Eaton Cutler-Hammer FP-5000 Instructions Manual page 82

Page 5-34
5.5.2. Protection Settings
The Protection Settings include all of the FP-5000 protective device
settings: 27, 46, 47, 50, 50BF, 51, 55A, 55D, 59, 81, zone interlock-
ing, and protection alarm settings. The setting descriptions below
will follow the order of the setting table. The FP-5000 may store
four complete sets of Protection settings. Table 5.1 lists only
settings for 1 setting group. Multiple copies of the Protection
section from the table may be needed for a complete record.
To navigate to the individual protection settings you must select
"Protection" from the Setting Main menu. If multiple setting groups
have been selected then you must select which protection setting
group you wish to set. You must now select the protection elements
that you want to set and enter down to the set point page. To change
an individual set point you must select the setting, press the enter
button and change the set point to the desired setting. You must
acknowledge the change by pressing the enter button again to return
to the previous level. If you press the "Previous" button then the
new setting will not be changed.
5.5.2.1 Phase Overcurrent Settings
51P PH TOC Curve:
This is the 51 device Phase Inverse Time Overcurrent Curve
Setting. The user selects the characteristic shape and the reset
characteristic of the TOC curve. The FP-5000 will have directional
capability in the future. The direction setting is fixed at Both.
There are three families of TOC curves to choose from:
Thermal: Flat, It, I t, and I
2
ANSI: Extremely Inverse, Very Inverse,
and Moderately Inverse
IEC: IEC-A, IEC-B, and IEC-C
The TOC reset is a time overcurrent memory feature and
has three setting choices:
Inst: Instantaneous reset: when the current drops
below the pickup setting, the TOC time resets
to zero within 2 cycles.
T Delay: Fixed time delay reset setting for the TOC curve.
The time delay is set to the TOC Reset T
setting of the System Configuration Settings. It
will hold the time ("percent travel"), at the last
value before the current drops below pickup,
for the set time (TOC Reset T). If the current
value goes above pickup before the reset time
has expired then the relay will begin to accu-
mulate time from its last value (percent travel).
"Percent Travel" refers to the percent of the
time delay that the timer has accumulated. The
time overcurrent time is dynamic. If the current
changes it will change its trip times to the new
value. Total trip time will be the time at which
the accumulator reaches 100%. For example,
if the current is at level 1 for 40% of the total
trip time based on level 1 current then the
accumulator will be at 40%. If the current now
changes to level 2 with a new trip time, then
the remaining trip time will be 60% of the new
trip time. So the total trip time will be 40% of
trip time t
1
was to drop below pickup for a time less
than the TOC Reset T in between level 1 and
t
4
plus 60% of trip time t . If the current
2
level 2 currents, then the total trip time will
include the time below pickup to the total trip
time calculated. This feature could be beneficial
to tripping for an arcing fault condition.
Calc: Calculated reset, which is defined by ANSI
C37.112. This setting represents the
electromechanical induction disk model and
best integrates in a system utilizing E/M relays.
T = (t x D) / [(I/I
reset r
constant and D is the time multiplier. See
Section 8 for more information.
Figure 5.1 provides a graphical representation of the three reset
characteristics. The rms current value is the bottom square wave
and assumes that the current level is either above or below the
pickup setting for a period of time. The three curves above the
current are the time values for the accumulator based on the three
reset characteristic settings. The Instantaneous reset appears as a
saw tooth and will not reach a trip time for this example. The
T Delay setting holds the time fixed at last value for the specified
reset time delay. This model will eventually accumulate enough time
and trip provided the current is not below the pickup setting for a
time greater than the reset time. The calculated reset option
emulates the electromechanical disc action and will slowly reset
over time to complete reset. This model will also trip in time.
Figure 5-1. Graphical Representation of
the TOC Reset T Setting
Time t , as shown, is less than the TOC Reset T time delay setting.
1
If t was greater than the TOC Reset T time delay setting, then the
1
51/w Time Delay Reset curve above would reset to zero.
IL17569
) – 1] where t is a curve
2
pu r
Effective June, 2001