Littelfuse Startco SE-330HV User manual

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SE-330HV MANUAL
NEUTRAL-GROUNDING-RESISTOR MONITOR
REVISION 5-M-101817
Copyright Ó2017 Littelfuse Startco.
All rights reserved.
Document Number: PM-1215-EN
Printed in Canada.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
TABLE OF CONTENTS
SECTION PAGE
1 General ................................................................. 1
1.1 Modern Resistance-Grounded Systems................. 1
1.2 SE-330HV NGR Monitoring................................. 1
2 Operation.............................................................. 3
2.1 Settings .................................................................. 3
2.1.1 GF Trip Time ............................................. 3
2.1.2 GF Trip Level............................................. 3
2.1.3 VNTrip Level ............................................. 3
2.1.4 Configuration Settings ............................... 3
2.1.4.1 Trip-Relay Mode and
Trip-Memory Mode (S2)............................ 3
2.1.4.2 Ground-Fault-Trip Latch (S3)....... 3
2.1.4.3 Resistor-Fault-Trip Latch (S4)...... 3
2.1.4.4 Sensing-Resistor Selection (S5).... 3
2.1.4.5 Frequency (S6) .............................. 4
2.1.4.6 Upgrade Mode (S8)....................... 4
2.1.5 Resistor-Fault Trip Time............................ 4
2.1.6 Resistor-Fault Trip Level ........................... 4
2.1.7 Geo-Magnetic Filter ................................... 4
2.2 Calibration ............................................................. 4
2.3 Trip Indication and Reset ...................................... 4
2.4 Remote Operation.................................................. 4
2.5 Relay K1 LED ....................................................... 5
2.6 Unit Healthy Output .............................................. 5
2.7 Diagnostic LED ..................................................... 5
2.8 Analog Output ....................................................... 5
3 Installation............................................................ 6
3.1 SE-330HV ............................................................. 6
3.2 Sensing Resistor .................................................... 6
3.3 Ground-Fault CT ................................................. 18
3.4 Isolated Ground Connection................................ 23
4 Data Interfaces................................................... 24
4.1 SD Card ............................................................... 24
4.1.1 Datalogging .............................................. 24
4.1.2 Firmware Upgrade ................................... 24
4.2 USB Interface ...................................................... 24
4.3 Network Communications................................... 24
5 Troubleshooting................................................. 25
6 Technical Specifications .................................... 27
6.1 SE-330HV ........................................................... 27
6.2 Sensing Resistors................................................. 29
6.3 Current Sensors ................................................... 30
7 Ordering Information ....................................... 31
8 Warranty ............................................................ 32
9 Test Procedures.................................................. 32
9.1 Resistor-Fault Tests ............................................. 32
9.1.1 Calibration and Open Test ....................... 32
9.1.2 Voltage Test ............................................. 32
9.2 Sensing-Resistor Test .......................................... 32
9.3 Analog-Output Test ............................................. 32
9.4 Ground-Fault Performance Test .......................... 33
Appendix A SE-330HV Revision History ................... 34
LIST OF FIGURES
FIGURE PAGE
1 Configuration Switches ............................................ 3
2 Analog-Output Connections..................................... 5
3 SE-330HV Connection Diagram.............................. 7
4 SE-330HV Outline and Panel-Mounting Details ..... 8
5 SE-330HV Outline and Surface-Mounting Details.. 9
6 SE-IP65CVR-G Weatherproof Cover Outline....... 10
7 SE-IP65CVR-G Weatherproof Cover Installation. 11
8 ER-15KV Sensing Resistor.................................... 12
9 ER-25KV Sensing Resistor.................................... 13
10 ER-35KV Sensing Resistor.................................... 14
11 ER-72KV Sensing Resistor Outline....................... 15
12 ER-72KV Sensing Resistor Mounting Details....... 16
13 ER-1000HV Sensing Resistor................................ 17
14 ER-1000HV Simplified Connection Diagram ....... 18
15 EFCT-1 Ground-Fault Current Sensor................... 19
16 SE-CS30-70 Ground-Fault Current Sensor............ 20
17 EFCT-26 and SE-CS30-26 Ground-Fault
Current Sensors ...................................................... 21
18 RK-332 Remote Indication and Reset.................... 22
19 PGA-0520 Analog Percent Current Meter ............. 22
20 Simplified Isolated-Ground Connection ................ 23
21 Ground-Fault-Test Circuit...................................... 33
LIST OF TABLES
TABLE PAGE
1 Typical Values for Tripping Systems....................... 2
2 Ground-Fault Trip Levels for Selected CT’s ........... 2
3 Ground-Fault-Test Record ..................................... 33
DISCLAIMER
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.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
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. This is an improvement
over low-resistance or solidly-grounded systems
because, in those systems, a ground-fault flash hazard
exists 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 low current 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. Consult
CEC 10-1102, NEC 250.36, and NEC 250.186 for
application details.
