Startco Engineering Ltd.
Page 6
SE-325 Neutral-Grounding-Resistor Monitor
Rev. 8
Pub. SE-325-M, May 6, 2008.
3.3 S
ENSING
R
ESISTOR
Outline and mounting details for ER-600VC, ER-5KV,
ER-15KV, and ER-25KV sensing resistors are shown in
Figs. 4, 5, 6, and 7. Locate the NGR and the sensing
resistor near the transformer or generator. When located
outdoors, a sensing resistor must be installed in a suitable
enclosure. Ground sensing-resistor terminal G. Pass the
sensing-resistor-to-neutral conductor and the NGR-to-
neutral conductor through the ground-fault-CT window as
shown in Fig. 1. Separately connect sensing-resistor
terminal N and the NGR to the neutral to include neutral
connections in the monitored loop. If a ground fault in the
sensing-resistor conductor is unlikely, a minimal loss of
protection will result if it does not pass through the ground-
fault-CT window.
C
AUTION:
Voltage at terminal N rises to line-to-neutral
voltage when a ground fault occurs. The same clearances
are required for sensing resistors as for NGR's.
N
OTE:
The neutral-to-sensing-resistor connection is not
a neutral conductor as defined in Canadian Electrical
Code Section 10-1108 and National Electrical Code
Section 250.36(B). It is not required to be 8 AWG or
larger. Since current through this conductor is always
less than 150 mA, a 14 AWG conductor insulated to the
system voltage is more than sufficient.
MOUNTING DETAIL
105.0
8.0
89.0
8.0
40.0
19.0
10.5
10.5
(4.13)
(0.31)
(3.50)
(0.31)
(1.57)
(0.75)
(0.41)
(0.41)
N O T E 3
SIDE
41.5
22.2
(1.63)
(0.87)
FRONT
NOTES:
1.
2.
3.
4.
5.
DIMENSIONS IN MILLIMETRES (INCHES).
TERMINAL-BLOCK SCREWS: 6-32 x 0.25.
MOUNTING SCREWS: M4 OR 8-32.
ON REVISION 2 UNITS ENCLOSURE IS ELECTRICALLY CONNECTED
TO TERMINAL G THROUGH JUMPER FROM TERMINAL G TO
SCREW.
THIS CONNECTION MAY BE REMOVED FOR DIELECTRIC STRENGTH
TESTING. ENSURE THAT THE JUMPER IS INSTALLED AFTER TESTING.
ON REVISION 1 UNITS,
SCREW IS NOT PRESENT AND ENCLOSURE
IS ELECTRICALLY CONNECTED TO TERMINAL G.
4.5 (0.18) DIA
C'BORE 10.0 (0.39) DIA
3.2 (0.13) DEEP
40.0
105.0
(1.57)
(4.13)
RATINGS:
MAXIMUM VOLTAGE . 600 Vac
MAXIMUM CURRENT . 30 mA
RESISTANCE . . . . . . . 20 k
THERMAL:
420 Vac . . . . . . . . . . CONTINUOUS
600 Vac . . . . . . . . . . 6 MINUTES ON,
60 MINUTES OFF
W
N
R
G
E R - 6 0 0 V C
SENSING RESISTOR
20 K
600 VAC MAX
W
STARTCO
MADE IN SASKATOON, CANADA
E N G I N E E R I N G L T D .
FIGURE 4. ER-600VC Sensing Resistor.