Monitored Data - ABB Relion Technical Manual

Section 6
Differential protection
Name Values (Range)
ZSCurrSubtrW1 Disabled
Enabled
ZSCurrSubtrW2 Disabled
Enabled
ZSCurrSubtrW3 Disabled
Enabled
6.1.2.5
6.1.3
90
Unit Step
- -
- -
- -

Monitored data

Table 28: T3WPDIF (87T) Monitored data
Name Type
IDMAG_A REAL
IDMAG_B REAL
IDMAG_C REAL
IBIAS REAL
IDMAG_NS REAL
Operation principle
The task of the power transformer differential protection is to determine whether a fault
is within the protected zone, or outside of the protected zone. The protected zone is limited
by the position of current transformers (see figure 31), and in principle can include more
objects than just a transformer. If the fault is found to be internal, the faulty power
transformer must be quickly disconnected from the system.
The main CTs are normally supposed to be Wye connected and can be grounded in any
direction (that is, either "ToObject" or "FromObject"). Internally the IED will always
measure the currents on all sides of the power transformer with the same reference
direction towards the power transformer windings as shown in figure 31.
Default Description
Enabled Enable zero sequence subtraction for W1 side,
Off/On
Enabled Enable zero sequence subtraction for W2 side,
Off/On
Enabled Enable zero sequence subtraction for W3 side,
Off/On
Values (Range) Unit
- A
- A
- A
- A
- A
1MRK 502 048-UUS A
Description
Magnitude of fundamental
frequency differential current,
phase A
Magnitude of fundamental
frequency differential current,
phase B
Magnitude of fundamental
frequency differential current,
phase C
Magnitude of the bias current,
which is common to all phases
Magnitude of the negative
sequence differential current
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