SE-701 Ground-Fault Monitor
Page ii
Rev. 10-C-072414
T
ABLE OF
C
ONTENTS
S
ECTION
1
P
AGE
L
IST OF
F
IGURES
F
IGURE
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P
AGE
Introduction
......................................................... 1
1.1 General .................................................................. 1
1.2 Current-Sensor Selection ...................................... 1
2
Operation
............................................................. 1
2.1 Configuration-Switch Settings .............................. 1
2.1.1 Relay Operating Mode ............................... 1
2.1.2 Trip Inhibit ................................................. 1
2.1.3 CT Verification .......................................... 1
2.1.4 Filter Selection ........................................... 1
2.1.5 Reset Mode ................................................ 1
2.2 Front-Panel Controls ............................................. 2
2.2.1 Ground-Fault Trip Level............................ 2
2.2.2 Ground-Fault Trip Time ............................ 2
2.2.3 Reset .......................................................... 2
2.2.4 Test ............................................................ 2
2.3 Front-Panel Indication .......................................... 2
2.3.1 Power ......................................................... 2
2.3.2 Trip ............................................................ 2
2.3.3 Trip Inhibit ................................................. 2
2.4 Analog Output....................................................... 2
2.5 Self Diagnostics .................................................... 2
3
Installation
........................................................... 3
4
SE-701 Compatibility
.......................................... 6
5
Technical Specifications
................................... 14
6
Ordering Information
....................................... 16
7
Warranty
........................................................... 17
8
Ground-Fault Performance Test
..................... 18
Appendix A SE-701 Revision History
......................... 20
SE-701 Outline and Mounting Details ...................4
Typical Connection Diagrams................................5
Typical Three-Phase-Starter Connection ...............5
EFCT-1 Outline and Mounting Details ..................7
EFCT-2 Outline and Mounting Details ..................8
EFCT-26 and SE-CS30-26
Outline and Mounting Details ..................................9
SE-CS30-70 Current Sensor .................................... 10
SE-CS30-4, -5, and -8 Current Sensors ................... 11
PMA-55 Panel-Mount Adapter ............................12
PMA-60 Panel-Mount Adapter ............................13
PGA-0500 Analog Percent Current Meter ...........14
Ground-Fault-Test Circuits ..................................18
L
IST OF
T
ABLES
T
ABLE
1
2
P
AGE
Trip-Features Comparison .....................................6
Ground-Fault-Test Record ...................................19
D
ISCLAIMER
Specifications are subject to change without notice.
Littelfuse Startco is not liable for contingent or
consequential damages, or for expenses sustained as a
result of incorrect application, incorrect adjustment, or a
malfunction.
SE-701 Ground-Fault Monitor
1. I
NTRODUCTION
1.1 G
ENERAL
The SE-701 is a microprocessor-based ground-fault
monitor for resistance-grounded and solidly grounded
systems. It is uniquely suited for use on systems with
significant harmonic content. Its output relay can operate
in the fail-safe or non-fail-safe mode for undervoltage or
shunt-trip applications. The SE-701 has one output relay
with isolated normally open and normally closed contacts
for use in independent control circuits. Additional
features include LED trip, power, and inhibit indication,
autoreset or latching trips with front-panel and remote
reset, trip memory, test button, self diagnostics, 0- to 5-V
analog output, inputs for ground-fault current sensors, CT
verification for EFCT-series current sensors, 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 current transformer.
Core-balance zero sequence current sensors (CT's) are most
commonly used. Bus bar or toroid style CT's can also be
used on the neutral to ground connection. See Fig. 2 in
Technical Note CT-08 available at www.littelfuse.com. The
trip level of the ground-fault circuit is switch selectable in
1% increments from 1 to 99% of the CT rating.
1.2 C
URRENT-
S
ENSOR
S
ELECTION
An SE-701 has inputs for 1-, 5-A, and 50-mA-secondary
CT’s. Choose a CT that provides the required ground-fault-
trip range.
For ground-fault detection, the ground-fault trip level
must be substantially below the prospective ground-fault
current. In a solidly grounded system, prospective ground-
fault current is similar to phase-fault current. In a resistance-
grounded system, prospective ground-fault current is
defined by the neutral-grounding-resistor let-through-current
rating.
In a solidly grounded system, protection against arcing
ground faults requires a ground-fault CT that will detect
low-level fault current but not saturate up to the operating
value of the system overcurrent protection. In general,
immunity to saturation is proportional to CT mass.
To eliminate nuisance tripping, surge current must not
saturate the CT.
For low-level ground-fault protection use an EFCT-1,
EFCT-2, or EFCT-26 earth-fault CT with a 5-A-primary
rating. However, protection at this level might not be
possible because of high surge current or prospective
ground-fault current.
For CT-selection assistance, see Technical Note CT-01
available at www.littelfuse.com/relayscontrols.
Page 1
Rev. 10-C-072414
2. O
PERATION
2.1 C
ONFIGURATION
-S
WITCH
S
ETTINGS
See Fig. 1.
2.1.1 R
ELAY
O
PERATING
M
ODE
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 fail-
safe mode, non-volatile memory retains the trip status of
the SE-701. If tripped, and the supply voltage is cycled,
the SE-701 will remain tripped, with the trip relay
de-energized and the TRIP LED on, until reset.
In the non-fail-safe mode, the output relay energizes
when a ground-fault trip occurs. In the non-fail-safe
mode, trip status is not retained in non-volatile memory.
2.1.2 T
RIP
I
NHIBIT
Switch 2 is used to select Class I or Class II operation.
In the OFF position, high-current trip inhibit is off for
Class I operation. In the ON position, high-current trip
inhibit is on for Class II operation. If high-current trip
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 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 ON position, a trip will occur if
the CT is disconnected. Switch 3 must be in the OFF
position when an EFCT-series CT is not used and must be
in the ON position when an EFCT 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 setting uses a
DFT filter that allows lower trip levels to be used by
rejecting harmonics that can cause nuisance tripping.
The VARIABLE FREQUENCY setting uses a peak-
detection algorithm with a wider bandwidth for fault
detection in variable-frequency drive applications.
2.1.5 R
ESET
M
ODE
Switch 5 is used to select autoreset or latching trips.
See Section 2.2.3.
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