Voltage Protection - Hitachi Relion 670 Series Product Manual

Phasor measurement unit RES670
Version 2.2
EF4PTOC also provides very fast and reliable faulty phase
identification for phase selective tripping and subsequent
reclosing during earth fault.
Four step directional negative phase sequence
overcurrent protection NS4PTOC
Four step directional negative phase sequence overcurrent
protection (NS4PTOC) has an inverse or definite time delay
independent for each step separately.
All IEC and ANSI time delayed characteristics are available
together with an optional user defined characteristic.
The directional function is voltage polarized.
NS4PTOC can be set directional or non-directional
independently for each of the steps.
NS4PTOC can be used as main protection for
unsymmetrical fault; phase-phase short circuits, phase-
phase-earth short circuits and single phase earth faults.
NS4PTOC can also be used to provide a system backup for
example, in the case of the primary protection being out of
service due to communication or voltage transformer circuit
failure.
Directional operation can be combined together with
corresponding communication logic in permissive or
blocking teleprotection scheme. The same logic as for
directional zero sequence current can be used. Current
reversal and weak-end infeed functionality are available.
Sensitive directional residual overcurrent and power
protection SDEPSDE
In isolated networks or in networks with high impedance
earthing, the earth fault current is significantly smaller than
the short circuit currents. In addition to this, the magnitude
of the fault current is almost independent on the fault
location in the network. The protection can be selected to
use either the residual current or residual power component
3U0·3I0·cos j, for operating quantity with maintained short
circuit capacity. There is also available one nondirectional
3I0 step and one 3U0 overvoltage tripping step.
No specific sensitive current input is needed. Sensitive
directional residual overcurrent and power protection
(SDEPSDE) can be set as low 0.25% of IBase.
Thermal overload protection, one time constant
LCPTTR/LFPTTR
The increasing utilization of the power system closer to the
thermal limits has generated a need of a thermal overload
protection for power lines.
A thermal overload will often not be detected by other
protection functions and the introduction of the thermal
overload protection can allow the protected circuit to
operate closer to the thermal limits.
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The three-phase current measuring protection has an I
characteristic with settable time constant and a thermal
memory. The temperature is displayed in either Celsius or
Fahrenheit, depending on whether the function used is
Thermal overload protection (LCPTTR) (Celsius) or
(LFPTTR) (Fahrenheit).
An alarm level gives early warning to allow operators to take
action well before the line is tripped.
Estimated time to trip before operation, and estimated time
to reclose after operation are presented.
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.

7. 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.
OV2PTOV has two voltage steps, each of them with inverse
or definite time delayed.
1MRK 511 410-BEN P
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SEMOD175421-4 v7
M13789-3 v14
M13798-3 v17
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