ABB Relion REC670 Applications Manual page 95

1MRK 511 358-UEN A
Table 12:
Operating
voltage
U>Trip
20 V
40 V
60 V
80 V
100 V
150 V
200 V
Table 13:
Operating
voltage
U>Trip
20 V
40 V
60 V
80 V
100 V
150 V
200 V
The current transformer saturation voltage must be at least 2 ˣ
operating margin. This must be checked after calculation of
When the R value has been selected and the
scheme
according to equation 15.
= ×
IP n IR
EQUATION1747 V1 EN-US
where:
n
IP
IR
Ires
ΣImag
It should be remembered that the vectorial sum of the currents must be used (IEDs, Metrosil
and resistor currents are resistive). The current measurement is insensitive to DC component
Application manual
1 A channels: input with minimum operating down to 40 mA
Stabilizing Operating
resistor R current level
ohms 1 A
500 0.040 A
1000 0.040 A
1500 0.040 A
2000 0.040 A
2500 0.040 A
3750 0.040 A
5000 0.040 A
5 A channels: input with minimum operating down to 100 mA
Stabilizing Operating
resistor R1 current level
ohms 5 A
200 0.100 A
400 0.100 A
600 0.100 A
800 0.100 A
1000 0.100 A
1500 0.100 A
2000 0.100 A
IP can be calculated. The IED sensitivity is decided by the total current in the circuit
å
+ +
( Ires lmag )
is the CT ratio
primary current at IED pickup,
IED pickup current (U>Trip/SeriesResistor)
is the current through the voltage limiter and
is the sum of the magnetizing currents from all CTs in the circuit (for example, 4 for
restricted earth fault protection, 2 for reactor differential protection, 3-5 for
autotransformer differential protection).
Stabilizing Operating
resistor R current level
ohms 1 A
-- --
-- --
600 0.100 A
800 0.100 A
1000 0.100 A
1500 0.100 A
2000 0.100 A
Stabilizing Operating
resistor R1 current level
ohms 5 A
100 0.200 A
200 0.200 A
300 0.200 A
400 0.200 A
500 0.200 A
750 0.200 A
1000 0.200 A
U>Trip .
U>Trip value has been set, the sensitivity of the
Differential protection
Stabilizing Operating
resistor R1 current level
ohms 5 A
-- --
100 0.400
150 0.400 A
200 0.400 A
250 0.400 A
375 0.400 A
500 0.400 A
U>Trip to have sufficient
(Equation 15)
Section 6
89