Setting Guidelines - ABB REC650 Applications Manual

Section 6
Current protection
6.10.3
6.11
6.11.1
138
unsymmetrical check on the line where the IED connected will give alarm or trip at
detecting broken conductors.

Setting guidelines

GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
Broken conductor check BRCPTOC (46) must be set to detect open phase/s (series faults)
with different loads on the line. BRCPTOC (46) must at the same time be set to not operate
for maximum asymmetry which can exist due to, for example, not transposed power lines.
All settings are in primary values or percentage.
Set minimum operating level per phase Pickup_PH to typically 10-20% of rated current.
Set the unsymmetrical current, which is relation between the difference of the minimum
and maximum phase currents to the maximum phase current to typical Pickup_ub = 50%.
Note that it must be set to avoid problem with asymmetry under minimum
operating conditions.
Set the time delay tOper = 5 - 60 seconds and reset time tReset = 0.010 - 60.000 seconds.
Directional over-/under-power protection GOPPDOP/
GUPPDUP (32/37)
Application
The task of a generator in a power plant is to convert mechanical energy available as a
torque on a rotating shaft to electric energy.
Sometimes, the mechanical power from a prime mover may decrease so much that it does
not cover bearing losses and ventilation losses. Then, the synchronous generator becomes
a synchronous motor and starts to take electric power from the rest of the power system.
This operating state, where individual synchronous machines operate as motors, implies
no risk for the machine itself. If the generator under consideration is very large and if it
consumes lots of electric power, it may be desirable to disconnect it to ease the task for the
rest of the power system.
1MRK 511 286-UUS A
Application manual