1–12
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
SPECIFICATIONS
CHAPTER 1: INTRODUCTION
NEUTRAL DIRECTIONAL (67N)
Directionality: ....................................................... Forward and reverse
Polarizing:............................................................... Voltage, Current, Dual
Polarizing Voltage:.............................................. - V
0
calculated using phase voltages (VTs must be
connected in “Wye”)
-3V
0
measured from Vaux input (3V
0
provided by an
external broken delta connection).
Polarizing Current:.............................................. I
G
MTA:........................................................................... From 0
º
to 359
º
in steps of 1°
Angle Accuracy: .................................................. ±4
º
Operational Delay:............................................. 20 to 30 ms
NOTE
NOTE:
The selection of the “D” option from “350 OTHER OPTIONS” in the Order Code table, will
enable the Neutral Directional element with voltage polarizing 3V
0
measured from the
Vaux voltage input.
The selection of “P”, “R”, or “W” option from “350 OTHER OPTIONS” in the Order Code table,
will enable the Neutral Directional elements with voltage polarizing V
0
computed from the
measured phase voltage inputs.
The ground polarizing current, I
G
, is available for selection in both cases.
THERMAL OVERLOAD (49)
Current:.................................................................... RMS current - max (Ia, Ib, Ic)
Pickup Accuracy: ................................................ per current inputs
Timing Accuracy:................................................ See graph below
Figure 1-5:
The graph shows the trip time error with respect to the ratio of cable load and thermal
model pickup setting. With a smaller I/Ipkp ratio, the time error tends to be higher, as
accumulated through the logarithmic formula, the measurement error, and the time of
measurement. For higher I/Ipkp ratios, the time to trip is substantially more accurate. Each
point on the graph represents a trip time error, with the I/Ipkp ratio kept constant during
the test.
PHASE/AUXILIARY/POSITIVE SEQUENCE UNDERVOLTAGE (27P, 27X, 27_1)
Minimum Voltage: .............................................. Programmable from 0.00 to 1.25 x VT in steps of 0.01
Pickup Level: ......................................................... 0.00 to 1.25 x VT in steps of 0.01
Dropout Level:...................................................... 102% of pickup (pickup > 0.1 x VT)
0.02 x VT (pickup < 0.1 x VT)
Curve: ....................................................................... Definite Time, Inverse Time
Time Delay: ........................................................... 0.00 to 600.00 s in steps of 0.01
Operate Time: ...................................................... Time delay ±30 ms @ 60 Hz (V < 0.85 x PKP)
Time delay ±40 ms @ 50 Hz (V < 0.85 x PKP)
Time Delay Accuracy:...................................... ±3% of expected time, or 1 cycle, whichever is greater
Level Accuracy: ................................................... Per voltage input
