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Neutral Grounding Resistors

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Features and Options

Resistive Elements
Wirewound resistive elements consists of an open helical stainless steel wire wrapped around a tubular porcelain core, allowing for fast and efficient cooling. In general wirewound resistive elements are ideal for low current conditions, offering excellent power dissipation, stable resistance, and shock-proofing.

wirewound-cutout-2

Edgewound resistive elements are strip type elements, essentially a stainless steel tape wound on tubular porcelain insulators. A rod is placed inside these resistive elements to form the resistive assembly. They are used in general for medium-level currents, touting shock-proofing, and compactness.

DSCN0507

Generally used for low resistance and high current, grid resistors are made with punched steel sheet with holes at in each end for mounting. Grids are then stacked on insulated steel rods. Mica washers are inserted between grids for insulation, and the rods are mounted between steel end frames. To obtain the best electrical connection, we weld grids together.

MegaResistors Stamped Grid Resistor

Enclosures
Enclosures constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt).

IP20
Protected against solid foreign objects of 12.5mm in diameter and greater. Not protected against water ingress.

MegaResistors NEMA 1

Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain , sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.

IP23
Protected against solid foreign objects of 12.5mm in diameter and greater.
Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.

MegaResistors NEMA 3R

Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); and that will be undamaged by the external formation of ice on the enclosure.

IP56
Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact.
Water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects.

MegaResistors NEMA 4

Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose directed water); that provides an additional level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure.

IP56
Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact.
Water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects.

MegaResistors NEMA 4

Enclosure Materials
A protective coating of zinc is applied to steel. The zinc provides cathodic protection due to its greater negative electrochemical potential, making it the metal of preference to be consumed (when rusting). It often shows an aesthetic feature known as spangle, crystallites inside the coating. All of our galvanized steel material meets specific ASTM coating standards.

Once the galvanized steel is prepared, it is then treated for painting with a non-metallic iron phosphate coating. This heavily improves paint adhesion and increases corrosion protection if the metal’s paint film is broken. After the steel has been phosphatized, it is then powder coated. Powder coating cures in heat, forming a “skin”. This creates a harder finish, tougher than conventional paint.

Galvanized steel is a generally cost-effective and reliable material to prevent corrosion and damage to your product.

Galv Steel

The most widely used stainless steel is the “304″ type, comprised of 18% chromium and 8% nickel. We also offer “316″ grade stainless steel, comprised of 18% chromium and 10% nickel.

Stainless steel is touted for its resistance to corrosion and staining, and low maintenance needs. If your product will be used in an environment subject to corrosive conditions then we recommend using stainless steel over galvanized steel. The 304 grade steel provides greater resistance to corrosion than galvanized steel, and the 316 grade steel provides even more resistance than the 304.

Because stainless steel is comprised of chromium and nickel throughout the material itself, it provides corrosion resistance for a longer duration as it does not rely on a coating for protection. This leaves painting to be an an optional layer of protection. We generally use stainless steel with a natural finish unless otherwise specified.

If you need the high corrosion resistance paired with long-term usage, then consider stainless steel as a very viable alternative to galvanized steel.

SS

Anodizing is a process used to increase the thickness of a natural oxide layer formed on the surface of metal. Aluminum when exposed to any gas containing oxygen at room temperature will form a surface layer of amorphous aluminum oxide, which is very effective against corrosion.

We recommend anodized aluminum if you have specific corrosive conditions that are not or cannot be met by stainless steel. It is a very effective method of protecting against certain corrosive conditions.

anod alum

Enclosure Mounting
Every enclosure comes with standard floor mounting. The bottom of the enclosure is used to mount it to a surface below it.

floormount

Optionally enclosures can be mounted against a wall. Special brackets may be required for some enclosures.
Enclosure Attachments
An optional door for the enclosure for easy access to the resistive circuit, this features a lock as well for security purposes.

Door w/ Lock

Tamperproofing enclosures ensures that they cannot be opened by unauthorized personnel, as they require special equipment to open.

Shipping Special Bracing is an added bracing between the resistive circuit components and the enclosure to ensure that the resistive circuit is not damaged during the shipping process.

