ABB RELION REX640 Technical Manual page 566

Protection functions
When
threshold (setting
the whole defined operate sector (see
unearthed networks.
Figure 325: Operating quantity = "Amplitude" and Directional mode = "Forward"
If the "Adaptive" or "Resistive" operating quantity is selected, the setting
operate current should be set to value:
[ ]
pu
[pu]
IRtot
p
It must be set to a value which is lower than the total resistive earth-fault current in
order to enable dependable operation.
Estimation of the total resistive earth-fault current of the network including the
parallel resistor of the coil and the network losses can be obtained from the
566
In compensated networks, where distributed compensation coils are
also used to compensate earth-fault current, setting
should be set to "Resistive". This enables secure and dependable
directional determination also in case of local overcompensation where
the earth-fault current produced by the healthy feeder can become
inductive.
Operating quantity is set to "Amplitude", the set minimum operate current
Min operate current ) is compared to the amplitude of
+90 deg.

Tilt angle
-90 deg.
< ⋅ p IRtot
Min operate current
Total resistive earth-fault current of the network corresponding to the resistive
current of the parallel resistor of the coil and the natural losses of the system
(typically in order of 1...5 % of the total capacitive earth-fault current of the
network).
security factor = 0.5...0.7
Figure 325
+45 deg.

0 deg.


1MRS759142 F
Operating quantity
). This selection can be used in
Technical Manual
1
I
in
o stab
Min
(Equation 99)
REX640