Protection Relays
Neutral-Grounding-Resistor Monitoring
SE-330, SE-330HV SERIES
Neutral-Grounding-Resistor Monitor
Description
The SE-330 is an advanced ground-fault and neutral-grounding-
resistor monitoring relay that is compliant with Rule10-302 of the
2018 Canadian Electrical Code Part I (CE Code). It measures neutral
current, neutral-to-ground voltage, and neutral-to-ground resistance.
It provides continuous monitoring of the neutral-to-ground path to
verify that the neutral-grounding resistor (NGR) is intact and that it
has not been bypassed or shorted. An open NGR renders current-
sensing ground-fault protection inoperative and could result in a false
belief that the system is functioning properly. A shorted NGR results
in higher-than-expected ground-fault current.The SE-330 can be used
with low- and medium-voltage transformers and generators with
low- or high-resistance grounding used in processing, manufacturing,
chemical, pulp and paper, petroleum, and water-treatment facilities.
For high-voltage applications, use the SE-330HV. For applications that
require conformance to Australian standards, use the SE-330AU.
Simplified Circuit Diagram
Resistor Monitoring
The SE-330 combines the measured values of resistance, current,
and voltage to continuously determine that an NGR is intact. It is
able to detect an open or shorted resistor with or without a ground
fault present. Sensing resistors are matched to the system voltage
and are used to monitor NGRs on systems up to 72 kV.
ꢄꢅ
B
ER SERIES
Ground-Fault Monitoring
SE-330 SERIES
ꢀꢁensinꢂ Resistorꢃ
The SE-330 uses an application-appropriate current transformer to
reliably detect ground-fault currents as small as 100 mA. Discrete-
FourierTransform (DFT) filtering ensures that false trips due to
harmonic noise from adjustable-speed drives do not occur. Should
the resistor open and a ground fault subsequently occur, the SE-330
will detect the fault through voltage measurement, while other
current-only sensing relays would be ineffective.
ꢀꢄꢅR ꢆonitorꢃ
ꢀꢁR
ꢂꢆ
ꢂꢃ
A
For detailed wiring diagram, see adjacent page.
Ordering Information
POWER
SUPPLY
K4 UNIT HEALTHY
ORDERING
NUMBER
COMM
CONTACT
Pulsing Ground-Fault Location
X
The SE-330 is capable of controlling a pulsing contactor, which is
used to switch the NGR resistance in a pulsing-compatible NGR
package.The resulting ground-fault current is distinguishable from
charging currents and noise and will only appear upstream of the
ground fault, making fault location fast and easy, even without
isolating feeders or interrupting loads.
SE-330
-
X
X
-
0
0=USB Only
1=DeviceNet
3=EtherNet
(Dual RJ45)
SE-330
for applications
35 kV or less
4=EtherNet
(SC Fiber & RJ45)
0=120/240
Vac/Vdc
0=Normally Open
1=Normally Closed
5=EtherNet
(Dual SC Fiber)
6=IEC61850
(Dual RJ45)
Accessories
SE-330HV
for 72 kV
applications
2=48 Vdc
ER Series Sensing Resistor
A
Required interface between the power system and the
SE-330/SE-330HV. Eliminates hazardous voltage levels at
the relay.
7=IEC61850
(SC Fiber & RJ45)
8=IEC61850
(Dual SC Fiber)
B
ELCT5 Series Ground-Fault CurrentTransformer
Sensitive ground-fault current detection (5 A primary).
NOTE: For Australian applications, see the SE-330AU.
ACCESSORIES
ER Series Sensing Resistor
Current Transformer
SE-IP65CVR-G
SE-MRE-600
RK-332
NGRM-ENC
PGA-0520
SE-330-SMA
REQUIREMENT
Required
Required
Optional
Optional
Optional
Optional
Optional
Optional
ELCT30 Series Ground-Fault CurrentTransformer
Sensitive ground-fault current detection (30 A primary).
Other CurrentTransformer
For low-resistance NGRs choose a CT primary
approximately equal to the NGR rating. Inputs are
provided for 1- and 5- A- secondary CTs.
SE-IP65CVR-G HingedTransparent Cover
Watertight cover, tamper resistant, IP65 protection.
Littelfuse reserves the right to make product changes, without notice. Material in this document is as accurate as known at the time of publication. Visit Littelfuse.com for the most up-to-date information.
Rev: 4-D-042519
Based on SE-330 Manual Rev: 11-A-063018
Based on SE-330 HV Manual Rev: 5-M-101817
© 2019 Littelfuse Protection Relays & Controls
© 2018 Littelfuse Protection Relays & Controls
Littelfuse.com/se-330 Littelfuse.com/se-330hv
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