Seismic zone special bracing

Transformers
IEEE 600V
Model Window Diameter Application
21-25 1.25″, 1.63″, 2.00″, 2.50″, 3.13″ Metering and Relaying
296-300 1.50″, 2.25″, 3.00″, 3.38″, 3.75″ Metering and Relaying
112-117 2.25″, 2.75″, 3.25″, 4.00″, 4.62″ Metering and Relaying
115MR 4.00″ Relaying
117MR 4.62″ Relaying
200-204 2.50″, 3.50″, 4.88″, 5.25″, 4.50″ Metering and Relaying
100 4.00″ Metering and Relaying
110 4.00″ Metering and Relaying
137 5.50″ Metering and Relaying
130 5.75″ Metering and Relaying
145 6.00″ Metering and Relaying
780 6.50″ Metering and Relaying
781 6.50″ Metering and Relaying
785 6.50″ Metering and Relaying
786 6.50″ Metering and Relaying
680 7.02″ Metering and Relaying
681 7.02″ Metering and Relaying
685 7.02″ Metering and Relaying
143 7.31″ Metering and Relaying

Because this list of products is not exhaustive, we suggest browsing the catalog on GE’s website for this type of transformer. You can visit their catalog here.

IEEE 5 to 35kV
Model Voltage Class Application
CTW3T10 5 kV, 60 kV BIL Metering and Relaying
CTW3T50 5 kV, 60 kV BIL Metering and Relaying
CTWH3T100 5 kV, 60 kV BIL Metering and Relaying
CTWH3AT90 5kV, 60kV BIL High accuracy Metering and Relaying
CTWH4T100 8.7 kV, 75 kV BIL Metering and Relaying
CTW5L 15 kV, 110 kV BIL Metering and Relaying
CTWH5T200 15 kV, 110 kV BIL Metering and Relaying
CTWH5AT150 15kV, 110kV BIL High accuracy Metering and Relaying
CTWH5S 15kV, 110kV BIL For switchgear, extra high short circuit strength
CTW6 25 kV, 125 kV BIL Metering and Relaying
CTWH6 25 kV, 125 kV BIL Metering and Relaying
CTW7 34.5kV, 150 kV BIL Metering and Relaying
CTWH7 34.5 kV, 150 kV BIL Metering and Relaying
IEC 720V
Model Voltage Class Application
GA 720V Instrumentation and Metering
21I-25I 720V Relaying and Metering
296I-300I 720V Relaying and Metering
680I 720V Protective and Measuring
685I 720V Protective and Measuring
780I 720V Protective and Measuring
785I 720V Protective and Measuring
Information
Current transformers (CT) are used to measure alternating electric currents. Current transformers are classified as instrument transformers, designed to have negligible load on the supply being measured, and provide an accurate current ratio and phase relationship. These are used to enable connected metering (for example protective relays or ammeters).  The current transformer safely isolates measurement and control circuitry from the high voltages typically present on the circuit being measured.

Current transformers are often constructed by passing a single primary turn (either an insulated cable or an uninsulated bus bar) through a well-insulated toroidal core wrapped with many turns of wire. The CT is typically described by its current ratio from primary to secondary. For example, a 4000:5 CT would provide an output current of 5 amperes when the primary was passing 4000 amperes. The secondary winding can be single ratio or have several tap points to provide a range of ratios. Care must be taken that the secondary winding is not disconnected from its load while current flows in the primary, as this will produce a dangerously high voltage across the open secondary and may permanently affect the accuracy of the transformer.

Current Transformer Ratio Modification Techniques:

Relatively large changes in a CT ratio may be achieved through the use of “Primary Turns”. 1 Primary Turn = 1 pass through the Current Transformer window. More than 1 pass through results in the electrical ratio modification. For Example:

CT Ratio
Normal 1 Pass
Number of Primary Turns Modified Ratio
 100:5A  2  50:5A
 200:5A  2  100:5A
 300:5A  2  150:5A
 100:5A  3  33.3:5A
 200:5A  3  66.6:5A
 300:5A  3  100:5A
 100:5A  4  25:5A
 200:5A  4  50:5A
 300:5A  4  75:5A

A “Primary Turn” is the number of times the primary conductor passes through the CT’s window. The main advantage of this ratio modification is you maintain the accuracy and burden capabilities of the higher ratio. The higher the primary rating the better the CT accuracy and burden rating.

