Littelfuse Startco SE-325 User manual

SE-325 MANUAL
NEUTRAL-GROUNDING-RESISTOR MONITOR
MAY 6, 2008
REVISION 10
F1
RESET
POWER
GROUND
FAULT
GF TRIP
TIME (s)
RESISTOR
FAULT
RES TRIP
LEVEL (VAC)
CT1 CT2 AB
RIGISW
L1
R
L2
G
STARTCO
ENGINEERING LTD.
NGR MONITOR
SE-325
MODE RESGF
20 400
200
0.1 2.0
1.0
4.0 A
2.0 A
0.5 A
SH
UV 20K
Copyright ©2008 by Startco Engineering Ltd.
All rights reserved.
Publication: SE-325-M
Document: S95-C325-00000
Printed in Canada.

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Startco Engineering Ltd. Page i
SE-325 Neutral-Grounding-Resistor Monitor Rev. 6
Pub. SE-325-M, May 6, 2008.
TABLE OF CONTENTS
PAGE
Table of Contents .................................................................... i
List of Figures.......................................................................... i
List of Tables ........................................................................... i
1. General ......................................................................... 1
1.1 Modern Resistance-Grounded Systems ....................... 1
1.2 SE-325 NGR Monitoring.............................................. 1
2. Operation...................................................................... 1
2.1 Settings ..........................................................................1
2.1.1 GF Trip Time................................................... 1
2.1.2 GF .................................................................... 1
2.1.3 Mode ................................................................ 2
2.1.4 RES .................................................................. 2
2.1.5 RES Trip Level................................................ 2
2.2 Indication and Reset......................................................2
2.3 Fusing ............................................................................ 2
3. Installation.................................................................... 3
3.1 SE-325 .......................................................................... 3
3.2 Ground-Fault CT........................................................... 5
3.3 Sensing Resistor ............................................................ 6
3.4 Isolated-Ground Connection....................................... 12
3.5 Overhead Lines ...........................................................12
3.6 Remote Operation .......................................................12
3.7 Ground-Fault Testing.................................................. 12
4. Technical Specifications ...........................................12
4.1 SE-325 ........................................................................12
4.2 Sensing Resistors......................................................... 13
4.3 Current Transformer....................................................13
5. Ordering Information............................................... 14
6. Warranty.................................................................... 14
7. Test Procedures .........................................................15
7.1 Ground-Fault Performance Test ................................. 15
7.2 Resistor-Fault Tests.....................................................16
7.2.1 Open Test ..........................................................16
7.2.2 Voltage Test ......................................................16
7.3 Sensing-Resistor Test.................................................. 16
LIST OF FIGURES
FIGURE PAGE
1 Typical Application ...................................................... 3
2 SE-325 Outline and Mounting Details......................... 4
3 Current Transformers.................................................... 5
4 ER-600VC Sensing Resistor ........................................ 6
5 ER-5KV Sensing Resistor ............................................ 7
6 ER-15KV Sensing Resistor .......................................... 8
7 ER-25KV Sensing Resistor .......................................... 9
8 RK-302 Remote Indication and Reset ....................... 10
9 RK-325 Remote Indication-and-Reset Assembly ..... 10
10 RK-325I Remote Indication Assembly...................... 11
11 RK-13 Relay Interface Module .................................. 11
12 Ground-Fault-Test Circuits......................................... 15
LIST OF TABLES
TABLE PAGE
1 Settings For Typical Systems ....................................... 2
2 Ground-Fault-Test Record.......................................... 15
DISCLAIMER
Specifications are subject to change without notice. Startco
Engineering Ltd. is not liable for contingent or consequential
damages, or for expenses sustained as a result of incorrect
application, incorrect adjustment, or a malfunction.

