Setting Guideline - ABB REL670 2.2 IEC Applications Manual

Section 9
Current protection
9.7.3
506
continues to increase to the trip value TripTemp, the protection initiates trip of the
protected line.

Setting guideline

The parameters for the Thermal overload protection, one time constant, Celsius/
Fahrenheit LCPTTR/LFPTTR are set via the local HMI or PCM600.
The following settings can be done for the thermal overload protection.
Operation: Off/On
GlobalBaseSel is used to select a GBASVAL function for reference of base values,
primary current (IBase), primary voltage (UBase) and primary power (SBase).
Imult: Enter the number of lines in case the protection function is applied on
multiple parallel lines sharing one CT.
IRef: Reference, steady state current, given in % of IBase that will give a steady
state (end) temperature rise TRef. It is suggested to set this current to the maximum
steady state current allowed for the line/cable under emergency operation (a few
hours per year).
TRef: Reference temperature rise (end temperature) corresponding to the steady
state current IRef. From cable manuals current values with corresponding
conductor temperature are often given. These values are given for conditions such
as earth temperature, ambient air temperature, way of laying of cable and earth
thermal resistivity. From manuals for overhead conductor temperatures and
corresponding current is given.
Tau: The thermal time constant of the protected circuit given in minutes. Please
refer to manufacturers manuals for details.
TripTemp: Temperature value for trip of the protected circuit. For cables, a
maximum allowed conductor temperature is often stated to be 90°C (194°F). For
overhead lines, the critical temperature for aluminium conductor is about 90 -
100°C (194-212°F). For a copper conductor a normal figure is 70°C (158°F).
AlarmTemp: Temperature level for alarm of the protected circuit. ALARM signal
can be used as a warning before the circuit is tripped. Therefore the setting shall be
lower than the trip level. It shall at the same time be higher than the maximum
conductor temperature at normal operation. For cables this level is often given to
65°C (149°F). Similar values are stated for overhead lines. A suitable setting can
be about 15°C (59°F) below the trip value.
ReclTemp: Temperature where lockout signal LOCKOUT from the protection is
released. When the thermal overload protection trips, a lock-out signal is activated.
This signal is intended to block switch in of the protected circuit as long as the
conductor temperature is high. The signal is released when the estimated
1MRK 506 369-UEN B
Line distance protection REL670 2.2 IEC
Application manual
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