltage sources (conventional and
sensor type) can be compensated by setting in
RER620.
