7.2.7 Technical data
Table 61: ZGCPDIS technical data
Function
Range or value Accuracy
Number of zones 3 -
Forward positive sequence impedance (0.005-3000.000) Ω/
phase
± 2.0% static accuracy
Conditions:
• Voltage range:
(0.1-1.1) x U
r
• Current range: (0.5-30)
x I
r
• Angle: at 85 degrees
Reverse positive sequence impedance (0.005-3000.000) Ω/
phase
-
Angle for positive sequence impedance, (10-90) degrees -
Timers (0.000-60.000) s ± 0.5% ± 10 ms
Operate time 25 ms typically -
Reset ratio 105% typically -
7.3 Loss of excitation LEXPDIS
7.3.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Loss of excitation LEXPDIS
SYMBOL-MM V1 EN
40
7.3.2 Functionality
There are limits for the low excitation 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 becomes too
low.
1MRK 502 048-UEN A Section 7
Impedance protection
153
Technical manual
To Next Page
Loading...
