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2 CALCULATION OF SETTINGS
2.3 PROTECTION SETTINGS
2.3.7 OVERCURRNT
601: 50 - Phase Instantaneous Overcurrent
The 50 function can be used in many applications to provide high speed, direct tripping for heavy close-in
faults. To use the phase instantaneous overcurrent trip function, set 50 = YES, otherwise set 50 = NO. See
Protection Settings 602 and 603 for further discussion on use of 50 function. Also, Protection Setting 201:
Z2PHASE must be set to YES.
2
602: 50_DIRCNL - Directional Control Of 50
The 50 function can be set to be either directional or nondirectional. Directionality is obtained through the use
of the Zone 2 phase distance functions. Protection Setting 201 must be set to Z2PHASE = YES to make the 50
function directional.
If 50 is made directional, the setting to be made on the function is based on the maximum fault current for a
fault at the remote end of the line. When 50 is made non-directional, then the setting is based on the maximum
fault current for a fault at either end of the line. If the maximum fault current for a fault at either end of the line is
approximately the same, then it is proposed that the 50 function be made non-directional.
603: 50PICKUP - 50 Pickup Setting
50 provides direct tripping for multi-phase faults, and it operates on the highest of the three delta currents,
IA-IB, IB-IC, or IC-IA. This permits 50 to have the same response for all multi-phase faults at the same location.
If 50PICKUP is non-directional, then it should be set at least 25% greater than the maximum delta three-phase
fault current for a fault at either terminal of the line. If 50PICKUP is directional, then it should be set at least
25% greater than the maximum delta three-phase fault current for a fault at the remote terminal of the line. The
setting is calculated on the basis of the delta current which for a three phase fault is equal to the square root of
three times the phase current.
604: 50PICKUPFF - 50 Pickup During Fuse Failure
If 50 is made directional and potential is lost to the relay, then directional control will be lost and the 50 function
will not be able to provide any protection. To overcome this drawback, a second setting (50PICKUPFF) can be
made on the 50 function to provide some backup during a loss of potential. A 50PICKUPFF setting must
always be made and it must always be set at least 25% greater than the maximum delta three-phase fault cur-
rent for a fault at either terminal of the line.
605: 50G - Ground Instantaneous Overcurrent
The 50G function can be used in many applications to provide high speed, direct tripping for heavy close-in
faults. To use the ground instantaneous overcurrent trip function, set 50G = YES, otherwise set 50G = NO. See
Protection Settings 606 and 607 for further discussion on use of 50G function.
606: 50G_DIRDNL - Directional Control Of 50G
The 50G function can be set to be either directional or nondirectional. Directionality is obtained through the use
of the negative-sequence directional functions by requiring operation of the NT (forward looking) function and
non-operation of the NB (reverse looking) function.
If 50G is made directional, the setting to be made on the function is based on the maximum fault current for a
fault at the remote end of the line. When 50G is made nondirectional, the setting is based on the maximum
fault current for a fault at either end of the line. If the maximum fault current for a fault at either end of the line is
approximately the same, then it is proposed that the 50 function be made nondirectional.
GE Power Management
LPS-D Line Protection System
2-
27
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