Instructional Literature
Page
152
Effective: May 2008
Instructions for the FP-6000 Protective Relay
For more information visit: www.eaton.com
IB02602004E
Nominal Current
The nominal primary current I
nom
, as measured by the FP-6000, is
established by the ratio of the selected current transformers. This
ratio must by set via the programming of the relay under
“System Config” in the Setting Main menu. These settings must
agree with the current transformers to which the relay is
connected. Therefore, I
nom
is established by the current
transformer ratio used and becomes the primary scale factor for
the trip functions and readouts.
Before proceeding with the curve explanation, it should be noted
that combining functional capabilities, such as inverse time
overcurrent, short delay and instantaneous, is a coordination
activity. The effects of one group of settings on another should be
understood in order to determine if the results are acceptable
under all foreseeable circumstances. This helps to avoid
unexpected operations or non-operations in the future. Keep in
mind that the FP-6000 operates its trip/alarm algorithms
simultaneously and independently. If any one of the algorithms
detects a trip condition, the FP-6000 will trip, even though the
user may expect one of the other trip curves (algorithms) to
prevail. For instance, if the Inverse Time Overcurrent calculation
results in a time which is less than the 50P-2 trip time, the
FP-6000 will trip; it will not cease ITOC evaluation within the
operative domain of the 50P-2 evaluation (see Figure 48.) The
shaded portion of the curve illustrates the ITOC value less than
the 50P-2 Delay time. For the FP-6000, the ITOC time will prevail.
The programmable logic may be configured to prevent tripping
in this region if desired.
Figure 48. Typical Curve with l2t Shape.
Inverse Time Overcurrent Protection
Inverse time overcurrent protection consists of a curve shape,
pickup setting, and an inverse time multiplier setting. The inverse
time overcurrent function offers 10 possible curve shape types as
previously described (see Figure 45 and Table 39). When
programming the FP-6000, this will be the first choice to make.
The curve shape and its effect on the characteristic curve will be
covered with the time multiplier explanations.
The pickup setting establishes the current level pickup at which
the relay’s inverse time overcurrent tripping function begins
timing. If, after a predetermined amount of time, the current
condition that started the timing process still exists, the inverse
time overcurrent function operates and the relay’s trip relay is
energized. Pickup settings can be adjusted from 0.10 to 4.00 times
I
nom
. Figure 47 graphically illustrates how the beginning of the
Thermal Inverse Time Overcurrent Pickup portion of the overall
curve can be moved horizontally on the time current grid by
means of the pickup settings. The Inverse Time Overcurrent
Pickup is represented by the dotted lines, while the rest of the
curve is represented by a solid line.
The Time Multiplier setting is used to select a predetermined
amount of time a sustained overload condition will be carried
before the breaker trips. For the Thermal Curves, a setting is
entered by determining the trip time needed at a 3 X I
nom
overcurrent for phase faults and I
nom
for ground faults. This value
is then divided by 5. For the ANSI and IEC curves, this represents
a pure multiplication of the curve as viewed in Section 8.3.2. A
wide range of time settings are available for curve shape
selection. As Time Multiplier settings are varied, the Time
Multiplier portion of the overall curve is moved vertically up or
down on the time current grid. This movement is also
independent of the other portions of the curve. Figure 49
graphically illustrates the vertical time line movement with an I
2
t
curve shape selection. Similar movement occurs for the
remaining curve shapes.
Figure 49. Typical Time Multiplier Adjustment (I
2
t Response).
Timed Overcurrent Protection
Two timed overcurrent functions are provided each for phase I
a
,
I
b
, I
c
, I
x
and I
r
. The pairs are: [50P1, 50P2], [50X1, 50X2] and [50R1,
50R2]. If desired they may be used for the traditional
Instantaneous Overcurrent function and the Short Time Delay
Overcurrent function. Instantaneous, is achieved by setting the
time delay to zero. In most cases the number 1 overcurrent
function is set as the instantaneous, and the number 2 as the
short delay. However, the setting ranges are identical for the two
sets of curves, and they may be set as the user desires.
Instantaneous Protection
Instantaneous (short circuit) protection reacts to high level fault
currents. The 50P pickup settings establish the current level at
which the FP-6000 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
independently in a horizontal direction. Figure 50 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.
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
n
) while the phase function is