Voltage Protection - Hitachi Relion 670 Series Product Manual

Line differential protection RED670
Version 2.2
Peak and Peak-to-Peak measurement mode allow this
function to be used as instantaneous over-current protection
as well. If required by application, short time delay can also
be applied.
BRPTOC can be used for different line and transformer
protection applications. If required, it can also be used to
supervise on-load tap-changer operation.
Pole discordance protection CCPDSC
An open phase can cause negative and zero sequence
currents which cause 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 breakers
should be tripped to clear the unsymmetrical load situation.
The Pole discordance protection function (CCPDSC)
operates based on information from auxiliary contacts of the
circuit breaker for the three phases with additional criteria
from unsymmetrical phase currents 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 a 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.
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.
Voltage-restrained time overcurrent protection
VRPVOC
Voltage-restrained time overcurrent protection (VRPVOC)
function can be used as generator backup protection
against short-circuits.
The overcurrent protection feature has a settable current
level that can be used either with definite time or inverse
time characteristic. Additionally, it can be voltage controlled/
restrained.
One undervoltage step with definite time characteristic is
also available within the function in order to provide
functionality for overcurrent protection with undervoltage
seal-in.
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SEMOD175421-4 v7
SEMOD171446-5 v2
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Average Power Transient Earth Fault Protection
APPTEF
The APPTEF (Average Power Transient Earth Fault
Protection) function is a transient measuring directional
earth-fault protection. Determination of the earth fault
direction is based on the short-term built-up transient at the
beginning of the earth fault. This transient is to a large
extent independent of the neutral point treatment. This
means that the function can be used without any
modification in all types of high-impedance grounded,
resonant grounded or isolated power systems.
For a resonant grounded system, the correct directional
measurement is ensured regardless of how many Petersen
coils are used throughout the interconnected power
network. The function is not sensitive to the actual
compensation degree of the coils. It will operate equally well
in an under- or over-compensated system. Parallel neutral
resistor to the Petersen coil are not needed to correctly
determine earth fault direction. However, these neutral
resistors can still be used if already installed in the network.
The function is suitable to be used in distribution and in
meshed HV sub-transmission networks using high-
impedance grounding. In meshed systems a directional
permissive scheme is required in order to ensure selective
tripping of a faulty line. Alternatively, the function can be
used solely for signaling of the earth-fault location to the
SCADA system when the power network is allowed to
operate for a longer time with an earth-fault being present.

8. Voltage protection

Two-step undervoltage protection UV2PTUV
Undervoltages can occur in the power system during faults
or abnormal conditions. The two-step undervoltage
protection function (UV2PTUV) can be used to open circuit
breakers to prepare for system restoration at power outages
or as a long-time delayed back-up to the primary protection.
UV2PTUV has two voltage steps, each with inverse or
definite time delay.
It has a high reset ratio to allow settings close to the system
service voltage.
Two step overvoltage protection OV2PTOV
Overvoltages may occur in the power system during
abnormal conditions such as sudden power loss, tap
changer regulating failures, and open line ends on long
lines.
Two step overvoltage protection (OV2PTOV) function can
be used to detect open line ends, normally then combined
with a directional reactive over-power function to supervise
the system voltage. When triggered, the function will cause
an alarm, switch in reactors, or switch out capacitor banks.
1MRK 505 379-BEN R
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M13789-3 v14
M13798-3 v17
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