System Setup; Ac Inputs - GE UR Series Instruction Manual

5.3 SYSTEM SETUP

5.3 SYSTEM SETUP
a) CURRENT BANKS
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PATH: SETTINGS SYSTEM SETUP
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CURRENT BANK X1
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'X' = F, M, or U. 'F', 'M', and 'U' are module slot position letters. See also the section INTRODUCTION TO AC SOURCES.
Up to 6 banks of phase/ground CTs can be set.
These settings are critical for all features that have settings dependent on current measurements. When the relay is
ordered, the CT module must be specified to include a standard or sensitive ground input. As the phase CTs are connected
in Wye (star), the calculated phasor sum of the three phase currents (IA + IB + IC = Neutral Current = 3Io) is used as the
input for the neutral overcurrent elements. In addition, a zero sequence (core balance) CT which senses current in all of the
circuit primary conductors, or a CT in a neutral grounding conductor may also be used. For this configuration, the ground
CT primary rating must be entered. To detect low level ground fault currents, the sensitive ground input may be used. In this
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case, the sensitive ground CT primary rating must be entered. For more details on CT connections, refer to the HARD-
WARE chapter.
Enter the rated CT primary current values. For both 1000:5 and 1000:1 CTs, the entry would be 1000. For correct opera-
tion, the CT secondary rating must match the setting (which must also correspond to the specific CT connections used).
If CT inputs (banks of current) are to be summed as one source current, the following rule applies:
EXAMPLE:
SRC1 = F1 + F5 + U1
Where F1 , F5 , and U1 are banks of CTs with ratios of 500:1, 1000:1 and 800:1 respectively.
1 pu is the highest primary current. In this case, 1000 is entered and the secondary current from the 500:1 and 800:1 ratio
CTs will be adjusted to that which would be created by a 1000:1 CT before summation. If a protection element is set up to
act on SRC1 currents, then PKP level of 1 pu will operate on 1000 A primary.
The same rule will apply for sums of currents from CTs with different secondary taps (5 A and 1 A).
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AC INPUTS

CURRENT BANK X1
PHASE CT X1
PRIMARY:
PHASE CT X1
MESSAGE
SECONDARY: 1 A
GROUND CT X1
MESSAGE
PRIMARY:
GROUND CT X1
MESSAGE
SECONDARY: 1 A
L90 Line Differential Relay
Range: 1 to 65000 A in steps of 1
1 A
Range: 1 A, 5 A
Range: 1 to 65000 A in steps of 1
1 A
Range: 1 A, 5 A
5 SETTINGS
5.3.1 AC INPUTS
GE Power Management