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 can be
conservatively estimated as ½A 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 10
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 12 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-330HV NGR MONITORING
The SE-330HV is a microprocessor-based neutral-
grounding-resistor monitor that detects NGR failures and
ground faults in resistance-grounded systems. The
SE-330HV measures NGR resistance, NGR current, and
transformer or generator neutral-to-ground voltage. The
components required to monitor an NGR are an
SE-330HV, a 100- or 200-kWER-series sensing resistor,
and a current transformer (CT).
Power-circuit elements, other than neutral-connected
NGR’s, that purposefully connect the power system to
ground are often not compatible with SE-330HV NGR
monitoring. These elements include single-phase
grounding transformers, grounded-wye-primary potential
transformers (PT’s), and grounded-wye-primary power
transformers.
The SE-330HV continuously measures NGR
resistance in an unfaulted system. It will trip on resistor
fault if NGR resistance varies from its calibrated value.
When a ground fault occurs, voltage is present on the
neutral and NGR current will flow if the NGR is healthy.
The SE-330HV will trip on ground fault if fault current
exceeds the GF TRIP LEVEL setting for an interval
equal to the GF TRIP TIME setting. However, if the
NGR fails open during a ground fault, it is possible for
fault resistance to satisfy the NGR resistance
measurement. To detect this double-fault condition, the
SE-330HV measures neutral voltage. If neutral voltage
exceeds the VNTRIP LEVEL setting, and if NGR current
is less than 5% of the current transformer (CT) rating, the
SE-330HV will trip on resistor fault. If the resistor-fault
circuit is tripped and the neutral voltage exceeds the VN
TRIP LEVEL setting for an interval greater than the GF
TRIP TIME setting, the ground-fault circuit will also
trip.
Ground-fault current is sensed by a CT with a 1- or 5-
A secondary, or by a CT (EFCT-x or SE-CS30-x) with a
50-mA secondary. The trip level of the ground-fault
circuit is adjustable from 2 to 100% of the CT rating and
trip time is adjustable from 0.1 to 10.0 seconds.
The SE-330HV has four output relays. Relay K1 is
the trip relay. Relays K2 and K3 provide ground-fault
and resistor-fault indication. K4 is a solid-state relay that
provides UNIT HEALTHY indication. Relay K1 will
operate on either a resistor fault or a ground fault, and it
can be set to operate in the fail-safe or non-fail-safe
mode for undervoltage or shunt-trip applications.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
Additional features include LED trip indication, trip
memory, front-panel and remote reset, 4-20-mA analog
output, trip event recorder, USB local communications,
microSD™ data logging, and optional network
communications.
The SE-330HV provides the following additional
features:
• When the trip level is set to MEM, the ground-fault
trip setting is defined by an internal non-volatile
memory variable. Range is 2 to 100% in 1%
increments of the CT-primary rating.
• Indication relays can be set to fail-safe or non-fail-
safe.
• The number of trip records has been increased to
100 and includes date and time stamping.
• A microSD™ card interface can be used for long-
term data logging and firmware updates. A
microSD™ card and a microSD-to-SD adapter is
included. See Section 4.1.
• For ease of connection to new devices, the RS-232
interface has been replaced by a Mini B USB port.
• Dual Ethernet ports are available with support for
fiber-optic and RJ45 interfaces.
• The IEC 61850 protocol has been added.