Startco Engineering Ltd. Page ii
SE-325 Neutral-Grounding-Resistor Monitor Rev. 0
Pub. SE-325-M, May 6, 2008.
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Startco Engineering Ltd. Page 1
SE-325 Neutral-Grounding-Resistor Monitor Rev. 8
Pub. SE-325-M, May 6, 2008.
1. GENERAL
1.1 MODERN RESISTANCE-GROUNDED SYSTEMS
A high-resistance-grounded system uses a neutral-
grounding resistor (NGR) with a low let-through current
to limit ground-fault current. High-resistance grounding
is gaining popularity because a ground-fault flash hazard
exists in low-resistance- or solidly grounded systems and
a ground-fault can result in substantial point-of-fault
damage. High-resistance grounding eliminates these
problems and modern ground-fault protection operates
reliably at these levels. Furthermore, the probability of an
arc-flash incident is significantly reduced in a high-
resistance-grounded system.
NGR selection depends on system charging current and
whether the system is an alarm-only or a tripping system.
Alarm-only systems are usually restricted to system
voltages up to 5 kV with NGR let-through currents of 5 A
or less. Occasionally, alarm-only systems up to 15 kV
and up to 10 A are used; however, they are not common
because a ground fault on such a system tends to escalate
to a phase-to-phase fault before the ground fault can be
located and cleared.
System charging current is the capacitive current that
flows to ground when a bolted ground fault occurs. This
current can be calculated or measured. For small systems,
the magnitude of charging current is typically ½ A per
1,000 kVA on low-voltage systems and 1 A per
1,000 kVA on medium-voltage systems.
In an alarm-only system or in a tripping system without
selective coordination, choose an NGR with a let-through
current larger than the system charging current and set
the pick-up current of ground-fault devices at or below
50% of the NGR let-through current.
In a tripping system with selective coordination, use
ground-fault devices with a definite-time characteristic to
achieve time coordination. Use the same pick-up current
for all ground-fault devices—this value must be larger
than the charging current of the largest feeder. Select an
NGR with a let-through current between five and ten
times the pick-up current of the ground-fault devices.
Do not use a grounding transformer with a low-voltage
resistor:
•The combined cost of a transformer and a low-
voltage resistor is more than the cost of a resistor
rated for line-to-neutral voltage.
•A transformer saturated by a ground fault through a
rectifier can make ground-fault protection
inoperative.
•Transformer inrush current up to twelve times rated
current can cause a ground-fault voltage larger than
expected.
•A parallel transformer winding makes it difficult to
monitor NGR continuity.
•A transformer can provide the inductance necessary
to cause ferroresonance if the NGR opens.
Following these guidelines will reduce the flash
hazard, reduce point-of-fault damage, achieve reliable
ground-fault protection, and ensure a stable system not
subject to ferroresonance.
1.2 SE-325 NGR MONITORING
The SE-325 is a neutral-grounding-resistor monitor for
resistance-grounded systems up to 25 kVac. It measures
current in a transformer or generator neutral, neutral-to-
ground voltage, and continuity of the neutral-grounding
resistor. The SE-325 coordinates these three measurements
to detect a failed NGR or a ground fault and provides one
output contact for shunt or undervoltage operation in a
main-breaker trip circuit. Trips are latched and indicated by
LED’s.
Ground-fault current is sensed by a CT200 window-type
current transformer. Either CT input can be grounded to
meet electrical codes. A trip level of 0.5, 2.0, or 4.0 A is
switch selectable for use with a 5-, 15-, or 25-A grounding
resistor. Trip time is adjustable from 0.1 to 2.0 seconds.
Neutral-to-ground voltage and continuity of the neutral-
grounding resistor are continuously measured through an
ER-series external sensing resistor connected to the neutral.
A resistor fault will be detected if ground-fault current is not
detected and neutral-to-ground voltage exceeds the trip-level
setting, or if NGR resistance exceeds the trip resistance. A
resistor-fault hold-off circuit prevents nuisance trips in
alarm-only systems.
For additional information on neutral-grounding-resistor
monitoring, see “Monitoring Neutral-Grounding Resistors”
at www.startco.ca.
2. OPERATION
2.1 SETTINGS
2.1.1 GF TRIP TIME
Ground-fault trip time is adjustable from 0.1 to 2.0
seconds. Time-coordinated ground-fault protection requires
this setting to be longer than the trip times of downstream
ground-fault devices.
For the extended trip-time option, trip time is adjustable
from 0.1 to 5.0 seconds.
2.1.2 GF
The ground-fault-circuit trip level is 0.5, 2.0, or 4.0 A
when current is sensed with a CT200 current transformer.
Since the ground-fault-circuit trip level should not be greater
than 20% of the grounding resistor let-through current, these
levels are appropriate for use with 5-, 15-, or 25-A
grounding resistors. See Table 1. For other applications, the
trip level of the ground-fault circuit is 0.25, 1.0, or 2.0% of
the primary rating of the 5-A-secondary current transformer.

Startco Engineering Ltd. Page 2
SE-325 Neutral-Grounding-Resistor Monitor Rev. 8
Pub. SE-325-M, May 6, 2008.
2.1.3 MODE
In the shunt-trip mode (SH), the output relay energizes
and its contact closes if a resistor-fault or ground-fault trip
occurs. The shunt-trip mode is not fail-safe because shunt-
trip devices do not operate if supply voltage fails.
In the undervoltage mode (UV), the output relay
energizes and its contact closes if the resistor-fault and
ground-fault circuits are not tripped. The undervoltage
mode is referred to as fail-safe because undervoltage devices
release if supply voltage fails.
2.1.4 RES
This switch setting must correspond to the resistance of
the external sensing resistor. For the ER-600VC and
ER-5KV, select 20K. For the ER-15KV and ER-25KV,
select 100K.
2.1.5 RES TRIP LEVEL
Neutral-to-ground trip voltage is adjustable from 20 to
400 Vac with a 20-kΩsensing resistor, and 100 to
2,000 Vac with a 100-kΩsensing resistor. To prevent false
resistor-fault trips, the RES TRIP LEVEL should be set
higher than the voltage across the neutral-grounding resistor
when neutral-to-ground current is equal to the operating
value of the ground-fault circuit. Typical values for 5-, 15-,
and 25-A tripping systems are shown in Table 1. For others
systems, refer to the NGR Monitor Set-Point Assistant at
www.startco.ca.
2.2 INDICATION AND RESET
The green POWER LED indicates that the internal power
supply is on. Red LED's indicate ground-fault and resistor-
fault trips. When a trip occurs, the SE-325 remains latched
until the reset switch is pressed or supply voltage is cycled.
Terminals are provided for remote indication and reset as
shown in Fig. 1.
For the non-latching option, the SE-325 resets when the
fault clears.
2.3 FUSING
The output contact is protected by fuse F1 (4.0 A, time
delay).
TABLE 1. SETTINGS FOR TYPICAL SYSTEMS
System
Voltage
Neutral-Grounding
Resistor
Sensing
Resistor
Ground-Fault
Trip Level ResTrip Level
(Volts)
Let Through
(Amperes)
Resistance
(Ohms)
Model Resistance
(Ohms) (Amperes) (Volts)
480
600
2,400
4,160
480
600
2,400
4,160
7,200
14,400
7,200
14,400
25,000
5
5
5
5
15
15
15
15
15
15
25
25
25
55
69
277
480
18
23
92
160
277
554
166
332
577
ER-600VC
ER-600VC
ER-5KV
ER-5KV
ER-600VC
ER-600VC
ER-5KV
ER-5KV
ER-15KV
ER-15KV
ER-15KV
ER-15KV
ER-25KV
20,000
20,000
20,000
20,000
20,000
20,000
20,000
20,000
100,000
100,000
100,000
100,000
100,000
0.5
0.5
0.5
0.5
2.0
2.0
2.0
2.0
2.0
2.0
4.0
4.0
4.0
30
40
140
240
40
50
190
320
600
1,100
700
1,400
2,000

