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NGRM-ENC Enclosed Neutral-Grounding-Resistor Monitor Rev. 0-B-030515
3. INSTALLATION
3.1 TYPE 4X ENCLOSURE
The 455 x 340 x 175 mm polyester enclosure has a
hinged front panel with dual lockable latches. For wall
mounting, attach the included mounting brackets to the
back of the enclosure with the enclosed fasteners, and
prepare the mounting surface using the dimensions as
shown in Fig. 1.
All models ship with no predrilled cable entry. An
appropriate hole or holes must be made in the enclosure
for the installation of all conductors. Space is allowed at
the bottom for cable entry. See Figs. 4, 7, and 10. Use
appropriate cable-entry fittings.
3.2 CONNECTIONS TO THE NEUTRAL-GROUNDING-
RESISTOR AND CURRENT TRANSFORMER
For all models, connect NGRM-ENC terminal R to an
ER-series sensing resistor(1) terminal R. Follow SE-325 or
SE-330 manual guidelines for wire size selection. See
Figs. 2 and 3. All models connect to a current
transformer(1), which measures NGR current. The
sensing resistor and CT are typically located in the NGR
enclosure.
3.2.1 SE-325 MODELS
Connect the CT200 current transformer(1) secondary to
NGRM-ENC terminals CT1 and CT2. Connections are
not polarity sensitive. Follow SE-325 manual guidelines
for wire size selection. See Fig. 2.
3.2.2 SE-330 MODELS
For sensitive EFCT- or SE-CS30-series current
sensors(1), connect to NGRM-ENC terminals S and C.
For 5-A-secondary CT’s connect to terminals 5 and C. A
field-wiring change is required for 1-A-secondary CT
connections. See Fig. 3. CT connections are not polarity
sensitive. Follow SE-330 manual guidelines for wire size
selection.
3.3 SUPPLY VOLTAGE CONNECTION
Appropriate supply-voltage fusing is provided for all
models. Connect terminal GND to system ground.
3.3.1 SUPPLY BY FIELD CONNECTION
For models requiring field-supply-voltage connections,
connect line and neutral to NGRM-ENC terminals L and
N. See Figs. 2 and 3. SE-325 and SE-330 models require
a 120-Vac supply. Consult the appropriate product
manual for power requirements.
3.3.2 CONTROL POWER TRANSFORMER (CPT)
MODELS
Models equipped with a CPT are compatible with
480- and 600-V systems, and are factory-connected for a
600-V system. Field adjustment for a 480-V system is
required by moving the T1H3 connection on T1 to the H2
terminal of T1. Connect NGRM-ENC terminals ØA and
ØB to the 480- or 600-V bus using 14 to 6 AWG (2.08 to
13.3 mm2) wire. See Figs. 2 and 3.
3.4 PHASE-VOLTAGE INDICATION
For models equipped with phase-voltage and faulted-
phase indication, connect NGRM-ENC terminals ØA,
ØB, and ØC to the 480- or 600-V bus using 14 to 6 AWG
(2.08 to 13.3 mm2). See Figs. 2 and 3. These terminals
are shared by the CPT connections for models so
equipped.
3.5 RELAY-OUTPUT CONNECTIONS
For external alarm or trip indication and protection,
connect to SE-325 A-B relay output or SE-330 K1
relay output by connecting to NGRM-ENC terminals
301 and 302. A field-wiring change is required if a
supply-voltage connection is required to the relay
output(s) within the NGRM-ENC. Field wiring is
required if connection to SE-330 relay outputs K2, K3,
and K4 is required. See Figs. 2 and 3 and the
appropriate product manual.
NOTE:The SE-330 surface-mount options use relays K2
and K3 for panel-mounted ground-fault and resistor-fault
indication respectively.
3.6 NETWORK-COMMUNICATIONS CONNECTIONS
For SE-330 models equipped with a communications
option, connect directly to the SE-330 network
interface, referring to the appropriate product manual.
3.7 DIELECTRIC-STRENGTH TESTING
Remove the connections at the SE-325 and SE-330
L1 and L2 terminals, and remove the connection to the
EL3100 terminal 19 (if installed), before performing
dielectric-strength testing.
Ensure that all connections are reconnected and
securely fastened after any tests. See Figs. 2 and 3.
NOTES:
(1) Not included with the NGRM-ENC.
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