Voltage Protection; Frequency Protection - ABB Relion 670 Series Product Manual

Phasor measurement unit RES670
Pre-configured
Product version: 1.2
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.
Thermal overload protection, one time constant
LPTTR
The increasing utilizing of the power system
closer to the thermal limits has generated a need
of a thermal overload protection also 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.
The three-phase current measuring protection
2
has an I t characteristic with settable time
constant and a thermal memory.
An alarm level gives early warning to allow
operators to take action well before the line is
tripped.

5. 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.
12
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 etc.
OV2PTOV has two voltage steps, each of them
with inverse or definite time delayed.
OV2PTOV has an extremely high reset ratio to
allow settings close to system service voltage.

6. Frequency protection

Underfrequency protection SAPTUF
Underfrequency occurs as a result of lack of
generation in the network.
Underfrequency protection SAPTUF is used for
load shedding systems, remedial action schemes,
gas turbine startup and so on.
SAPTUF is provided with an undervoltage
blocking.
The operation is based on positive sequence
voltage measurement and requires two phase-
phase or three phase-neutral voltages to be
connected. For information about how to connect
analog inputs, refer to Application manual/IED
application/Analog inputs/Setting guidelines
Overfrequency protection SAPTOF
Overfrequency protection function SAPTOF is
applicable in all situations, where reliable
detection of high fundamental power system
frequency is needed.
Overfrequency occurs at sudden load drops or
shunt faults in the power network. Close to the
generating plant, generator governor problems
can also cause over frequency.
SAPTOF is used mainly for generation shedding
and remedial action schemes. It is also used as a
frequency stage initiating load restoring.
SAPTOF is provided with an undervoltage
blocking.
1MRK 511 266-BEN -
ABB