Startco Engineering Ltd. Page 3
SE-325 Neutral-Grounding-Resistor Monitor Rev. 9
Pub. SE-325-M, May 6, 2008.
3. INSTALLATION
3.1 SE-325
SE-325 outline and mounting details are shown in
Fig. 2. Typical connections are shown in Fig. 1. Connect
supply voltage to L1 and L2. For a 120-Vac supply,
connect supply neutral to L2. For a direct-current supply,
connect supply negative to L2. Connect chassis-bonding
terminal to ground.
Connect contact terminals A and B as required.
Face-plate LED's are driven in series with remote-
indication LED's. When remote-indication LED’s are not
used, terminals GI, +, and RI must be connected for the
face-plate LED’s to operate. These jumpers are installed
at the factory.
Install the upper terminal-block cover to prevent
inadvertent contact with line terminals.
N
R
G
ER-600VC
SENSING RESISTOR
20 K
600 VAC MAX
W
STARTCO
ENGINEERING LTD.
MADE IN SASKATOON, CANADA
600 V
4160 V
SUPPLY
NEUTRAL
GROUNDING
RESISTOR
CT200
GROUND-FAULT CT
UV
120 VAC
LN
LOAD
RESISTOR-FAULT
INDICATOR
GROUND-FAULT
INDICATOR
RESET SWITCH
REMOTE INDICATION AND RESET
RED
RED
F1
RESET
POWER
GROUND
FAULT
GF TRIP
TIME (s)
RESISTOR
FAULT
RES TRIP
LEVEL (VAC)
CT1 CT2 AB
RIGISW
L1
R
L2
G
STARTCO
ENGINEERING LTD.
NGR MONITOR
SE-325
MODE RESGF
20 400
200
0.1 2.0
1.0
4.0 A
2.0 A
0.5 A
SH
UV 20K
RIGISW R G
STARTCO
ENGINEERING LTD.
NGR MONITOR
SE-325
ER
R
S
1
R
S
2
C
G
I
G
R
I
+
S
WK1 K2
SW CI/GI + GI/RI
TB1
RESISTOR-FAULT
INDICATOR
GROUND-FAULT
INDICATOR
RESET SWITCH
RED
RED
RK-13 CONNECTION WITH REMOTE INDICATION AND RESET
ALTERNATE
RESET CIRCUIT
24-120 Vac/Vdc
RK-13 CONNECTION WITHOUT REMOTE INDICATION OR RESET
K1 K2 RI
+
GI
SW
RIGISW R G
STARTCO
ENGINEERING LTD.
NGR MONITOR
SE-325
RI
GI
SW
ER
R
S
1
R
S
2
C
G
I
G
R
I
+
S
WK1 K2
SW CI/GI + GI/RI
TB1
K1 K2
RIGISW R G
STARTCO
ENGINEERING LTD.
NGR MONITOR
SE-325
ER
NOTES:
1. ALTERNATE SENSING-RESISTOR TERMINAL-N CONNECTION,
THE NEUTRAL CONNECTION IS NOT MONITORED.
2. K1 CLOSES ON GROUND-FAULT TRIP.
3. K2 CLOSES ON RESISTOR-FAULT TRIP.
4. VOLTAGE BETWEEN ER TERMINALS R AND G
LIMITED TO 100 V BY INTERNAL CLAMP.
CAUTION: DO NOT USE K1 OR K2 IN A TRIP CIRCUIT.
NOTE 1
NOTES 2 & 3
NOTE 4
FIGURE 1. Typical Application.

Startco Engineering Ltd. Page 4
SE-325 Neutral-Grounding-Resistor Monitor Rev. 7
Pub. SE-325-M, May 6, 2008.
NOTES:
1.
2.
3.
4.
5.
DIMENSIONS IN MILLIMETRES (INCHES).
TERMINAL-BLOCK SCREWS: 6-32 x 0.25.
MOUNTING SCREWS: M4 OR 8-32.
SHOWN WITH TERMINAL-BLOCK COVER REMOVED.
MINIMUM CLEARANCE FOR FUSE REMOVAL.
109.0
(4.29)
(3.50)
(5.50)
(5.90)
88.9
139.7
150.0
4.8 (0.19) DIA
100.0
(3.93)
(3.06)
77.8
F1
RESET
POWER
GROUND
FAULT
GF TRIP
TIME (s)
RESISTOR
FAULT
RES TRIP
LEVEL (VAC)
CT1 CT2 AB
RIGISW
L1
R
L2
G
STARTCO
ENGINEERING LTD.
NGR MONITOR
SE-325
MODE RESGF
20 400
200
0.1 2.0
1.0
4.0 A
2.0 A
0.5 A
SH
UV 20K
43.5
(1.71)
NOTE 5
NOTE 4
FIGURE 2. SE-325 Outline and Mounting Details.

