ABB Relion REG670, Technical Manual

Page: 278 / 1298

7.6.8 Technical data
Table 113: OOSPPAM technical data
Function Range or value Accuracy
Impedance reach (0.00 - 1000.00)% of Zbase ±2.0% of U
r
/(√3 ⋅ I
r
)
Rotor start angle (90.0 - 130.0) degrees ±5.0 degrees
Rotor trip angle (15.0 - 90.0) degrees ±5.0 degrees
Zone 1 and Zone 2 trip counters (1 - 20) -
7.7 Loss of excitation LEXPDIS
7.7.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Loss of excitation LEXPDIS
<
SYMBOL-MM V1 EN
40
7.7.2 Functionality
There are limits for the under-excited operation of a synchronous machine. A
reduction of the excitation current weakens the coupling between the rotor and the
stator. The machine may lose the synchronism and start to operate like an induction
machine. Then, the reactive power consumption will increase. Even if the machine
does not loose synchronism it may not be acceptable to operate in this state for a long
time. Reduction of excitation increases the generation of heat in the end region of the
synchronous machine. The local heating may damage the insulation of the stator
winding and the iron core.
To prevent damages to the generator it should be tripped when excitation is lost.
Section 7
1MRK502052-UEN B
Impedance protection
272
Technical manual