Page 24
SE-330
Neutral-Grounding-Resistor
Monitor
Rev.
9-A-112913
17.3
(0.68)
36.6
(1.44)
29.9
(1.17)
43.5
(1
.71)
X1
X2
22.5
(0.89)
15.0
(0.59)
25.0
(0.98)
30.0
(1.18)
22.2 (0.87) DIA
LEGEND
PLATE
PILOT LIGHTS
14.9
(0.59)
36.6
(1.44)
29.9
(1.17)
43.5
(1
.71)
30.0 MINIMUM
(1.18)
40.0 MINIMUM
(1
.57)
PUSH BUTTON
MOUNTING DETAIL
NOTES:
1. TWO RED LED LIGHTS
24-120 VAC/DC, NOT POLARITY
SENSITIVE.
2. YELLOW PUSH BUTTON
3 A @ 240 VAC - A600,
0.5 A @ 125 VDC - Q600.
3. DIMENSIONS IN MILLIMETRES
(INCHES).
4. ----- INDICATES CLEARANCE
REQUIRED.
5. PANEL THICKNESS 1.0 TO 6.0
(0.04 TO 0.24).
6. NEMA 4X.
LEGEND PLATES
RESET
RESISTOR FAULT
GROUND FAULT
NOTE 4
FIGURE 19. RK-332 Remote Indication and Reset.
3.4 I
SOLATED
G
ROUND
C
ONNECTION
An isolated ground bed can prevent a ground potential
rise (GPR) from being transferred to remote equipment.
If the G terminals on the sensing resistor and the SE-330
are connected to an isolated ground, the SE-330 will be
exposed to the GPR. If the GPR is greater than the
terminal-block rating, the SE-330 must be isolated from
station ground and precautions must be taken with the
power supply and the trip contacts. See Technical Note
RG-1 “NGR Monitoring with Isolated Ground Beds” at
www.littelfuse.com/protectionrelays.
A configuration which allows an SE-330 to be
connected to station ground is shown in Fig. 20. The
SE-330 monitors the series combination of the NGR and
the two ground beds. This configuration is acceptable
provided the series resistance of the NGR and the ground
beds is within the NGR calibration range and ground-bed-
resistance changes remain within the trip range.
See Section 6.1.
NEUTRAL
NGR
N
ER-SERIES
SENSING
RESISTOR
R
G
STATION
TRIP CIRCUIT
22
23
STATION
CONTROL
SUPPLY
1
2
L1
L2/N
K1
R
6
G
7
SE-330
3
STATION GROUND BUS
STATION
GROUND BED
REMOTE GROUND
ISOLATED
GROUND BED
FIGURE 20. Simplified Isolated-Ground Connection.