Startco Engineering Ltd. Page 5
SE-325 Neutral-Grounding-Resistor Monitor Rev. 8
Pub. SE-325-M, May 6, 2008.
3.2 GROUND-FAULT CT
Outline and mounting details for CT200 and CT200L
current transformers are shown in Fig. 3. Ground-fault-CT
connections and the typical ground-fault-CT location are
shown in Fig. 1.
Connect the secondary of the ground-fault CT to SE-325
terminals CT1 and CT2. The CT connection to the SE-325
is not polarity sensitive. Ground one side of the CT
secondary. For electrically noisy environments or lead
lengths in excess of 10 m (30 ft), use shielded, twisted-pair
cable.
D
A
E
B
FRONT
9.4
(0.37)
F
BOTTOM
B
C
TAP M4 OR 8-32
22.2
(0.87)
44.5
(1.75)
MOUNTING DETAIL
SIDE
WHITE
BLACK
X1 X2
44.5 MAX
(1.75)
NOTES:
1. DIMENSIONS IN
MILLIMETRES (INCHES).
2. MOUNTING SCREWS:
M4 OR 8-32.
PART
NUMBER
CT200
CT200L
ABCD EF
55.9 (2.20)
88.9 (3.50)
120.7 (4.75)
154.0 (6.06)
101.6 (4.00)
133.4 (5.25)
98.3 (3.87)
139.7 (5.50)
108.0 (4.25)
144.5 (5.69)
5.6 (0.22)
7.1 (0.28)
DIMENSIONS
FIGURE 3. Current Transformers.

Startco Engineering Ltd. Page 6
SE-325 Neutral-Grounding-Resistor Monitor Rev. 8
Pub. SE-325-M, May 6, 2008.
3.3 SENSING RESISTOR
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.
CAUTION: 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.
NOTE: 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 10.510.5
(4.13)
(0.31)
(3.50)
(0.31)
(1.57)
(0.75) (0.41)(0.41)
NOTE 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 .......20k
THERMAL:
420Vac ..........CONTINUOUS
600Vac ..........6MINUTES ON,
60 MINUTES OFF
W
N
R
G
ER-600VC
SENSING RESISTOR
20 K
600 VAC MAX
W
STARTCO
MADE IN SASKATOON, CANADA
ENGINEERING LTD.
FIGURE 4. ER-600VC Sensing Resistor.

Startco Engineering Ltd. Page 7
SE-325 Neutral-Grounding-Resistor Monitor Rev. 7
Pub. SE-325-M, May 6, 2008.
355.6
254.0
127.0
457.0
50.7 (14.00)
(10.00)
(5.00)
(18.00)
(2.00)
MINIMUM DISTANCE
TO ADJACENT OBJECTS
MOUNTING DETAIL
NOTE 3
NOTES:
1.
2.
3.
4.
DIMENSIONS IN MILLIMETRES (INCHES).
TERMINAL-BLOCK SCREWS: 6-32 x 0.25.
MOUNTING SCREWS: M6 OR 0.25-20.
THIS DEVICE CAN DISSIPATE
300 WATTS. TO MINIMIZE SURFACE
TEMPERATURES FOR SYSTEMS
ALLOWED TO OPERATE
CONTINUOUSLY WITH A GROUND
FAULT, MOUNT VERTICALLY WITH
R & G TERMINALS DOWN.
ON REVISION 2 UNITS BASE 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 REV 0 & 1 UNITS SCREW IS NOT
PRESENT AND BASE IS ELECTRICALLY
CONNECTED TO TERMINAL G.
316.0
GR
188.0
(12.44)
(7.40)
FRONT VIEWSIDE VIEW
0.25-20 UNC STUD
VOLTAGE ON THIS SURFACE RISES
TO LINE-TO-NEUTRAL VOLTAGE
WHEN A GROUND FAULT OCCURS
N
CAUTION
HIGH VOLTAGE
STARTCO
ENGINEERING LTD.
MADE IN SASKATOON, CANADA
ER-5KV
SENSING RESISTOR
20 K
2500 VAC MAX
W
381.0
21.0
12.0
105.0
7.9
52.5
(15.00)
(0.83)
(0.47)
(4.13)
(0.31)
(2.07)
NEUTRAL CONNECTION
ALTERNATE NEUTRAL CONNECTION
TOP VIEW
0.25-20 UNC
THREADED
INSERT
10-32 THREADED
INSERT
RATINGS:
MAXIMUM VOLTAGE . 2,500 Vac
MAXIMUM CURRENT . 125 mA
RESISTANCE .......20k
THERMAL ..........CONTINUOUS
W
5.
MINIMUM CLEARANCE FROM BASE
254.0 (10.00)
NOTES 5 & 6
NOTE 2
6.
FIGURE 5. ER-5KV Sensing Resistor.

Startco Engineering Ltd. Page 8
SE-325 Neutral-Grounding-Resistor Monitor Rev. 7
Pub. SE-325-M, May 6, 2008.
N
STARTCO
ENGINEERING LTD.
MADE IN SASKATOON, CANADA
VOLTAGE AT TERMINAL N RISES
TO LINE-TO-NEUTRAL VOLTAGE
WHEN A GROUND FAULT OCCURS
CAUTION
HIGH VOLTAGE
ER-15KV
SENSING RESISTOR
100 K
8400 VAC MAX
1MINUTEMAX
W
422.0
(16.61)
144.0
215.0
90.0
280.0
100.0
90.0
(5.67)
(8.46)
(3.53)
(11.00)
(3.94)
(3.53)
FRONT
MOUNTING DETAIL
SIDE
NOTES:
TOP
444.0
(17.50)
(14.37)(1.56) (1.56)
365.039.5 39.5
MINIMUM DISTANCE
TO ADJACENT OBJECTS
NOTE 3
1. DIMENSIONS IN MILLIMETRES
(INCHES).
2. TERMINAL-BLOCK SCREWS:
6-32 x 0.25.
3. MOUNTING SCREWS:
M6 OR 0.25-20.
4. USE LIQUID-TIGHT GLAND FOR
TERMINAL-BLOCK-ENCLOSURE
CABLE ENTRY.
132.0
(5.20)
RATINGS:
MAXIMUM VOLTAGE . . 8,400 Vac
MAXIMUM CURRENT . 84 mA
RESISTANCE .......100k
THERMAL ..........1MINUTE ON,
120 MINUTES
OFF
W
R
G
MINIMUM CLEARANCE FROM BASE
305.0 (12.00)
0.25-20 BINDING HEAD
20.5
(0.81)
NOTE 2
FIGURE 6. ER-15KV Sensing Resistor.

