SE-330 Series

Neutral-Grounding-Resistor Monitor

We're here to help

Talk to an expert today.
Our friendly team of highly trained specialists will quickly assist you.

Get a quote technical support 1300 387 326

Description

The SE-330 is an advanced ground-fault and neutral-groundingresistor 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.

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.

Ground-Fault Monitoring

The SE-330 uses an application-appropriate current transformer to reliably detect ground-fault currents as small as 100 mA. DiscreteFourier Transform (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.

Pulsing Ground-Fault Location

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.

How to monitor NER integrity 

Features & Benefits

  • Continuous NGR monitoring

    Detects resistor failure within seconds, reduces transient-overvoltage risk, removes risk of ground-fault-detection failure

  • Shorted NGR detection

    Detects a ground fault on the neutral that could bypass the resistor, ensures fault current is not higher than expected

  • Ground-fault detection

    Main or backup protection to detect a ground fault anywhere on the monitored system

  • Adjustable pickup (2-100%)

    Select greatest sensitivity without false operation, adjustable in 1% increments (MEM setting)

  • Adjustable time delay (0.1-10 s)

    Adjustable trip delay allows quick protection and system coordination

  • Universal CT compatibility

    Allows the use of a CT that gives required ground-fault settings

  • Programmable output contacts

    Two programmable Form C and One programmable Form A (Ground Fault, Resistor Fault, Unit Health)

  • Selectable contact operating mode

    Selectable fail-safe or non-fail-safe operating modes allows connection to shunt or undervoltage breaker coil or alarm circuit (K1, K2, and K3 output contacts)

  • Analog output (4-20 mA)

    Connect an optional PGA-0520 meter or control system

  • Pulsing output (SE-330 only)

    Control the operation of a pulsing ground-fault-location circuit

  • Trip records

    On-board 100-event (with date and time) recorder helps with system diagnostics

  • Harmonic filtering (DFT)

    Eliminate false trips due to harmonic noise from ASDs

  • Local communications

    Mini USB port to view measured values, configure settings, and check event records

  • Data logging

    On-board microSD card (included) can be used for long-term data logging

  • Network communications 

    Remotely view measured values and event records, reset trips, and cause a remote trip
    Available Protocol Options: IEC 61850 - with dual RJ45, SC Fiber and RJ45, or Dual SC Fiber Interface Modbus TCP and Ethernet/IP - with dual RJ45, SC Fiber and RJ45, or Dual SC Fiber Interface DeviceNet - with CAN interface

  • Software

    PC-interface software (SE-MON330) is available at Littelfuse.com/RelaySoftware

  • Selectable reset mode

    Selectable latching or auto-reset operation

  • Unit-healthy output

    Verifies SE-330 is operating correctly, available as Form A or Form B output contact

  • Conformal coating

    Internal circuits are conformally coated to protect against corrosion and moisture


Datasheets & Manuals

SE-330 Datasheet

SE-330 Manual 

SE-330 DeviceNet Manual 

SE-330 Profibus Manual 

SE-330 EthernetIP Manual 

SE-330 Firmware Update Instructions

White Paper - Neutral Earthing Resistor Monitoring

Video


Specifications

  • IEEE Device Numbers: Ground Fault (50G/N, 51G/N, 59N), Checking Relay (3), Lockout Relay (86)
  • Input Voltage: See ordering information
  • Dimensions: H 213 mm (8.4"); W 98 mm (3.9"); D 132 mm (5.2")
  • GF Trip-Level Settings: 2-100% of CT-Primary Rating in 1% increments
  • GF Trip-Time Settings: 0.1-10 s
  • Vn Trip-Level Settings: 20-2,000 Vac (≤5 kV systems) 100-10,000 Vac (>5 kV systems)
  • Contact Operating Mode: Selectable fail-safe or non-fail-safe (K1, K2, K3)
  • Harmonic Filtering: Standard feature
  • Reset Button: Standard feature
  • Output Contacts: Two Form A and two Form C
  • Pulsing Circuit: 1.0-3.0 s in 0.2 s increments (SE-330 only)
  • Approvals: CSA certified, UL Listed (E340889), CE (European Union), RCM (Australian)
  • Communications: Mini USB (standard); DeviceNet (optional), IEC 61850 (optional), Modbus TCP and EtherNet/IP (optional)
  • Analog Output: 4-20 mA, self or loop powered
  • Conformally Coated: Standard feature
  • Warranty: 5 years
  • Mounting: Panel and Surface (optional)



