Protection Relays & Controls
Neutral-Earthing-Resistor Monitoring
SE-330AU SERIES
Neutral-Earthing-Resistor Monitor - New Revision
Description
The SE-330AU is an advanced earth-fault and earthing-resistor
monitoring relay for low- and medium-voltage transformers and
generators. It monitors neutral current, neutral-to-earth voltage,
and neutral-to-earth resistance. It provides continuous
monitoring of the neutral-to-earth path to verify that the neutral-
earthing resistor (NER) is intact. This is of utmost importance—
an open NER renders current-sensing earth-fault protection
inoperative and could result in a false belief that the system is
functioning properly. The SE-330AU earth-fault function complies
with AS/NZS 2081.3:2002. Outputs include four relay outputs,
and an analog output. A mini USB port is included to view
measured values, configure settings, and check event records.
An on-board micro SD card can be used for long-term data
logging. Network communications options are available. For
non-AS/NZS 2081 applications, see the SE-330 or SE-330HV.
Resistor Monitoring
Simplified Circuit Diagram
The SE-330AU combines the measured values of resistance,
current, and voltage to continuously determine that the NER is
intact. It is able to detect a resistor failure with or without an
earth fault present. Sensing resistors are matched to the system
voltage and are used to monitor NGRs on systems up to 35 kV.
CT
B
ER SERIES
(Sensing Resistor)
Earth-Fault Monitoring
SE-330AU
SERIES
L1
L2
(NER Monitor)
NER
A
The SE-330AU uses a 5- or 30-A-primary current transformer to
provide a pickup-setting range of 0.125 to 5 A or 0.75 to 30 A to
comply with AS/NZS 2081.3:2002. DFT filtering ensures that
false trips due to harmonic noise from adjustable-speed drives
do not occur. Open-CT detection is provided.
Accessories
A
K4 UNIT HEALTHY
CONTACT
Ordering Information
ORDERING
NUMBER
POWER
SUPPLY
COMM
ER Series Sensing Resistor
Required interface between the power system
and the SE-330AU. Eliminates hazardous voltage
levels at the relay.
EFCT Series Earth-Fault Current Transformer
Sensitive earth-fault current detection (5 A primary).
SE-CS30 Series Earth-Fault Current Transformer
SE-330AU -
X
X
-
0
X
SE-330AU
for all apps.
35 kV or less
SE-330HV
for 72 kV
apps.
0=USB Only
1=DeviceNet
3=EtherNet
(Dual RJ45)
4=EtherNet
0=120/240 (SC Fiber & RJ45)
Vac/Vdc 5=EtherNet
(Dual SC Fiber)
2=48 Vdc 6=IEC61850
(Dual RJ45)
7=IEC61850
(SC Fiber & RJ45)
8=IEC61850
(Dual SC Fiber)
REQUIREMENT
B
Sensitive earth-fault current detection (30 A primary).
0=Normally Open
1=Normally Closed
Specifications
Input Voltage
Dimensions
GF Trip-Level Settings
GF Trip-Time Settings
Vn Trip-Level Settings
Output Contacts
Operating Mode
Harmonic Filtering
Reset
Approvals
Communications
Analog Output
Conformal Coating
Warranty
Mounting
See ordering information
H
213 mm (8.4”),
W
98 mm (3.9”),
D
132 mm (5.2”)
0.125 to 30 A
0.1 to 0.5 s
20-2,000 Vac (≤5 kV systems)
100-10,000 Vac (>5 kV systems)
Two Form A, Two Form C
Fail-Safe
Standard feature
Front panel push button and remote input
C-Tick (Australian), CE
Mini USB (standard); DeviceNet (optional), IEC 61850
(optional), Modbus TCP and EtherNet/IP (optional)
ACCESSORIES
ER Series Sensing Resistor
Current Transformer
SE-IP65CVR-G
SE-MRE-600
RK-332
Required
Required
Optional
Optional
Optional
4-20 mA, self or loop powered
Standard feature
5 years
Panel, Surface (optional)
© 2015 Littelfuse Protection Relays & Controls
Littelfuse.com/se-330au
Rev: 4-D-092915
Based on Manual Rev: 4-E-091115
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