Startco Engineering Ltd. Page 9
SE-325 Neutral-Grounding-Resistor Monitor Rev. 7
Pub. SE-325-M, May 6, 2008.
800
60 340.0340.0
534
217 100.0
(31.5)
(2.4) (13.38)(13.38)
(21.0)
(8.5) (3.94)
MOUNTING DETAIL
NOTES:
1. DIMENSIONS IN
MILLIMETRES (INCHES).
2. TERMINAL-BLOCK SCREWS:
6-32 x 0.25.
3. MOUNTING SCREWS:
M6 OR 0.25-20.
4. USE LIQUID-TIGHT GLAND
FOR TERMINAL-BLOCK-
ENCLOSURE CABLE ENTRY.
NOTE 3
MINIMUM DISTANCE
TO ADJACENT OBJECTS
320
(12.6)
FRONT SIDE
N
STARTCO
ENGINEERING LTD.
MADE IN SASKATOON, CANADA
VOLTAGE AT TERMINAL N RISES
TO LINE-TO-NEUTRAL VOLTAGE
WHEN A GROUND FAULT OCCURS
CAUTION
HIGH VOLTAGE
ER-25KV
SENSING RESISTOR
100 K
14,400 VAC MAX
1MINUTEMAX
W
780
(5.67)
20.5
(30.7)
(0.81)
TOP
RATINGS:
MAXIMUM VOLTAGE . 14,400 Vac
MAXIMUM CURRENT . 144 mA
RESISTANCE .......100k
THERMAL ..........1MINUTE ON,
120 MINUTES OFF
W
0.25-20 BINDING HEAD
144.0
R
G
MINIMUM CLEARANCE FROM BASE
508.0 (20.00)
NOTE 2
FIGURE 7. ER-25KV Sensing Resistor.

Startco Engineering Ltd. Page 10
SE-325 Neutral-Grounding-Resistor Monitor Rev. 7
Pub. SE-325-M, May 6, 2008.
NOTES:
1. DIMENSIONS IN MILLIMETRES
(INCHES).
2. INDICATES CLEARANCE
REQUIRED.
3. PANEL THICKNESS 1.0 TO 6.0
(0.04 TO 0.24).
4. NEMA 4X.
LEGEND PLATE
30.0
(1.18)
LEGEND
PLATE
22.2 (0.87) DIA
25.0
(0.98)
15.0
(0.59)
22.5
(0.89)
MOUNTING DETAIL
30.0 MINIMUM
(1.18)
40.0 MINIMUM
(1.57)
LED PILOT LIGHTS
36.6
(1.44)
17.3
(0.68)
29.9
(1.17)
43.5
(1.71)
PUSH BUTTON
36.6
(1.44)
14.9
(0.59)
29.9
(1.17)
43.5
(1.71)
FIGURE 8. RK-302 Remote Indication and Reset
NOTES:
1. DIMENSIONS IN MILLIMETRES (INCHES).
2. NEMA 1.
FRONT VIEW
RESISTOR FAULTRESISTOR FAULT
GROUND FAULTGROUND FAULT
RESET
STARTCO
ENGINEERING LTD.
RK-325
60.0
(2.36)
44.5
(1.75)
(0.30)
(0.40)
7.7
10.0
96.0
(3.78)
76.0
(3.00)
(0.875)
22.25
28.58
(1.125)
1.25"
CONDUIT
KNOCKOUT
1.70" DIA
3.8 (0.15)
DIA
MOUNTING DETAIL
OUTLINE
SIDE VIEW
CI/RI
+
GI
SW
30.0
(1.18)
25.0
(0.98)
FIGURE 9. RK-325 Remote Indication-and-Reset Assembly.

Startco Engineering Ltd. Page 11
SE-325 Neutral-Grounding-Resistor Monitor Rev. 6
Pub. SE-325-M, May 6, 2008.
60.0
(2.36)
44.5
(1.75)
(0.30)
(0.40)
7.7
10.0
96.0
(3.78)
76.0
(3.00)
(0.875)
22.25
28.58
(1.125)
1.25"
CONDUIT
KNOCKOUT
1.70" DIA
3.8 (0.15)
DIA
MOUNTING DETAIL
SIDE VIEW FRONT VIEW
RESISTOR FAULTRESISTOR FAULT
GROUND FAULTGROUND FAULT
STARTCO
ENGINEERING LTD.
RK-325I
30.0
(1.18)
25.0
(0.98)
CI/RI
+
GI
OUTLINE
NOTES:
1. DIMENSIONS IN MILLIMETRES (INCHES).
2. NEMA 1.
FIGURE 10. RK-325I Remote Indication Assembly.
60.2
31.0
47.5
21.0
(2.37)
(1.22)
(1.87)
(0.83)
R
S
1
R
S
2
C
G
I
G
R
I
+
S
WK1 K2
R
S
1
R
S
2
C
G
I
G
R
I
+
S
WK1 K2
SW CI/GI +
GI/RI
TB1
INSTALLATION INSTRUCTIONS:
1. REMOVE FOUR LEFTMOST LOWER TERMINAL BLOCK SCREWS.
2. PLACE RK-13 ON TERMINAL BLOCK AND REPLACE SCREWS.
3. MAKE REQUIRED CONNECTIONS TO TERMINAL BLOCK TB1.
SIDE VIEW
RK-13 SHOWN MOUNTED ON SE-105/SE-107/SE-325
NOTES:
1. DIMENSIONS IN MILLIMETRES (INCHES).
FIGURE 11. RK-13 Relay Interface Module.