TABLE 1. TYPICAL VALUES FOR TRIPPING SYSTEMS
SYSTEM
VOLTAGE
(LINE-LINE)
NEUTRAL-GROUNDING
RESISTOR
SENSING
RESISTOR
GROUND-
FAULT
TRIP LEVEL
VNTRIP
LEVEL
(VOLTS)
CURRENT
(AMPERES)
RESISTANCE
(OHMS)
MODEL
RESISTANCE
(SWITCH S5
SETTING)
(AMPERES)
(VOLTS)
7,200
14,400
7,200
14,400
25,000
35,000
72,000
15
15
25
25
25
25
100
277
554
166
332
577
808
420
ER-15KV
ER-15KV
ER-15KV
ER-15KV
ER-25KV
ER-35KV
ER-72KV
100 kW
100 kW
100 kW
100 kW
100 kW
100 kW
200 kW
3.0
3.0
5.0
5.0
5.0
5.0
20.0
850
1,700
850
1,700
4,000
6,000
6,000 x 2 = 12,000
TABLE 2. GROUND-FAULT TRIP LEVELS FOR SELECTED CT’S
GF TRIP
LEVEL(1)
(%)
EFCT-X
5:0.05
(AMPERES)
SE-CS30-X
30:0.05
(AMPERES)
50:1
50:5
(AMPERES)
100:1
100:5
(AMPERES)
200:1
200:5
(AMPERES)
400:1
400:5
(AMPERES)
2
4
6
8
10
20
40
60
80
100
0.10
0.20
0.30
0.40
0.50
1.00
2.00
3.00
4.00
5.00
0.60
1.20
1.80
2.40
3.00
6.00
12.0
18.0
24.0
30.0
*
*
*
*
5
10
20
30
40
50
*
*
*
8
10
20
40
60
80
100
*
*
12
16
20
40
80
120
160
200
*
16
24
36
40
80
160
240
320
400
(1) When set to MEM, range is 2 to 100% in 1% increments.
* Setting not recommended.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
2. OPERATION
2.1 SETTINGS
2.1.1 GF TRIP TIME
GF TRIP TIME (definite time) is adjustable from 0.1 to 10.0
seconds. Time-coordinated ground-fault protection requires
this setting to be longer than the trip times of downstream
ground-fault devices.
A trip-time accumulator provides a ground-fault memory
function for detection of intermittent faults. The accumulated
time increases when a ground fault is detected and decreases
when a ground fault is not detected. A trip will eventually
occur when the time for fault current above the trip level is
greater than the time for fault current below the trip level.
2.1.2 GF TRIP LEVEL
The SE-330HV uses a Discrete-Fourier Transform
(DFT) Algorithm to measure the fundamental component
of NGR current.
Choose an NGR let-through current and a ground-fault
trip level according to the guidelines in Section 1.1.
Set the ground-fault trip level as a percentage (2 to 100) of
the CT-primary rating. When the GF Trip Level is set to
MEM, the ground-fault setting stored in non-volatile
memory is used. This parameter must be set using a PC
running the SE-MON330 software connected to the USB
interface. The setting range is 2 to 100% of CT primary
rating in 1% increments. The default value is 15%. Inputs
are provided for 5-, 1-, and 0.05-A-secondary CT’s.
Typical values for 15-, 25-, and 100-A tripping systems
are shown in Table 1. Ground-fault trip levels for selected
CT’s are shown in Table 2. Refer to
the NGR Monitor Set-Point Assistant at
www.littelfuse.com/relayscontrols for other systems. The
Set-Point Assistant is included with the SE-MON330
software.
2.1.3 VN TRIP LEVEL
The SE-330HV uses a DFT algorithm to measure the
fundamental component of neutral voltage (VN).
If neutral voltage is greater than the VNTRIP LEVEL
setting for the duration of the resistor-fault trip time and
ground-fault current is less than 5% of the CT rating, the SE-
330HV will trip on resistor fault. If the resistor-fault circuit
is tripped and the neutral voltage exceeds the VNTRIP
LEVEL setting for an interval greater than the GF TRIP
TIME setting, the ground-fault circuit will also trip.
The VNTRIP LEVEL range is 100 to 10,000 V with
switch S5 in the 100-kW(Vx1) position, and the range is
200 to 20,000 V with switch S5 in the 200-kW(Vx2)
position. Calculate the voltage across the NGR when
NGR current is equal to the pick-up current of the ground-
fault circuit. Set the VNTRIP LEVEL at the next largest
value. See Fig. 1 and Section 2.1.4.4.
