Z3Distance - GE ALPS Instruction Manual

2.3 PROTECTION SETTINGS
• PUTT Scheme: Operation of this scheme is dependent on the Zone 1 ground distance functions keying the transmitter
for ground faults. As such, the increased sensitivity provided by the IPT function is of no significant benefit. The follow-
ing setting is proposed:
Z2GRDCHAR = MHO
• Blocking, Hybrid, POTT1 and POTT2 Schemes: If high resistance ground faults are of concern, the following setting
is proposed:
2
Z2GRDCHAR = MHOGDOC
206: Z2GRDREACH - Z2 Ground Distance Function Reach
See the Z2PHREACH phase distance function reach setting (Protection Setting 202); the same philosophy applies.
207: Z2GCHARANG - Z2 Ground Distance Function Characteristic Angle
Z2GCHARANG is adjustable from 80° to 155° and determines the shape of the Zone 2 ground characteristics – circle or
lens. Set Z2GCHARANG equal to Z2PCHARANG as determined earlier.
208: Z2TIMERS - Z2 Timers
Z2TIMERS can be set to YES or NO and determines if the independent Zone 2 timers associated with the Zone 2 phase
and ground distance functions are to be used. If time-delayed backup protection is required, set Z2TIMERS = YES, other-
wise, set Z2TIMERS = NO.
209: Z2P_TIME - Z2 Phase Timer
Z2P_TIME can be set over the range of 0.1 to 3.0 seconds and establishes the time delay that the Zone 2 phase functions
can be picked up before tripping is initiated. If the Zone 2 phase distance functions are set to provide traditional Zone 2 pro-
tection then set Z2P_TIME with the normal Zone 2 time delay. If the Zone 2 functions are used to provide Zone 3 tripping as
described under the Z2PHREACH setting, the set Z3P_TIME with the normal Zone 3 time delay. If Z2TIMERS is set to NO,
then this setting is irrelevant and can be ignored.
210: Z2G_TIME - Z2 Ground Timer (Revision B models only)
Z2G_TIME can be set over the range of 0.1 to 3.0 seconds and establishes the time delay that the Zone 2 phase functions
can be picked up before tripping is initiated. If the Zone 2 phase distance functions are set to provide traditional Zone 2 pro-
tection then set Z2G_TIME with the normal Zone 2 time delay. If the Zone 2 functions are to be used to provide Zone 3 trip-
ping as described earlier under the Z2GRDREACH setting, then set Z2G_TIME with the normal Zone 3 time delay. If
Z2TIMERS is set to NO, then this setting is irrelevant, and can be ignored.
211: Z2RGREACH - Zone 2 Resistive Ground Reach (Revision B models only)
Z2RGREACH can be set from 0.01 to 100.00 Ω for a 5 A rated relay (0.05 to 500 Ω for a 1 A rated relay). It determines the
position of the right resistive blinder for the ground distance quadrilateral characteristic to provide coverage for resistive
ground faults. If Zone 3 is also set to Quad mode, this setting should be calculated at 0.8 or less of the Zone 3 Resistive
Ground Reach (Protection Setting 310: Z3RGREACH). If Zone 3 is not set to Quad mode, the setting should be calculated
as 0.8 (if "tent" characteristics are used) or less (0.6 to 0.7 if "tent" characteristics are not used) of the positive-sequence
resistance seen by the relay under maximum load conditions and unity power factor. Also, to maintain zone accuracy, it is
recommended that the resistive reach is not greater than 10 times the Ground Distance Reach (Protection Setting 206:
Z2GRDREACH) for this zone.
301: Z3PHASE - Select Zone 3 Phase
Z3PHASE can be set to either YES or NO. When Zone 3 is used as part of a Step Distance scheme, and Zone 3 phase dis-
tance functions are required then set Z3PHASE = YES. If Zone 3 is not used required, set Z3PHASE = NO.
2-16 ALPS Advanced Line Protection System
2 CALCULATION OF SETTINGS

2.3.4 Z3DISTANCE

GE Power Management