Startco Engineering Ltd. Page 12
SE-325 Neutral-Grounding-Resistor Monitor Rev. 1
Pub. SE-325-M, May 6, 2008.
3.4 ISOLATED-GROUND CONNECTION
The SE-325 is intended for use in installations where the
NGR is connected to local ground. Some installations
require the NGR to be isolated from local ground. See
Technical Information 3.1 “NGR Monitoring with Isolated
Ground Beds” at www.startco.ca.
3.5 OVERHEAD LINES
In overhead-line applications, atmospheric conditions can
cause false resistor-fault trips. The “S” option or an SE-330
NGR Monitor is recommended for these applications.
3.6 REMOTE OPERATION
Terminals SW, GI, +, and RI are provided for remote
LED indication and remote reset as shown in Fig. 1.
Remote LED's are driven in series with the front-panel
LED’s.
Remove factory-installed jumpers from terminals GI, +,
and RI, and connect a remote kit as shown in Fig. 1.
Optional remote kits are shown in Figs. 8, 9, and 10.
Standard LED indicator lamps are not compatible with the
SE-325.
For general-purpose applications, use the RK-325 Remote
Indication-and-Reset Assembly or the RK-325I Remote
Indication Assembly. Connect terminals SW, GI, +, and RI
to remote-kit terminals SW, GI, +, and CI/RI.
For 22-mm-component RK-302 applications, connect
terminal X2 of the red ground-fault indicator to GI, terminal
X2 of the red resistor-fault indicator to RI, and connect
indicator X1 terminals to +. For remote reset, connect the
normally open push-button switch across terminals + and
SW.
If indication is required from a separate voltage source, or
if separate ground-fault and resistor-fault contacts are
required, use an RK-13 Relay Interface Module. The
RK-13 mounts on the SE-325 lower terminal block and it is
compatible with the RK-302, RK-325 and RK-325I. See
Figs. 1 and 11. Contact K1 closes when the Ground-Fault
LED is on and contact K2 closes when the Resistor-Fault
LED is on.
3.7 GROUND-FAULT TESTING
Use CT-primary current injection to test the ground-fault
circuit. Fig. 12 shows test circuits using the Startco SE-400
Ground-Fault-Relay Test Unit and the SE-100T Ground-
Fault-Relay Tester. The SE-400 has a programmable output
of 0.5 to 9.9 A for a duration of 0.1 to 9.9 seconds. The
SE-100T has LO and HI outputs for 5- and 15-A resistance-
grounded systems.
A test-record form is provided in Section 7 of this
manual. Record the test results and test dates on this form to
meet the requirements of the National Electrical Code
(NEC). Retain the form so that the test data can be made
available to the authority having jurisdiction.
4. TECHNICAL SPECIFICATIONS
4.1 SE-325
Supply:
ac ........................................... 120 or 240 Vac (+10, -50%),
50/60 Hz, 10 VA
ac/dc ...................................... 120 Vdc (+40, -8%), 5 W
or 120 Vac (+10, -29%),
47 to 440 Hz, 5 VA
NOTE: Voltage between supply terminals (L1, L2) and
ground terminal (G) must not exceed 300 Vac continuous or
1,250 Vac under transient conditions.
Dimensions:
Height.................................... 150 mm (5.9")
Width.................................... 109 mm (4.3")
Depth..................................... 100 mm (4.0")
Shipping Weight....................... 1 kg (2.2 lb)
Environment:
Operating Temperature ........ -40 to 60°C
Storage Temperature ............ -55 to 80°C
Humidity ............................... 85% Non-Condensing
Ground-Fault Circuit:
CT Ratio................................ 200:5
CT Input Burden................... 0.02 Ω
Trip Level
(1) ......................... 0.5, 2.0, or 4.0 A
Frequency Response...........25 to 400 Hz,
25 to 110 Hz with
Option H
Trip Time .............................. 0.1 to 2.0 s,
0.1 to 5.0 s with
Option T
Thermal Withstand
(1) ........... 200 A Continuous,
2,500 A for 2 s
Trip-Level Accuracy ............ +10, -20%
CT Lead Resistance Limit (2)
0.5 A Trip Level............ 2 Ω
2 A Trip Level............... 5 Ω
4 A Trip Level............... 5 Ω
Trip-Time Accuracy............. 10%
Operating Mode.................... Latching,
Non-latching with
Option N
(1) Currents referred to primary of CT200 for prospective
ground-fault currents less than 4,000 A.
(2) Typical maximum CT lead resistance to meet specified
trip level accuracy.