Typical values for 15-, 25- and 100-A tripping systems
are shown in Table 1. Refer to the NGR Monitor Set-
Point Assistant at www.littelfuse.com/relayscontrols for
other systems.
NOTE:A resistor-fault trip is held off if the ground-fault
current is above 5% of the CT rating.
2.1.4 CONFIGURATION SETTINGS
Eight configuration switches (S1 to S8) and a
calibration button are located behind the access cover on
the front panel. See Fig. 1.
FIGURE 1. Configuration Switches.
2.1.4.1 TRIP-RELAY MODE AND TRIP-MEMORY
MODE (S2)
Set switch S2 to select the operating mode of trip relay
K1. In the non-fail-safe mode, relay K1 energizes and its
contact closes when a trip occurs. The non-fail-safe mode
can be used to trip shunt-trip circuit breakers. In the non-
fail-safe mode, SE-330HV trips are reset when supply
voltage is cycled.
In the fail-safe mode, relay K1 energizes and its contact
closes if there are no trips. Contacts open if there is a trip, a
loss of supply voltage, or a processor failure. In the fail-safe
mode, SE-330HV trips are not reset when supply voltage is
cycled.
NOTE:Switch S2 does not affect the operating modes of
relays K2, K3, and K4.
2.1.4.2 GROUND-FAULT-TRIP LATCH (S3)
Set switch S3 to select latching or non-latching ground-
fault-circuit operation. Non-latching operation defeats
ground-fault trip-memory. See Section 2.3.
2.1.4.3 RESISTOR-FAULT-TRIP LATCH (S4)
Set switch S4 to select latching or non-latching resistor-
fault-circuit operation. Non-latching operation defeats
resistor-fault trip-memory.See Section 2.3
2.1.4.4 SENSING-RESISTOR SELECTION (S5)
Set switch S5 to the resistance of the sensing resistor. For
the ER-15KV, ER-25KV, and ER-35KV, select 100 kW.
For the ER-1000HV and ER-72KV, select 200 kW. Switch
S5 sets the resistor-fault trip value and the VNTRIP LEVEL
range. See Section 2.1.3.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
2.1.4.5 FREQUENCY (S6)
Set switch S6 to 50 or 60 Hz to tune the digital filter to
the line frequency of the monitored system.
2.1.4.6 UPGRADE MODE (S8)
The microSD™ card is used for firmware upgrades.
See Section 4.1.2 for upgrade instructions.
NOTE: An upgrade causes an SE-330HV restart and this
may cycle the output relays.
2.1.5 RESISTOR-FAULT TRIP TIME
The resistor-fault trip time can be adjusted from 12
(default) to 60 seconds using the SE-MON330 software or
via network communications.
2.1.6 RESISTOR-FAULT TRIP LEVEL
The resistor-fault trip level can be adjusted using the
SE-MON330 software or via network communications.
See Section 6.1.
2.1.7 GEO-MAGNETIC FILTER
A low-frequency ground current can be caused by the
Earth’s magnetic field and from charged clouds passing
overhead during a thunderstorm. In some rare conditions,
this can cause a false resistor-fault trip. Enabling the geo-
magnetic filter and increasing the resistor-fault trip time
can help counteract these effects.
A trip time of 30 seconds is recommended when the
geo-magnetic filter is enabled.
The geo-magnetic filter is disabled by default, but can
be enabled using the SE-MON330 software or via network
communications.
2.2 CALIBRATION
The SE-330HV measures the resistance change of the
NGR relative to the NGR-resistance value determined at
the time of calibration. When the resistance change is
greater than a threshold amount (2,500 Ωfor 100-kΩ
systems, 5,000 Ωfor 200-kΩsystems), a resistor-fault trip
occurs. Calibrate the SE-330HV on new installations, if
the NGR is changed, or if the sensing resistor is changed.
NOTE:If the SE-330HV is not calibrated and is supplied
from the load side of the breaker (non-fail-safe mode),
calibrate within the resistor-fault trip time after power-up
or it may trip and interrupt its supply. See Section 2.1.5.
The CALIBRATION button is located behind the
access cover on the front panel, and it is recessed to
prevent inadvertent activation.
