Startco FPU-16 - Mode 9 - Percent Unbalance; MODES A, B, & C - AMMETERS; MODE D - PERCENT I; Emergency Thermal Reset

Startco Engineering Ltd. Page 17
FPU-16 Feeder Protection Unit Rev. 1
Pub. FPU-16-M, November, 1997 Downloaded from the Internet, see Disclaimer.
3.11 MODE 9 — PERCENT UNBALANCE
This mode is used to display percent current unbalance. The unbalance value
is calculated using equations 3.1 and 3.2. See Section 3.5.
The pre-trip current unbalance value can be recalled by pressing ENTER.
Range................................................... 0 to 100%
Resolution............................................. 1%
3.12 MODES A, b, and C — AMMETERS
These modes display the phase currents. Mode A is automatically displayed
when supply voltage is applied. For currents above 999 A, the last value digit is
replaced by E to indicate an extended range. To obtain the actual value,
multiply the reading by 100. For example, 30E is read as 3000 A.
If the 0.1 multiplier was used in Modes 7 and 8, multiply readings in Modes A, b,
and C by 10. Current as a percentage of rated current is displayed by pressing
RESET. Pre-trip ammeter values can be recalled by pressing ENTER.
Range................................................... 0 to 10 x I
n
Resolution............................................. 1 A for I < 1000 A
100 A for I  1000 A
Accuracy............................................... ± 0.3% Full Scale or
± 3% Reading
See Technical Specifications in Section 6 for metering accuracy vs ICT
interconnection cable length.
3.13
MODE d — PERCENT I
2
t / TIME-TO-RESET / EMERGENCY THERMAL RESET
This mode is used to display percent I
2
t which is a measure of used thermal
capacity. See Section 3.2. If a Mode-0 trip has occurred, Mode d is also used to
display time in minutes until a Mode-0 reset will be allowed. Reset time is a
function of the time constant and reset time is displayed when RESET is
pressed.
EMERGENCY THERMAL RESET will set I
2
t to 0% and reset Mode 0. For
EMERGENCY THERMAL RESET:
— Defeat program-change lockout by connecting FPU-16 terminals 20 and
21,
— select Mode d, and
— press RESET and ENTER simultaneously.