Startco Engineering Ltd. Page 13
SE-325 Neutral-Grounding-Resistor Monitor Rev. 1
Pub. SE-325-M, May 6, 2008.
Resistor-Fault Circuit:
Neutral-To-Ground
Trip Voltage (VN) .................20 to 2,000 Vac Adjustable
NGR Trip Resistance, VN = 0
ER-600VC or ER-5KV..... 2 kΩ
ER-15KV or ER-25KV .... 6 kΩ,
50 kΩwith Option S
Neutral-To-Ground
DC-Voltage Rejection:
ER-600VC or ER-5KV .. 1.2 V
ER-15KV or ER-25KV .. 0.7 V, 4 V with Option S
Trip-Resistance Accuracy .... +5, -2% of Sensing
Resistor Resistance
Trip Time ..............................5 ± 0.5 s,
20 ± 3 s with Option S
Operating Mode .................... Latching,
Non-latching with
Option N
Output Relay:
CSA/ULContact Rating........ 1 mA to 4 A Resistive,
240 Vac or 28 Vdc
Supplemental Contact Ratings:
Make/carry 0.2 s.............. 10 A
Carry continuous............. 4 A
Break:
dc................................ 20 W resistive,
10 W inductive
(L/R = 0.04 s)
ac................................ 960 VA resistive,
700 VA inductive
(PF = 0.4)
Subject to maximums of 4 A and 240 V (ac or dc)
Contact Configuration .......... N.O. (Form A)
Fuse Rating (F1) ................... 4.0 A, 250 Vac,
Time Delay
Fuse Part Number ................. Bussman MSL-4 or
Littelfuse 313.004
Operating Mode ...................UV (Fail-Safe) or
SH (Non-Fail-Safe)
Remote Indication:
+............................................. 12 Vdc
GI/RI ..................................... Current Sink,
560 ΩInternal
Optional RK-13 Module:
Contact Ratings ..................100 mA, 120 Vac
Contact Configuration........N.O. (Form A)
Reset Input .........................24 to 120 V (ac or dc),
Isolated
PWB Conformal Coating......... MIL-1-46058 qualified,
UL QMJU2 recognized
4.2 SENSING RESISTORS
ER-600VC:
Maximum Voltage .......... 600 Vac
Maximum Current........... 30 mA
Resistance ....................... 20 kΩ
Thermal:
420 Vac ...........................Continuous
600 Vac ...........................6 minutes on,
60 minutes off
Shipping Weight ................300 g (0.7 lb)
ER-5KV:
Maximum Voltage .......... 2,500 Vac
Maximum Current........... 125 mA
Resistance ....................... 20 kΩ
Thermal ..............................Continuous
Shipping Weight ................5.0 kg (11 lbs)
ER-15KV:
Maximum Voltage .......... 8,400 Vac
Maximum Current........... 84 mA
Resistance ....................... 100 kΩ
Thermal ..............................1 minute on,
120 minutes off
Shipping Weight ................5.0 kg (11 lbs)
ER-25KV:
Maximum Voltage .......... 14,400 Vac
Maximum Current........... 144 mA
Resistance ....................... 100 kΩ
Thermal ..............................1 minute on,
120 minutes off
Shipping Weight ................20 kg (44 lbs)
4.3 CURRENT TRANSORMER
CT200:
Current Ratio................... 200:5 A
Insulation ........................ 600-V Class
Window Diameter........... 56 mm (2.2”)
Shipping Weight ............. 1 kg (2.2 lbs)
Certification ........................ CSA, Canada and USA
LR 53428
USC
R
Australia
Commonwealth of Pennsylvania
SE-325........ BOTE 1767-99
SE-325P...... BOTE 1797-00

Startco Engineering Ltd. Page 14
SE-325 Neutral-Grounding-Resistor Monitor Rev. 0
Pub. SE-325-M, May 6, 2008.
5. ORDERING INFORMATION
SE-325
120-Vac Supply
E 240-Vac Supply
D 120-Vac/dc Supply
(2)
S Extended Resistor Trip Time
H Harmonic Filtering
N Non-latching Operation
T Extended G-F Trip Time
Option List
(1)
(1)
2
List options required in order shown above.
Standard, leave blank.
SE-325P ....Approved by
The Commonwealth of Pennsylvania
for 4,800- NGR.
Requires 20-k sensing resistor.
W
W
()
Sensing Resistors:
ER-600VC.............................For system voltages up to
1 kVac
ER-5KV ................................For system voltages up to
5 kVac
ER-15KV ..............................For system voltages up to
15 kVac
ER-25KV ..............................For system voltages up to
25 kVac
Ground-Fault CT:
CT200....................................56 mm (2.2") Window
Remote Indication and Reset:
RK-302..................................Includes two LED pilot
lights, a reset push button,
and legend plates
RK-325..................................Indication-and-Reset
Assembly
RK-325I ................................Indication Assembly
RK-13....................................Relay Interface Module
6. WARRANTY
The SE-325 Neutral-Grounding-Resistor Monitor is
warranted to be free from defects in material and
workmanship for a period of five years from the date of
purchase.
Startco Engineering Ltd. will (at Startco’s option)
repair, replace, or refund the original purchase price of an
SE-325 that is determined by Startco to be defective if it
is returned to the Startco factory, freight prepaid, within
the warranty period. This warranty does not apply to
repairs required as a result of misuse, negligence, an
accident, improper installation, tampering, or insufficient
care. Startco Engineering Ltd. does not warrant products
repaired or modified by non-Startco Engineering Ltd.
personnel.
Startco Engineering Ltd. is not liable for contingent or
consequential damages; for expenses sustained as a result
of incorrect application, incorrect adjustment, or a
malfunction; or for expenses resulting from the use of, or
inability to use, the product.