NOTE:Calibration must be performed with the
SE-330HV connected to the sensing resistor and NGR of
the installed system.
To calibrate, press and hold the CALIBRATION button
until the green CALIBRATED LED turns off and returns
to on (if the LED is already off, press and hold until the
LED turns on). Calibration takes approximately two
seconds. If calibration is not successful, a resistor-fault
trip occurs, the RESISTOR FAULT TRIP LED will be on,
the CALIBRATED LED will be off, and the
DIAGNOSTIC LED will flash the calibration-error code.
See Section 2.7.
The SE-330HV may be calibrated remotely using
the SE-MON330 software with the USB interface or the
communications options.
If latching resistor fault (switch S4) is selected, the
calibration-error code flashes until RESET is pressed even
if the CALIBRATED LED is on.
The calibration value is stored in non-volatile memory.
2.3 TRIP INDICATION AND RESET
Red LED's and indication relays indicate ground-fault and
resistor-fault trips. The indication relays K2 (GF) and K3
(RF) operate in fail-safe or non-fail-safe mode. The default
is non-fail-safe mode. In this mode, the relays are energized
when a fault occurs. The relay mode setting is stored in non-
volatile memory and can be set using the
SE-MON330 software or network communications.
When a trip occurs with latching operation selected, the
SE-330HV remains tripped until reset with the front panel
button or the remote-reset input. See Sections 2.1.4.3 and
2.1.4.4. Terminals 15 and 16 are provided for remote reset
as shown in Fig. 3. The reset circuit responds only to a
momentary closure so that a jammed or shorted button does
not prevent a trip. The front-panel RESET button is
inoperative when terminal 15 is connected to terminal 16. If
non-latching operation is selected, trips and corresponding
indication automatically reset when the fault clears and
power-up trip memory is defeated even when configuration
switch S2 is set to fail-safe.The maximum automatic reset
time is 2.8 s.
The red DIAGNOSTIC LED annunciates latched
calibration-error and remote trips. See Section 2.7.
When supply voltage is applied with switch S2 set to
FAIL-SAFE, the SE-330HV returns to its state prior to
loss of supply voltage. When supply voltage is applied
with switch S2 set to NON-FAIL-SAFE, SE-330HV trips
are reset.When a local, remote, or network reset is issued,
both trip LED's will flash if they are off.
Resistor-fault-trip reset can take up to one second.
Resistor-fault trip-memory can take up to three seconds after
SE-330HV power up.
2.4 REMOTE OPERATION
Relays K2 and K3 can be used for remote indication,
and terminals 15 and 16 are provided for remote reset.
RK-332 Remote Indication and Reset components are
shown in Fig. 18. Connect them as shown in Fig. 3. RK-
332 components are not polarity sensitive.
Indication relays can be set to fail-safe or non-fail-safe
operation using the SE-MON330 software or network

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
communications. The default mode is non-fail-safe. In
non-fail-safe mode, relays energize on fault.
Network-enabled SE-330HV’s can be remotely tripped
and reset by the network master. The red DIAGNOSTIC
LED indicates a network-initiated trip. See Section 2.7.
Refer to the appropriate SE-330HV communications
manual.
2.5 RELAY K1 LED
The yellow RELAY K1 LED follows the state of relay
K1 and is on when K1 is energized (contact closed).
2.6 UNIT HEALTHY OUTPUT
UNIT HEALTHY relay K4 is energized when the
processor is operating. It can be ordered with N.O. or
N.C. contacts. See Section 7.
NOTE:The output changes state momentarily during a
processor reset.
NOTE:K4-contact rating is 100 mA maximum.
2.7 DIAGNOSTIC LED
The DIAGNOSTIC LED is used to annunciate trips
without individual LED indication. The number of short
LED pulses between pauses indicates the cause of the trip.
By default, both critical and non-critical diagnostic flash
codes are shown. Non-critical diagnostic codes include SD
Card status and USB Error status. All other diagnostic
codes are considered critical.
Starting with SE-330HV firmware version 2.60 and SE-
MON330 software version 3.8, the SE-330HV can be
configured to show only critical diagnostic codes. In this
configuration, non-critical diagnostic codes will not be
indicated with the DIAGNOSTIC LED.
