Littelfuse SE-330 User manual

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SE-330 MANUAL
NEUTRAL-GROUNDING-RESISTOR MONITOR
REVISION 10-P-101817
Copyright Ó2017 Littelfuse Startco
All rights reserved.
Document Number: PM-1200-EN
Printed in Canada.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
TABLE OF CONTENTS
SECTION PAGE
1 General ................................................................. 1
1.1 Modern Resistance-Grounded Systems................. 1
1.2 SE-330 NGR Monitoring ...................................... 1
2 Operation.............................................................. 2
2.1 Settings .................................................................. 2
2.1.1 GF Trip Time ............................................. 2
2.1.2 GF Trip Level............................................. 2
2.1.3 VNTrip Level ............................................. 2
2.1.4 Pulse-Period Adjustment............................ 3
2.1.5 Configuration Settings ............................... 3
2.1.5.1 Relay K1 Function (S1) ................ 4
2.1.5.2 Trip-Relay Mode and
Trip-Memory Mode (S2)............................ 4
2.1.5.3 Ground-Fault-Trip Latch (S3)....... 4
2.1.5.4 Resistor-Fault-Trip Latch (S4)...... 4
2.1.5.5 Sensing-Resistor Selection (S5).... 4
2.1.5.6 Frequency (S6) .............................. 4
2.1.5.7 Upgrade Mode (S8)....................... 4
2.1.6 Resistor-Fault Trip Time............................ 4
2.1.7 Resistor-Fault Trip Level ........................... 4
2.1.8 Geo-Magnetic Filter ................................... 4
2.2 Calibration ............................................................. 4
2.3 Pulsing Operation .................................................. 5
2.4 Trip Indication and Reset ...................................... 5
2.5 Remote Operation.................................................. 5
2.6 Relay K1 LED ....................................................... 5
2.7 Unit Healthy Output .............................................. 5
2.8 Diagnostic LED ..................................................... 5
2.9 Analog Output ....................................................... 6
3 Installation............................................................ 6
3.1 SE-330 ................................................................... 6
3.2 Sensing Resistor .................................................. 12
3.3 Ground-Fault CT ................................................. 20
3.4 Isolated Ground Connection................................ 25
3.5 Pulsing Connection.............................................. 25
4 Data Interfaces................................................... 26
4.1 SD Card ............................................................... 26
4.1.1 Datalogging .............................................. 26
4.1.2 Firmware Upgrade ................................... 26
4.2 USB Interface ...................................................... 26
4.3 Network Communications................................... 26
5 Troubleshooting................................................. 27
6 Technical Specifications.................................... 29
6.1 SE-330 ................................................................. 29
6.2 Sensing Resistors................................................. 31
6.3 Current Sensors ................................................... 32
7 Ordering Information ....................................... 33
8 Warranty ............................................................ 34
9 Test Procedures.................................................. 34
9.1 Resistor-Fault Tests ............................................. 34
9.1.1 Calibration and Open Test ....................... 34
9.1.2 Voltage Test ............................................. 34
9.2 Sensing-Resistor Test .......................................... 34
9.3 Analog-Output Test ............................................. 34
9.4 Ground-Fault Performance Test .......................... 35
Appendix A SE-330 Revision History ............................. 36
LIST OF FIGURES
FIGURE PAGE
1 Configuration Switches ............................................ 3
2 Analog-Output Connections..................................... 6
3 SE-330 Connection Diagram ................................... 7
4 SE-330 Outline and Panel-Mounting Details........... 8
5 SE-330 Outline and Surface-Mounting Details ....... 9
6 SE-IP65CVR-G Weatherproof Cover Outline....... 10
7 SE-IP65CVR-G Weatherproof Cover Installation. 11
8 ER-600VC Sensing Resistor .................................. 12
9 SE-MRE-600 Moisture-Resistant Enclosure Outline13
10 ER-600VC Installed in SE-MRE-600...................... 14
11 ER-5KV Sensing Resistor...................................... 15
12 ER-5WP Sensing Resistor...................................... 16
13 ER-15KV Sensing Resistor.................................... 17
14 ER-25KV Sensing Resistor.................................... 18
15 ER-35KV Sensing Resistor.................................... 19
16 EFCT-1 Ground-Fault Current
Sensor ..................................................................... 21
17 SE-CS30-70 Ground-Fault
Current Sensor........................................................ 22
18 EFCT-26 and SE-CS30-26 Ground-
Fault Current Sensors ............................................. 23
19 RK-332 Remote Indication and Reset.................... 24
20 PGA-0520 Analog Percent Current Meter ............. 24
21 Simplified Isolated-Ground Connection ................ 25
22 Simplified Pulsing Connection............................... 25
23 Ground-Fault-Test Circuits .................................... 35
LIST OF TABLES
TABLE PAGE
1 Typical Values for Tripping Systems....................... 3
2 Ground-Fault Trip Levels for Selected CT’s ........... 3
3 Ground-Fault-Test Record ..................................... 35
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-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-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-330 NGR MONITORING
The SE-330 is a microprocessor-based neutral-
grounding-resistor monitor that detects NGR failures and
ground faults in resistance-grounded systems. The
SE-330 measures NGR resistance, NGR current, and
transformer or generator neutral-to-ground voltage. The
components required to monitor an NGR are an SE-330, a
20- or 100-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-330 NGR
monitoring. These elements include single-phase
grounding transformers, grounded-wye-primary potential
transformers (PT’s), and grounded-wye-primary power
transformers.
