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SE-107 Ground-Fault Ground-Check Monitor Rev. 5-C-050715
1. GENERAL
The SE-107 is a combination ground-fault and ground-
check monitor for resistance-grounded systems in non-
hazardous applications. The ground-fault circuit is
latching and the ground-check circuit is typically non-
latching. One output contact is provided for contactor
control or for undervoltage operation in a breaker trip
circuit.
Ground-fault current is sensed by a CT200-series
current transformer. A trip level of 0.5, 2.0, or 4.0 A is
switch selectable for use with a 5-, 15-, or 25-A
grounding resistor. Enhanced filtering eliminates false
ground-fault trips from adjustable-speed-drive harmonic
distortion. Trip time is adjustable from 0.1 to 2.0
seconds.
The fail-safe ground-check circuit is validated by an
end-of-line termination with a 5.6-volt Zener
characteristic. The Zener characteristic clamps induced
voltage and allows induced current to flow in the ground-
check loop. Consequently, induced-ac-withstand
capability, noise immunity, and open/short detection are
independent of current in the phase conductors.
Enhanced filtering prevents false ground-check validation
due to an active chopper condition. See
www.littelfuse.com/relayscontrols for Technical Note
GC-1.
CAUTION: The SE-107 is not a lock-out device. Follow
lock-out procedures for maintenance.
2. OPERATION
2.1 SETTINGS
2.1.1 GF TRIP TIME
Ground-fault trip time is adjustable from 0.1 to
2.0 seconds. Time-coordinated ground-fault protection
requires this setting to be longer than the trip time of
downstream ground-fault devices.
2.1.2 GF
The ground-fault-circuit trip level is 0.5, 2.0, or 4.0 A
when current is sensed with a CT200-series current
transformer. Since the ground-fault-circuit trip level
should not be greater than 20% of the grounding resistor
let-through current, these levels are appropriate for use
with 5-, 15-, or 25-A grounding resistors. For other
applications, the trip level of the ground-fault circuit is
0.25, 1.0, or 2.0% of the primary rating of the
5-A-secondary current transformer.
2.2 OUTPUT RELAY
The output relay operates in the undervoltage mode. It
is energized and its contact is closed when the ground-
check loop is valid and the ground-fault circuit is not
tripped. The undervoltage mode is referred to as fail-safe
because:
Undervoltage devices release if supply voltage fails.
Undervoltage ground-check circuits do not allow
cable couplers to be energized until the ground-check
loop is verified.
2.3 INDICATION AND RESET
The blue POWER LED indicates that the internal
power supply is on. The red GROUND FAULT LED
indicates a ground-fault trip and the green GROUND
CHECK LED indicates a valid ground-check loop. When
a ground-fault trip occurs, the SE-107 remains latched
until the reset switch is pressed or the supply voltage is
cycled. The ground-check circuit is non-latching and
does not require a reset. Terminals are provided for
remote indication and reset as shown in Fig. 1.
For the latching ground-check (Option L), the
GROUND CHECK LED is red and it indicates a latched
ground-check trip.
2.4 FUSING
The output contact is protected by fuse F1 (4.0 A, time
delay). The ground-check circuit is protected by fuse F2
(0.5 A, time delay).
3. INSTALLATION
3.1 SE-107
SE-107 outline and mounting details are shown in
Fig. 2. Typical connections are shown in Fig. 1. Connect
supply voltage to L1 and L2. For a 120-Vac supply,
connect supply neutral to L2. For a direct-current supply
(Option D), connect supply negative to L2. Connect
chassis-bonding terminal to ground.
Connect contact terminals A and B as required.
Faceplate LED’s are driven in series with remote-
indication LED’s. When a remote kit is not used,
terminals CI, +, and GI must be connected for the
faceplate LED’s to operate. These jumpers are installed
at the factory.
Connect terminal GC to the outgoing ground-check
conductor and connect terminal G to ground. To meet
electrical code requirements, do not jumper chassis-
bonding terminal to terminal G.
Install the upper terminal-block cover to prevent
inadvertent contact with line terminals.