Ordering Information

ORDERING NUMBERPOWER SUPPLYCOMMK4 UNIT HEALTHY CONTACT
SE-330XXX
SE-330 for applications 35 kV or less

SE-330HV for 72 kV applications
0=120/240 VAC/VDC
2=48 VDC
0=USB Only 1=DeviceNet 3=EtherNet (Dual RJ45) 4=EtherNet (SC Fiber & RJ45) 5=EtherNet (Dual SC Fiber) 6=IEC61850 (Dual RJ45) 7=IEC61850 (SC Fiber & RJ45) 8=IEC61850 (Dual SC Fiber)

0=Normally Open 1=Normally Closed



ACCESSORIESREQUIREMENT
ER Series Sensing ResistorRequired
Current TransformerRequired
SE-IP65CVR-GOptional
SE-MRE-600Optional
RK-332Optional
NGRM-ENCOptional
PGA-0520Optional
SE-330-SMAOptional



Accessories

ER Series Sensing Resistor
Required interface between the power system and the SE-330/SE-330HV. Eliminates hazardous voltage levels at the relay.

ELCT5 Series Ground-Fault Current Transformer
Sensitive ground-fault current detection (5 A primary).

ELCT30 Series Ground-Fault Current Transformer
Sensitive ground-fault current detection (30 A primary).

Other Current Transformer
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 Hinged Transparent Cover
Watertight cover, tamper resistant, IP65 protection.

Featured Case Study

Dugald River Zinc Mine

The Dugald River zinc-lead-silver mine is situated 65km north-west of Cloncurry in Northern Queensland, Australia, and owned by MMG. It is one of the world’s biggest zinc-lead-silver deposits and comprises of high-grade minerals. Dugald River ore is mined underground using diamond drilling techniques, after which it is extracted to the surface and treated on-site. Concentrate is then transported to the Port of Townsville via rail departing from Cloncurry.

We're here to help

Talk to an expert today.
Our friendly team of highly trained specialists will quickly assist you.

Get a quote technical support 1300 387 326

We promise to respond within 4 business hours (AEST).

Or you will receive $100 off your next purchase. Read how it works.

Ribbon with dollar sign drawn in bold orange lines

Premium brands

Our brands are carefully selected and have a great track record of quality, reliability and safety.

Icon for transport shows drawing of truck in motion drawn in orange bold lines.

Years of experience

Since being established in 1996, our company has been synonymous with great customer service.

Happy face with bangs logo drawn in thick orange line.

Customers served daily

Fuseco has strong relationships with many clients from a wide range of industries.

Clock showing 4 o'clock drawn in thick orange line.

Reply in 4 Hours

You will receive $100 off your next purchase if we do not reply within 4 business hours (AEST).

Related Resources

Fuseco supplies cutting-edge relay solutions from Littelfuse.
The Dugald River Zinc Mine, located in the north-west of Cloncurry in Northern Queensland, and owned by MMG, had Neutral Earthing Resistor’s installed on site and they were doing annual periodic maintenance checks to verify NER resistance and integrity during shutdowns.
A motor protection relay is designed to help protect motors from overloads, jams, phase loss or unbalance, heat, heavy start-ups or excessive operational cycles.
Clever yet very simple and cost-effective steps can be taken today, to improve the electrical safety of old switchboards in use across the country, lacking modern protection against arc-fault events.
The Littelfuse EL731 series is a new and sensitive Earth Leakage Technology – the first of its kind to offer complete coverage of all frequencies from 0(DC) to 6,000Hz, including DC earth leakage typical for VSD applications.
Had this relay not been there, they were looking at between $800,000 to $1 million in damages.
A Neutral Earthing Resistor (NER) plays an important role in an electrical environment and is one of the most effective ways to maximise personnel safety. Continual monitoring is imperative to detect resistor failure with or without an earth fault present.
The MP8000 dramatically increases motor protection, resulting in longer motor life plus reduced downtime and repair costs.
Protect your People. Protect your Equipment.
Littelfuse Protection Relay and Arc-Flash FAQ
Littelfuse White Paper -Key Considerations for selecting-Arc-Flash
Littelfuse Protection Relays AF0100 Generator Application Guide
Littelfuse PGR-8800 Application Guide
Littelfuse AF-0500 Application Guide
Littelfuse Diagram -Protect Your Wind Turbine From Arc-Flash hazards
A new approach to mining earth leakage protection with medium voltage drives

Top FAQs

A protection relay is a device that receives inputs typically from current transformers CT’s (but can be other sources) and then compares these inputs to set levels. If these inputs exceed the set levels a protection relay can then provide that information via display or indication, feed that information to other electronic control devices or it can be connected to a circuit breaker to isolate power.