The SE-330 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-330 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-330 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-330 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.
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-330 has four output relays. Relay K1 can be
assigned a trip or a pulsing function. Relays K2 and K3
provide ground-fault and resistor-fault indication. K4 is a
solid-state relay that provides UNIT HEALTHY
indication. When relay K1 is assigned the trip function, it
will operate on either a resistor fault or ground fault, and
it can be set to operate in the fail-safe or non-fail-safe
mode for undervoltage or shunt-trip applications. When

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
the pulsing function is selected, relay K1 is used to
control a contactor to assist in locating faults.
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-330 provides additional features over the
SE-330 legacy model (revision 04 or less):
• 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.
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-330 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
5-, 15-, and 25-A tripping systems are shown in Table 1.
Ground-fault trip levels for selected CT’s are shown in
Table 2. For other systems, refer to the NGR Monitor Set-
Point Assistant at www.littelfuse.com/relayscontrols.The
Set-Point Assistant is included with the SE-MON330
software.
2.1.3 VN TRIP LEVEL
The SE-330 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-330 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 20 to 2,000 V with switch
S5 in the 20-kW(Vx1) position, and the range is 100 to
10,000 V with switch S5 in the 100-kW(Vx5) 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 2.1.5.5.
Typical values for 5-, 15-, and 25-A tripping systems are
shown in Table 1. For an NGR resistance greater than 2
kW, use a 100-kWsensing resistor. For other systems, refer
to the NGR Monitor Set-Point Assistant at
www.littelfuse.com/relayscontrols.
NOTE:A resistor-fault trip is held off if the ground-fault
current is above 5% of the CT rating.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
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)
480
600
2,400
4,160
480
600
2,400
4,160
7,200
14,400
4,160
7,200
14,400
25,000
35,000
5
5
5
5
15
15
15
15
15
15
25
25
25
25
25
55
69
277
480
18
23
92
160
277
554
96
166
332
577
808
ER-600VC
ER-600VC
ER-5KV
ER-5KV
ER-600VC
ER-600VC
ER-5KV
ER-5KV
ER-15KV
ER-15KV
ER-5KV
ER-15KV
ER-15KV
ER-25KV
ER-35KV
20 kW
20 kW
20 kW
20 kW
20 kW
20 kW
20 kW
20 kW
100 kW
100 kW
20 kW
100 kW
100 kW
100 kW
100 kW
1.0
1.0
1.0
1.0
3.0
3.0
3.0
3.0
3.0
3.0
5.0
5.0
5.0
5.0
5.0
60
100
340
800
60
100
340
800
170x5=850
340x5=1,700
800
170x5=850
340x5=1,700
800x5=4,000
1,200x5=6,000
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.
2.1.4 PULSE-PERIOD ADJUSTMENT
Pulse period is the cycle time of relay K1 when the
SE-330 is configured for pulsing operation. Pulse period
is adjustable from 1.0 to 3.0 seconds with a fixed duty
cycle of 50%. For example, with the 1.0-s setting, relay
K1 will alternately be energized for 0.5 seconds and de-
energized for 0.5 seconds when pulsing is enabled.
See Section 2.3 for detailed pulsing operation
information.
NOTE:For pulsing configuration, set switch S1 to K1 =
PULSING and install an external pulse-enable switch.
2.1.5 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.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
2.1.5.1 RELAY K1 FUNCTION (S1)
Set switch S1 to K1 = TRIP to assign the trip function
to relay K1 and to activate switch S2. Relay K1 will
change state when a resistor-fault or ground-fault trip
occurs.
Set switch S1 to K1 = PULSING to configure relay K1
for pulsing operation. See Section 2.3.
2.1.5.2 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-330 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-330 trips are not reset when supply
voltage is cycled.
NOTE:Switch S2 does not affect the operating modes of
relays K2, K3, and K4.
NOTE:Switch S2 only affects relay K1 operating mode
when K1 is assigned the trip function (switch S1 set to K1
= TRIP). Trip memory is enabled when K1 is set to the
fail-safe mode, regardless of the switch S1 setting.
2.1.5.3 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 Sections 2.1.5.2 and 2.4.
2.1.5.4 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 Sections 2.1.5.2
and 2.4
2.1.5.5 SENSING-RESISTOR SELECTION (S5)
Set switch S5 to the resistance of the sensing resistor. For
the ER-600VC, ER-5KV, and ER-5WP, select 20 kW. For
the ER-15KV, ER-25KV, and ER-35KV, select 100 kW.