Startco Engineering Ltd. Page 15
SE-325 Neutral-Grounding-Resistor Monitor Rev. 0
Pub. SE-325-M, May 6, 2008.
7. TEST PROCEDURES
7.1 GROUND-FAULT PERFORMANCE TEST
To meet the requirements of the National Electrical
Code (NEC), as applicable, the overall ground-fault
protection system requires a performance test when first
installed. A written record of the performance test is to
be retained by those in charge of the electrical installation
in order to make it available to the authority having
jurisdiction. A test-record form is provided for recording
the date and the final results of the performance tests.
The following ground-fault system tests are to be
conducted by qualified personnel:
a) Evaluate the interconnected system in accordance with
the overall equipment manufacturer’s detailed
instructions.
b) Verify proper location of the ground-fault current
transformer. Ensure the cables pass through the
ground-fault-current-transformer window. This check
can be done visually with knowledge of the circuit.
The connection of the current-transformer secondary
to the SE-325 is not polarity sensitive.
c) Verify that the system is correctly grounded and that
alternate ground paths do not exist that bypass the
current transformer. High-voltage testers and
resistance bridges can be used to determine the
existence of alternate ground paths.
d) Verify proper reaction of the circuit-interrupting
device in response to a simulated or controlled
ground-fault current. To simulate ground-fault
current, use CT-primary current injection. Fig. 12a
shows a test circuit using a Startco SE-400 Ground-
Fault-Relay Test Unit. The SE-400 has a
programmable output of 0.5 to 9.9 A for a duration of
0.1 to 9.9 seconds. Set the test current to 0.6, 2.3, or
4.6 A for SE-325 units set at 0.5, 2.0, or 4.0 A
respectively. Fig. 12b shows a test circuit using a
Startco SE-100T Ground-Fault-Relay Tester. The
SE-100T provides a test current of 0.65 or 2.75 A for
testing 0.5- and 2.0-A trip levels. Inject the test
current through the current-transformer window for at
least 2.5 seconds. Verify that the circuit under test has
reacted properly. Correct any problems and re-test
until the proper reaction is verified.
e) Record the date and the results of the test on the
attached test-record form.
SE-400
SE-325
RMT1
REMOTE
TEST 9
8
1
5
3
11 12
RMT2
L
L
N
N
L1
L1
CT1
CT2
OP1 OP2
L2
L2
a) USING SE-400
0.65 A
2.75 A
NEUTRAL
GROUNDING
RESISTOR
CT200
GROUND-FAULT CT
ER
N
R
G
R
b) USING SE-100T
SE-100T
SE-325
REMOTE
TEST
RMT
L
L
N
N
L1
L1
CT1
CT2
C
L2
L2
NEUTRAL
GROUNDING
RESISTOR
CT200
GROUND-FAULT CT
ER
N
R
G
R
LO
HI
FIGURE 12. Ground-Fault-Test Circuits
TABLE 2. GROUND-FAULT-TEST RECORD
DATE TEST RESULTS
Retain this record for the authority having jurisdiction.

Startco Engineering Ltd. Page 16
SE-325 Neutral-Grounding-Resistor Monitor Rev. 1
Pub. SE-325-M, May 6, 2008.
7.2 RESISTOR-FAULT TESTS
Perform tests with system de-energized and supply
voltage applied to the SE-325.
7.2.1 OPEN TEST
Test Equipment: 20-kΩand 100-kΩ, ¼-watt, 1% resistors
(included with SE-325).
Procedure:
•Remove connections to SE-325 R and G terminals.
•Connect the 20-kΩresistor to R and G terminals.
•Set the RES switch to 20K.
•Press RESET.
•The RESISTOR-FAULT LED should be off.
•Remove the test resistor and wait 5 seconds
(20 seconds with Option S).
PASS: The SE-325 should trip on RESISTOR FAULT.
•Connect the 100-kΩresistor to R and G terminals.
•Set the RES switch to 100K.
•Press RESET.
•The RESISTOR-FAULT LED should be off.
•Remove the test resistor and wait 5 seconds
(20 seconds with Option S).
PASS: The SE-325 should trip on RESISTOR FAULT.
To test the connected wiring, sensing resistor, and NGR:
•Reconnect SE-325 R and G connections.
•Set the RES switch to match sensing resistor.
•Press RESET.
PASS: The RESISTOR FAULT LED should be off.
7.2.2 VOLTAGE TEST
Test Equipment: 0 to 120 Vac voltage source and multimeter.
NOTE: Applying the test voltage to the R and G terminals will
damage the SE-325 and the ER sensing resistor. The RES
TRIP LEVEL is the trip voltage at terminal N, not terminal R.
Procedure:
•Check the ER sensing resistor connection to the SE-325.
•Disconnect the wire from sensing resistor terminal N.
•Set the voltage source to 0 V.
•Connect the voltage source between sensing resistor N and
G terminals.
•Set the RES TRIP LEVEL (VAC) to 20.
•Press RESET.
•The RESISTOR-FAULT LED should be off.
•Increase the test voltage to 25 Vac for 20-kΩsensors or
120 Vac for 100-kΩsensors and wait 5 seconds
(20 seconds with Option S).
PASS: The SE-325 should trip on RESISTOR FAULT.
7.3 SENSING-RESISTOR TEST
Test Equipment: Multimeter.
Procedure:
•Disconnect the sensing resistor.
•Measure the resistance between sensing-resistor terminals
R and N.
PASS: Resistance should be between 19.6 and 20.4 kΩ
for 20-kΩsensing resistors. Resistance should be between
98 and 102 kΩfor 100-kΩsensing resistors.
•Measure the resistance between sensing-resistor terminals
R and G in both directions.
PASS: Resistance should be greater than 10 MΩin both
directions.