Diagnostic messages are always visible with the SE-
MON330.
See Sections 4.2 and 5.
2.8 ANALOG OUTPUT
An isolated 4-20-mA output indicates NGR current with
full-scale output corresponding to the CT rating. An
internal 24-Vdc supply allows the analog output to be
connected as a self-powered output. Power from an
external supply is required for loop-powered operation.
See Fig. 2. A PGA-0520 analog meter can be panel-
mounted to display the NGR current. See Fig. 19 and
Section 7.
FIGURE 2. Analog-Output Connections.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
3. INSTALLATION
3.1 SE-330HV
Outline and panel-cutout dimensions for the SE-330HV
are shown in Fig. 4. To panel mount the SE-330HV,
insert it through the panel cutout and secure it with the
four included 8-32 locknuts and flat washers.
If an optional SE-IP65CVR-G Hinged Cover is used,
follow the included installation instructions. See Figs. 6
and 7.
All connections to the SE-330HV are made with plug-
in, wire-clamping terminal blocks. Each plug-in terminal
block can be secured to the SE-330HV by two captive
screws for reliable connections.
Outline dimensions and mounting details for surface
mounting the SE-330HV are shown in Fig. 5. Fasten the
optional surface-mount adapter to the mounting surface
and make connections to the adapter terminal blocks.
Follow Fig. 5 instructions to mount or remove the
SE-330HV.
Ground terminal 7 (G) and connect terminal 6 (R) to
the sensing-resistor R terminal.
Use terminal 1 (L1) as the line terminal on ac systems,
or the positive terminal on dc systems. Use terminal 2
(L2/N) as the neutral terminal on ac systems or the
negative terminal on dc systems. Connect terminal
3 ( ) to ground.
NOTE: Disconnect terminal 1 (L1) and terminal 2 (L2/N)
before performing dielectric strength testing of the control
panel.
NOTE: Connections to terminals 4 (SPG) and 5 (SPGA)
are not required when using the SE-330HV hardware
revision 10 and higher. However, it is recommended to
connect terminal 4 to terminal 5 to maintain backwards
compatibility with the older SE-330HV series (hardware
revision 01A and lower).
3.2 SENSING RESISTOR
Outline and mounting details for the ER-15KV,
ER-25KV, ER-35KV and ER-72KV sensing resistors are
shown in Figs. 8, 9, 10, 11, and 12. Install the NGR and the
sensing resistor near the transformer or generator. When
installed 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. 3. Separately connect sensing-resistor
terminal N and the NGR to the neutral to include neutral
connections in the monitored loop. Alternately, if the NGR
connection to system neutral need not be monitored,
connect terminal N to the NGR neutral terminal. 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. See Note 3 in Fig. 3.
Outline and mounting details for the ER-1000HV
Sensing Resistor are shown in Fig. 13. This sensing resistor
can be used to monitor a low-voltage very-high-resistance
NGR. See the simplified diagram in Fig. 14.
NOTE: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: A parallel ground path created by moisture can
result in a false resistor-fault trip. Moisture sources
include wind-driven rain or snow, and condensation.
Sensing-resistor terminal R and its connection to SE-
330HV terminal R, including interposing terminal blocks,
must remain dry.
NOTE:The neutral-to-sensing-resistor-terminal-N 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
(8.36 mm2) or larger. Since current through this
conductor is always less than 250 mA, a 14 AWG
(2.08 mm2) conductor insulated to the system voltage is
more than sufficient.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 3. SE-330HV Connection Diagram.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 4. SE-330HV Outline and Panel-Mounting Details.

Page 9
SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 5. SE-330HV Outline and Surface-Mounting Details.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 6. SE-IP65CVR-G Weatherproof Cover Outline.

Page 11
SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 7. SE-IP65CVR-G Weatherproof Cover Installation.

Page 12
SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 8. ER-15KV Sensing Resistor.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 9. ER-25KV Sensing Resistor.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 10. ER-35KV Sensing Resistor.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 11. ER-72KV Sensing Resistor Outline.

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SE-330HV Neutral-Grounding-Resistor Monitor Rev. 5-M-101817
FIGURE 12. ER-72KV Sensing Resistor Mounting Details.