Negative Sequence Current Protection - Eaton Cutler-Hammer FP 5000 Instruction Leaflet

IL17569C FP-5000
Page 8-6
Effective Date: 12/05
Instantaneous Protection
Instantaneous (short circuit) protection reacts to high level fault
currents. The 50P pickup settings establish the current level at which
the FP-5000 picks up on an instantaneous fault. An optional time
delay may be programmed for coordination purposes.
If an Instantaneous Setting other than "Disable" is selected, the
instantaneous portion of the overall curve can be moved indepen-
dently in a horizontal direction. Figure 8-9 graphically illustrates this
horizontal movement.
Ground Fault Protection
The ground fault protection function can be a composite of the ground:
1. Inverse time overcurrent curve shape pickup and time.
2. 50X-2 and 50R-2 (Short delay) pickup and time.
Figure 8-9. 50P (Instantaneous) Setting Adjustment
3. 50X-1 and 50R-1 (Instantaneous) pickup.
Its curve shape is independent of the phase curve. The inverse time
overcurrent time multiplier values for the ground function of the
thermal curves are for (1 x I ) while the phase function is (3 x I ).
n n
Movement of the pickup portion of the curve in a horizontal direction
and the time portion of the curve in a vertical direction is similar to
phase inverse time overcurrent, short delay and instantaneous
functions as previously described. Therefore, the ground fault curve
movement is not graphically illustrated. When programming ground
fault protection, keep in mind that if "Disable" is selected, the ground
fault protection is disabled.
Direction Control
Overcurrent protection elements, time inverse or instantaneous or
time delay, etc, can trip ina specified fault current direction. Whe
the trip direction is set to Both, the direction control takes no effect.
When it is set to Forward, a trip is only permitted in the Forward
o
direction where fault current lies within + 90 around the maximum
torque angle line. When it is set to Reverse, a trip is only permitted
o
in Reverse direction where fault current lies within + 90 around
the opposite of the maximum torque angle line. See Figures 5.1, 5.3
& 5.4 for detailed information.

8.3.4 Negative Sequence Current Protection (46)

The FP-5000 provides monitoring and protection based on the
percent of current unbalance or negative sequence. The presence of
negative sequence current identifies either a phase unbalance in the
voltage magnitude or reverse phase rotation condition. The positive
and negative sequence currents are calculated from the three phase
currents. The % unbalance is the ratio of negative sequence current to
positive sequence current (%Unbalance = I /I ). A current unbalance
2 1
pickup occurs when I /I exceeds the IUB % Unbalance setting, and
2 1
I or I magnitude exceeds the IUB Threshold setting. The Current
1 2
Unbalance trip is set when the pickup condition exists for the delay
time specified. The current unbalance pickup and trip is reset when
the positive sequence current drops below the IUB Threshold setting
or I /I drops below the IUB % Unbalance setting minus 1%. The
2 1
settings associated with voltage unbalance or negative sequence
voltage protection are listed in Table 8.2.
Page 8-6 For more information visit: www.eatonelectrical.com Effective Date: 12/05