ABB REG650 - Monitored Data; Operation Principle

7.3.6 Monitored data
Table 68: LEXPDIS Monitored data
Name
Type Values (Range) Unit Description
XOHM REAL - Ohm Reactance in Primary
Ohms
XPERCENT REAL - % Reactance in percent of
Zbase
ROHM REAL - Ohm Resistance in Primary
Ohms
RPERCENT REAL - % Resistance in percent of
Zbase
7.3.7 Operation principle
The Loss of excitation (LEXPDIS) protection in the IED measures the apparent
positive sequence impedance seen out from the generator.
Measured mode Measured apparent impedance
Z
posseq
posseq
posseq
U
I
=
EQUATION1771 V1 EN (Equation 39)
There are three characteristics in LEXPDIS protection as shown in figure 71.
Naimly:
• Offset mho circle for Z1
• Offset mho circle for Z2
• Directional blinder
Section 7 1MRK 502 048-UEN A
Impedance protection
156
Technical manual