Current Transformer

IEEE 600V
Model Phase Accuracy ; Thermal Rating
467 Single 1%@ 5 VA ; 40VA
468 Single 0.6%@ 7.5 VA ; 75VA
460 Single 0.6W, 1.2 X ; 150VA
460F & 460FF Single 0.6W, 1.2 X ; 150VA
465 Single 0.3W, 0.6 X, 1.2M ; 300VA
475 Single 0.3WXMY, 1.2Z ; 750VA
450 Single 1% @ 5 VA ; 40VA per phase
2VT469 Three 1% @ 5VA ; 40 VA per phase
3VT472 Three 0.6% @7.5VA ; 75 VA per phase
3VT468 Three 0.6W, 1.2X ; 150 VA per phase
2VT460 Three 0.6W, 1.2X ; 150 VA per phase
3VTN460 Three 0.6W, 1.2X ; 150 VA per phase
3VTL460 Three Multiple accuracies
JVA-0C Three Multiple accuracies
JE-27C Three Multiple accuracies
JEV-0C Three Multiple accuracies
JVM-0C Three Multiple accuracies
IEEE 5 to 35kV
Model Voltage Class Accuracy
3PT3 5kV, 60kV BIL 0.3WX, 0.6M, 1.2Y
PT3 5kV, 45kV BIL 0.3WX, 0.6MY, 1.2Z
PTG3 5kV, 60kV BIL 0.3WXMY, 1.2Z
PTW3 5kV,60kV BIL 0.3WXMY, 1.2Z
PTG4 8.7kV, 75kV BIL 0.3WXMYZ, 1.2ZZ
PTW4 8.7 kV,75 kV BIL 0.3WXMYZ, 1.2ZZ
PTG5 15 kV, 110 kV BIL 0.3WXMYZ, 1.2ZZ
PTW5 15 kV,110 kV BIL 0.3WXMYZ, 1.2ZZ
PT6-1 25 kV,125 kV BIL 0.3WXMYZ, 1.2ZZ
PT6-2 25 kV, 125 kV BIL 0.3WXMYZ, 1.2ZZ
PT7-1 34.5 kV, 200 kV BIL 0.3WXMYZ, 1.2ZZ
PT7-2 34.5kV, 200kV BIL 0.3WXMYZ, 1.2ZZ
JVM-2C_3C 2400-4800V 60kV BIL Multiple accuracies
JVM_4A_5A 4200-14400V 75-110kV BIL Multiple accuracies
JVM-4C_5C 4200-14400V 75-110kV BIL Multiple accuracies
JVM-4AC_5AC 4200-14400V 75-110kV BIL Multiple accuracies
JVM-6C 12000-24000V 125kV BIL Multiple accuracies
IEC 720V
Model Voltage Class Accuracy
450I 720V 0.2 @ 40VA, 0.5 @ 70VA
460I 720V 0.5 @ 10VA, 1.0 @ 20VA
460IF & 460IFF 720V 0.5 @ 10VA, 1.0 20VA
475I 720V 0.2 @ 10VA, 0.5 @ 20VA
Information
Potential transformers (PT) are used to measure alternating electric currents. Potential transformers are classified as instrument transformers, designed to have negligible load on the supply being measured, and provide an accurate voltage ratio and phase relationship. These are used to enable connected metering (for example protective relays or voltmeters). Typically the secondary of a voltage transformer is rated for 69 V or 120 V at rated primary voltage, to match the input ratings of protective relays.

The transformer winding high-voltage connection points are typically labeled as H1, H2 (sometimes H0 if it is internally grounded) and X1, X2 and sometimes an X3 tap may be present. Sometimes a second isolated winding (Y1, Y2, Y3) may also be available on the same voltage transformer. The high side (primary) may be connected phase to ground or phase to phase. The low side (secondary) is usually phase to ground.

The terminal identifications (H1, X1, Y1, etc.) are often referred to as polarity. This applies to current transformers as well. At any instant terminals with the same suffix numeral have the same polarity and phase. Correct identification of terminals and wiring is essential for proper operation of metering and protective relays.

Some meters operate directly on the secondary service voltages at or below 600 V. VTs are typically used to reduce higher voltages or where isolation is desired between the meter and the measured circuit.

Potential Transformer

Zigzag transformers are special purpose transformers with a zigzag or interconnected star winding connection. It is used to create a missing neutral connection from 3-phase systems without a ground. A neutral connection is required for an NGR.

Step down transformers reduce electrical voltage. This is used commonly when low voltage instruments are to be connected directly to the resistor.

Sensing Resistors
Attached in parallel to the resistor circuit, the sensing resistor will allow a protective relay to detect a resistor failure.

Sensing Resistor

Protection Relays
Description
A protection relay is a smart device that receives inputs, compares them to set points, and provides outputs. Inputs can be current, voltage, resistance, or temperature. Outputs can include visual feedback in the form of indicator lights and/or an alphanumeric display, communications, control warnings, alarms, and turning power off and on.

Protection relays can be either electromechanical or electronic/microprocessor-based. Electromechanical relays are an obsolete technology consisting of mechanical parts that require routine calibration to stay within intended tolerances. Microprocessor or electronic relays use digital technology to provide quick, reliable, accurate, and repeatable outputs. Using an electronic or microprocessor-based relay instead of an electromechanical design provides numerous advantages including improved accuracy, additional functions, reduced maintenance, smaller space requirements and lifecycle costs.

