ABB RELION 670 Series Technical Manual page 713

1MRK 502 066-UUS B
It the generator is energized at stand still conditions, that is, when the voltage is zero, the
overcurrent function will operate after the short set delay if the generator current is larger than
the set value.
When the generator is started the overvoltage trip signal will be activated the set time delay after
the moment when the voltage has reached the set value. At this moment the blocking of the
overcurrent function is activated.
The delay of the undervoltage function will prevent false operation at short circuits in the external
power grid.
11.1.7.8 Logic diagram
The simplified internal logics, for CVGAPC function are shown in the following figures.
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ANSI05000169 V2 EN-US
Figure 377: Treatment of measured currents and voltages within IED for CVGAPC function
Figure 377
protection function
The following currents and voltages are inputs to the multipurpose protection function. They must
all be expressed in true power system (primary) Amperes and kilovolts.
1. Instantaneous values (samples) of currents & voltages from one three-phase current and one
three-phase voltage input.
2. Fundamental frequency phasors from one three-phase current and one three-phase voltage
input calculated by the pre-processing modules.
3. Sequence currents & voltages from one three-phase current and one three-phase voltage
input calculated by the pre-processing modules.
Technical manual
ADM
shows how internal treatment of measured currents is done for multipurpose
CVGAPC function
Current and voltage selection
settings
Selection of which current
and voltage shall be given to
the built-in protection
elements
Restraint current selection
Selected restraint current
Selection of restraint current
Section 11
Multipurpose protection
M13085-3 v5
IED
Selected current
Selected voltage
ANSI05000169_2_en.vsd
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