Startco Engineering Ltd.
Page 1
SE-701 Ground-Fault Monitor
Rev. 5
Pub. SE-701-M, December 14, 2006.
1. G
ENERAL
The SE-701 is a microprocessor-based ground-fault
monitor for resistance-grounded and solidly grounded
systems. Its output relay can operate in the fail-safe or
non-fail-safe mode for undervoltage or shunt-trip
applications. The normally open and normally closed
output contacts are isolated for use in independent control
circuits. Additional features include LED and
fluorescent-flag trip indication, autoreset or latching trips
with front-panel and remote reset, self test, 0- to 5-V
analog output, inputs for standard and sensitive
ground-fault current transformers, CT verification for
sensitive current transformers, digital selector switches,
switch-selectable algorithms for fixed-frequency or
variable-frequency applications, and an inhibit that can be
enabled to prevent the output relay from operating during
a high-current ground fault.
Ground-fault current is sensed by a standard CT with a
1-A or 5-A secondary, or by a sensitive CT with a
5-A-primary rating (EFCT-1, EFCT-2, or EFCT-26). The
trip level of the ground-fault circuit is switch selectable in
1% increments from 1 to 99% of the CT-primary rating.
Trip time is switch selectable with 10 settings from 0.05
to 2.5 seconds.
2. O
PERATION
2.1 C
ONFIGURATION
-S
WITCH
S
ETTINGS
See Fig. 1 for switch configuration.
2.1.1 R
ELAY
O
PERATING
M
ODE
The SE-701 has one output relay with isolated
normally open and normally closed contacts. Switch 1 is
used to set the operating mode of the output relay. In the
fail-safe mode, the output relay energizes when the
ground-fault circuit is not tripped. In the non-fail-safe
mode, the output relay energizes when a ground-fault trip
occurs.
2.1.2 I
NHIBIT
Switch 2 is used to select Class I or Class II operation.
In the INHIBIT OFF position, high-current inhibit is off
for Class I operation. In the INHIBIT ON position, high-
current inhibit is on for Class II operation. If high-current
inhibit is on and ground-fault current escalates above
eleven times the CT-primary rating before the ground-
fault circuit trips, the output relay will not operate until
ground-fault current falls below eight times the
CT-primary rating. This feature allows the overcurrent
protection to operate in applications where the ground-
fault current can be larger than the interrupting capacity
of the device tripped by the SE-701.
2.1.3 CT V
ERIFICATION
Switch 3 is used to enable CT verification with an
EFCT-series CT. In the CT VERIFY ON position, a trip
will occur if the CT is disconnected. The red TRIP LED
will flash to indicate a trip initiated by a CT fault. Switch
3 must be in the CT VERIFY OFF position when a 5-A-
or 1-A-secondary CT is used.
2.1.4 F
ILTER
S
ELECTION
Switch 4 is used to select the filtering algorithm for a
fixed-frequency (50/60 Hz) or variable-frequency
application. The fixed-frequency algorithm allows lower
trip levels to be used by rejecting harmonics that can
cause nuisance tripping. The fixed-frequency setting can
be used in an application on the line side of a variable-
frequency drive. The variable-frequency setting should
be used if the CT is located on the load side of a variable-
frequency drive.
2.1.5 A
UTORESET
Switch 5 is used to select autoreset or latching trips.
See Section 2.2.3.
2.2 F
RONT
-P
ANEL
C
ONTROLS
2.2.1 G
ROUND
-F
AULT
T
RIP
L
EVEL
The % CT PRIMARY selector switches are used to set
the ground-fault trip level as a percentage of the
CT-primary rating. Protection against arcing ground
faults in a solidly grounded system requires a ground-
fault CT that will not saturate below the operating value
of the overcurrent protection. For reliable ground-fault
detection, the ground-fault trip level must be substantially
below the prospective ground-fault current. To avoid
sympathetic tripping, the trip level must be above the
charging current of the largest feeder; and to eliminate
nuisance tripping, surge current must not saturate the CT.
For CT-selection assistance, see Technical Information
11.1 available at www.startco.ca.
2.2.2 G
ROUND
-F
AULT
T
RIP
T
IME
The TIME (s) selector switch is used to set the ground-
fault trip delay time for coordination with upstream and
downstream ground-fault devices. Coordination requires
the same trip level for all ground-fault devices in a system
and the trip time to progressively increase upstream. The
amount of equipment removed from the system will be a
minimum if the first ground-fault device to operate is the
one immediately upstream from the fault.
2.2.3 R
ESET
The reset circuit responds only to a momentary closure
so that a jammed or shorted switch will not prevent a trip.
The front-panel RESET switch is inoperative when the
remote-reset terminals (6 and 7) are shorted.