Yes, currently Fuseco can offer both earth leakage and NER relays that are compliant to AS2081:2011. The relay manufacturer (Littelfuse) is also currently in the final stages of development for an AS2081:2011 compliant continuity relay that we expect to release in the near term.

An arc fault is a type of electrical fault that results from the breakdown of an insulating medium between two conductors where the energy is enough to sustain an arc across the insulator (often air) and can cause extreme amounts of light (arc flash), immense heat upwards of 19,000 degrees, and a resulting explosive pressure wave (arc blast). By using a relay that has optical sensors we can detect the flash of light the emanates from an Arc Flash and within 1 msec send a signal to a breaker to interrupt power. Because of the immense energy being released by an Arc Flash reaction time is critical. It can be seen on the graph that with a relay reaction time of only 1 msec (+ circuit breaker reaction time) we can interrupt power before the Arc Flash can result in critical damage.

An arc-flash happens when electric current flows through an air gap between conductors. There are several ways this can happen but the most common occurrence is when conductor insulation is worn or broken down.

The most important aspects of arc-flash relays are:


  • reaction time
  • trip reliability
  • ease of installation
  • sensor flexibility
  • software
  • sensor design
  • avoidance of nuisance tripping
  • scalability


To gain a deeper understanding of which features to consider when selecting an arc-flash relay please refer to the downloadable application guides.

Arc-flash relays are a necessary component in an electrical cabinet because they reduce the amount of incident energy in the system. While an arc-flash relay cannot prevent an arc flash from happening, it will protect critical assets and workers’ safety by reducing the severity of the flash. An arc-flash relay is an integral part of an arc-flash protection scheme that can minimize damage, and save money, time, and lives.

Three phase power systems are most often solidly earthed, however by using a Neutral Earthing Resistor (NER) a power system can be resistance earthed. This is done so that if an earth fault were to occur the amount of fault current will be limited by the NER resistance. One potential problem with a resistance earthed system is; what happens if the NER goes open circuit due to damage? If this were to happen the power system has now changed from a resistance earthed system to a system with no earth reference (floating). Now the NER is no longer restricting the amount of fault current and other devices that rely on an earth reference in order to operate, cannot do so. By using a NER monitoring relay the resistance and integrity of a NER can be continually monitored to detect for any variance in the NER resistance or integrity.

An earth fault can occur as a result of inadvertent contact between and energized conductor and earth or equipment frame. There can also be earth leakage from a system without “inadvertent contact”. This type of fault can be called capacitive earth leakage and it is caused by a capacitive effect between a high power conductor and earth. Small amount of earth leakage current can occur as a result of this capacitive effect. Whether it is smaller amounts current from capacitive earth leakage or larger amounts of current from direct inadvertent contact an earth leakage relay can detect this fault current. In all electrical circuits, current returns to its source. An earth fault relay can use a zero sequence CT to monitor phase current to ensure that all current coming from the source returns on those same conductors or it can monitor current in the connection between transformer neutral and earth. By either method the earth leakage relay detect any lost current to earth.

our brand portfolio

Littelfuse logo in green on white background

Applicable Industries

Hi Tim, just wanted to thank you and the Fuseco team for your help. You've managed to help us solve some nagging issues here and the Littelfuse SE-330AU relay installation has saved us a lot of time. Thanks!

Mark Sherman

PGS Silver, Queensland

Just wanted to send a note of thanks to you guys. When it comes to relays, your advice & service is high level & appreciated. Cheers.

Jesse Marshall

Newcrest WA

The Littelfuse SE-701 & the CT's are functioning well. Thanks guys, really appreciate your help. Good to work with people you can rely on.

Cliff Peligro

Alpha Coal, Queensland

Technical Support

Our experts are all pre-eminent leaders in electrical products who provide excellent support in their areas of expertise.

Technical support

Talk to an expert

Our friendly team are highly trained product experts who really enjoy helping customers find what they need.

1300 387 326

call 1300 387 326

Enquire by email

We promise to respond within 4 business hours (AEST) or you will receive $100 off your next purchase.

Enquire now