ABB RET670 Product Manual page 17

ABB
Transformer protection RET670
Pre-configured
Product version: 1.1
Pole discordance protection CCRPLD
Single pole operated circuit breakers can due
to electrical or mechanical failures end up
with the different poles in different positions
(close-open). This can cause negative and
zero sequence currents which gives thermal
stress on rotating machines and can cause
unwanted operation of zero sequence or
negative sequence current functions.
Normally the own breaker is tripped to
correct such a situation. If the situation
persists the surrounding breaker should be
tripped to clear the unsymmetrical load
situation.
The Polediscordance protection function
CCRPLD operates based on information from
auxiliary contacts of the circuit breaker for
the three phases with additional criteria from
unsymmetrical phase current when required.
Directional over/underpower protection
GOPPDOP/GUPPDUP
The directional over-/under-power protection
(GOPPDOP/GUPPDUP) can be used
wherever a high/low active, reactive or
apparent power protection or alarming is
required. The functions can alternatively be
used to check the direction of active or
reactive power flow in the power system.
There are number of applications where such
functionality is needed. Some of them are:
• detection of reversed active power flow
• detection of high reactive power flow
Each function has two steps with definite
time delay. Reset times for every step can be
set as well.
Broken conductor check BRCPTOC
The main purpose of the function Broken
conductor check (BRCPTOC) is the detection
of broken conductors on protected power
lines and cables (series faults). Detection can
be used to give alarm only or trip the line
breaker.
1MRK 504 091-BEN B
Voltage protection
Two step undervoltage protection
UV2PTUV
Undervoltages can occur in the power system
during faults or abnormal conditions. Two
step undervoltage protection (UV2PTUV)
function can be used to open circuit breakers
to prepare for system restoration at power
outages or as long-time delayed back-up to
primary protection.
UV2PTUV has two voltage steps, each with
inverse or definite time delay.
Two step overvoltage protection OV2PTOV
Overvoltages may occur in the power system
during abnormal conditions, such as, sudden
power loss, tap changer regulating failures,
open line ends on long lines.
Two step overvoltage protection OV2PTOV
can be used as open line end detector,
normally then combined with directional
reactive over-power function or as system
voltage supervision, normally then giving
alarm only or switching in reactors or switch
out capacitor banks to control the voltage.
OV2PTOV has two voltage steps, each of
them with inverse or definite time delayed.
OV2PTOV has an extremely high reset ratio
to allow setting close to system service voltage.
Two step residual overvoltage protection
ROV2PTOV
Residual voltages may occur in the power
system during earth faults.
Two step residual overvoltage protection
ROV2PTOV calculates the residual voltage
from the three-phase voltage input
transformers or from a single-phase voltage
input transformer fed from an open delta or
neutral point voltage transformer.
ROV2PTOV has two voltage steps, each with
inverse or definite time delayed.
Issued: June 2010
17