© 2018 Littelfuse Fresh Water Pumping
Littelfuse.com/Pump-Protection
20
Single-Phase Pump Protection
Programmable and Low-Range Programmable
Description
The 77C-KW/HP is a programmable solid-state power monitor/
overload relay that protects single-phase, 100-240VAC,
2-800 amp pumps (external CTs are required for 91-800 amps)
from dry-well, dead-head, jammed impeller and other voltage
and current conditions. The LR version is designed for easier
installation at a lower 1-9 full load amps.
This Littelfuse 77C-KW/HP is programmable to your specific
pumping application and provides a digital display of real-
time data of the pump’s operation and fault conditions. The
programmability allows the user to set trip points, trip delays
and restart delays, to include protection from successive power
outages and short-cycling/rapid-cycling caused by other motor
controls, and delays for motor cool-down time and dry-well
recovery time.
The 77C-KW/HP can be programmed and monitored through
network communications, as well as hooked to a remote
display unit to program and monitor the pump protection from
an alternate location, or outside the electrical panel to avoid
potential arc flash (arc flash is a serious hazard that can happen
when opening an electrical panel).
Specifications
Functional Specifications
Programmable Operating
Points
LV-Low Voltage Threshold
85V - HV Setting
HV-High Voltage Threshold
LV Setting - 264V
MULT-# of Conductors or
CT Ratio (xxx:5)
77C-KW/HP: 1-10 Conductors or 100-800 Ratio
77C-LR-KW/HP: 1 or 2 conductors
OC-Overcurrent Threshold
(20-100A) / MULT or 80-120% of CT Primary
LP-Low Power Threshold
See PWS below or 0=off
TC-Overcurrent Trip Class
5, J5, 10, J10, 15, J15, 20, J20, 30, J30 or
Lin (linear)
PWS-Power Setpoint Range
(1,2,3,4)(5,6,7,8) (settings
within ranges are adjusted
in LP settings)
1
=0.01-0.99kw
5
=0.01-1.33hp
2
=1.00-9.95kw
6
=1.34-13.3hp
3
=10.0-99.5kw
7
=13.4-133hp
4
=100-650kw
8
=134-871hp
RD1-Rapid-Cycle Timer
0, 2-500 Seconds
RD2-Restart Delay after all
faults except underload
(motor cool down timer)
2-500 Minutes/Seconds
RD3-Restart Delay after
undercurrent (dry-well
recovery timer)
2-500 Minutes/Seconds
#RU-Number of restarts
after underload
0, 1, 2, 3, 4, A (automatic)
#RO-Number of restarts
after overload
0, 1, 2, 3, 4, A (automatic)
ADDR-RS485 Address
A01-A99
OPT1-To set linear OC trip
delay when TC is set to Lin
2-60 seconds
OPT2-To set RD2 & RD3 in
either seconds or minutes
0, 1, 2, 3
MODEL
DESCRIPTION
77C-KW/HP
Programmable Pump Protection
77C-LR-KW/HP
Low-Range Programmable Pump Protection
Ordering Information
77C-KW/HP / 77C-LR-KW/HP
Programmable Power Monitor/Overload Relay