Switch S5 sets the resistor-fault trip value and the VNTRIP
LEVEL range. See Section 2.1.3.
2.1.5.6 FREQUENCY (S6)
Set switch S6 to 50 or 60 Hz to tune the digital filter to
the line frequency of the monitored system.
2.1.5.7 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-330 restart and this may
cycle the output relays.
2.1.6 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.
2.1.7 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.
2.1.8 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-330 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 (500 Ωfor 20-kΩ
systems, 2,500 Ωfor 100-kΩsystems), a resistor-fault trip
occurs. Calibrate the SE-330 on new installations, if the
NGR is changed, or if the sensing resistor is changed.
NOTE:If the SE-330 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 2.1.6.
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-330
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 2.8.
The SE-330 may be calibrated remotely using
the SE-MON330 software with the USB interface or the
communications options.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
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 PULSING OPERATION
If switch S1 is set to K1 = PULSING, pulsing occurs
when terminal 16 is connected to terminal 17. Relay K1
operates at a 50% duty cycle and cycle time is adjustable
from 1.0 to 3.0 seconds. When terminals 16 and 17 are
not connected, K1 is not energized and its contact is open.
Relay K1 can be used to control a contactor rated for
use at the line-to-neutral voltage. The contactor causes
changes in neutral-to-ground resistance by adding or
shorting portions of the NGR. See Section 3.5. Pulsing
ground-fault current appears as zero-sequence current
upstream from the fault.
Pulsing ground-fault current is distinguishable from
charging current and noise, and it can be traced with a
clip-on ammeter or current probe. If pulsing current is
detected on a cable or conduit, the fault is downstream.
Systematic testing allows faults to be located without
isolating feeders or interrupting loads.
Stop pulsing when a fault is located.
2.4 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-330 remains tripped until reset with the front panel
button or the remote-reset input. See Sections 2.1.5.3 and
2.1.5.4. 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 2.8.
When supply voltage is applied with switch S2 set to
FAIL-SAFE, the SE-330 returns to its state prior to loss
of supply voltage unless switch S3 or S4 is set to non-
latching. When supply voltage is applied with switch S2
set to NON-FAIL-SAFE, SE-330 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 trip can take up to three
seconds after SE-330 power up.
2.5 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. 19. 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
communications. The default mode is non-fail-safe. In
non-fail-safe mode, relays energize on fault.
Network-enabled SE-330’s can be remotely tripped and
reset by the network master. The red DIAGNOSTIC
LED indicates a network-initiated trip. See Section 2.8.
Refer to the appropriate SE-330 communications manual.
2.6 RELAY K1 LED
The yellow RELAY K1 LED follows the state of relay
K1 and is on when K1 is energized (contact closed).
2.7 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 K4 output changes state momentarily during
a processor reset.
NOTE:K4-contact rating is 100 mA maximum.
2.8 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-330 firmware version 2.60 and SE-
MON330 software version 3.8, the SE-330 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.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
2.9 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. 20 and
Section 7.
FIGURE 2. Analog-Output Connections.
3. INSTALLATION
3.1 SE-330
Outline and panel-cutout dimensions for the SE-330 are
shown in Fig. 4. To panel mount the SE-330, 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-330 are made with plug-in,
wire-clamping terminal blocks. Each plug-in terminal
block can be secured to the SE-330 by two captive screws
for reliable connections.
Outline dimensions and mounting details for surface
mounting the SE-330 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-330.
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-330 hardware revision
10 and higher. However, it is recommended to connect
terminal 4 to terminal 5 to maintain backwards
compatibility with the older SE-330 series (hardware
revision 04A and lower).

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 3. SE-330 Connection Diagram.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 4. SE-330 Outline and Panel-Mounting Details.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 5. SE-330 Outline and Surface-Mounting Details.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 6. SE-IP65CVR-G Weatherproof Cover Outline.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 7. SE-IP65CVR-G Weatherproof Cover Installation.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
3.2 SENSING RESISTOR
Outline and mounting details for the ER-600VC,
ER-5KV, ER-5WP, ER-15KV, ER-25KV, and ER-35KV
sensing resistors are shown in Figs. 8, 11, 12, 13, 14, and
15. 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.
An optional SE-MRE-600 Moisture-Resistant Enclosure
is available for applications which may expose an
ER-600VC to moisture. See Figs. 9 and 10. The
weather-protected ER-5WP shown in Fig. 12 is an
ER-5KV with moisture-resistant terminal covers. Use an
ER-5WP in applications in which it might be exposed to
moisture. The ER-15KV, ER-25KV, and ER-35KV
include moisture-resistant terminal covers. Use suitable
water-tight fittings. 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.
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-330
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.
FIGURE 8. ER-600VC Sensing Resistor.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 9. SE-MRE-600 Moisture-Resistant Enclosure Outline.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 10. ER-600VC Installed in SE-MRE-600.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 11. ER-5KV Sensing Resistor.

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SE-330 Neutral-Grounding-Resistor Monitor Rev. 10-P-101817
FIGURE 12. ER-5WP Sensing Resistor.