 

 

Inputs: A relay needs information from the system to make a decision. These inputs can be collected in a variety of ways. In some cases, the wires in the field can be connected directly to the relay. In other applications, additional devices are needed to convert the measured parameters to a format that the relay can process. These additional devices can be current transformers, potential transformers, tension couplers, RTDs or other devices.

 

Settings: Many protection relays have adjustable settings. The user programs settings (pick-up levels) that allow the relay to make a decision. The relay compares the inputs to these settings and responds accordingly.

 

Processes: Once the inputs are connected and the settings are programmed, the relay compares these values and makes a decision. Depending on the need, different types of relays are available for different functions.

 

Outputs: The relay has several ways of communicating that a decision has been made. Typically the relay will operate a switch (relay contact) to indicate that an input has surpassed a setting, or the relay can provide notification through visual feedback such as a meter or LED. One advantage of electronic or microprocessor relays is an ability to communicate with a network or a PLC.

SE-701
Functions:
  • Ground-fault protection for resistance- and solidly grounded three-phase systems
  • Ground-fault protection on single-phase systems
  • Main, feeder, or load protection
  • Can reduce equipment damage and down time
Features:
  • Microprocessor based – recalibration not required
  • DFT (harmonic) filter prevents false operation
  • Compatible with adjustable-speed drives and soft starters
  • Self-test function
  • 0- to 5-V analog output for external metering
  • Selectable fail-safe (undervoltage) or non-fail-safe (shunt) operating mode
  • Remote reset and indication
  • Non-volatile trip memory
  • Current-sensor verification
  • DIN-rail, surface, and panel mounting
  • Five year warranty
Typical Applications:
  • Used on feeders, motors, generators, heating cable, SCR-controlled heaters, and ASD’s
  • Retrofit and upgrade applications using existing CT’s
Minimum System Components:
  • The SE-701 requires an EFCT-series current sensor or a 1- or 5-A-secondary CT.
IEEE Device Numbers:
  • 50G, 50N, 51G, 51N
SE-704
Functions:
  • Ground-fault protection for resistance-grounded three-phase Systems
  • Ground-fault protection on single-phase systems
  • Main, feeder, or load protection
  • Can reduce equipment damage and down time
Features:
  • Microprocessor based – recalibration not required
  • DFT (harmonic) filter prevents false operation
  • Compatible with adjustable-speed drives and soft starters
  • Self-test function
  • 0- to 5-V analog output for external metering
  • Selectable fail-safe (undervoltage) or non-fail-safe (shunt) operating mode
  • Remote reset and indication
  • Non-volatile trip memory
  • Current-sensor verification
  • DIN-rail, surface, and panel mounting
  • Ground-fault trip level is 10 to 5,000 mA
  • Five year warranty
Typical Applications:
  • Used on feeders, motors, generators, heating cable, SCR-controlled heaters, and ASD’s.
Minimum System Components:
  • The SE-704 requires an SE-CS30-series current sensor.
IEEE Device Numbers:
  • 50G, 50N, 51G, 51N
SE-325
Functions:
  • Detects neutral-grounding-resistor failure – NGR failure will render current-sensing ground-fault protection inoperative
  • Detects ground faults
Features:
  • Continuously monitors NGR continuity
  • Conforms to CSA Standard M421-00 Use of Electricity in Mines
  • Meets the requirements of the Pennsylvania Bureau of Mine Safety
  • Provides main or backup ground-fault protection
  • Trip delay to coordinate with downstream ground-fault relays
  • Selectable fail-safe (undervoltage) or non-fail-safe (shunt) operating mode
  • LED indication of Ground Fault, Resistor Fault, and Power
  • Conformally coated circuit boards
  • Five year warranty
Typical Applications:
  • Transformers and generators with a maximum 25-A NGR in processing, manufacturing, chemical, mining, forestry, petroleum, and water-treatment facilities
  • NGR monitoring is recommended for all resistance-grounded systems
  • Can be used with a zigzag transformer and an NGR to provide monitored resistance grounding to upgrade an ungrounded supply
  • Pulsing ground-fault location systems
Minimum System Components:
  • The SE-325 requires a CT200 current transformer and a sensing resistor (ER-600VC, ER-5KV, ER-15KV, or ER-25KV).
  • Outdoor Sensing Resistor Applications
IEEE Device Numbers:
  • 50G, 50N, 51G, 51N, 59N, 86
SE-330HV
Functions:
  • Detects neutral-grounding-resistor failure – NGR failure will render current-sensing ground-fault protection inoperative
  • Detects ground faults
  • Controls pulsing-ground-fault system
  • Data logging with PC software
Features:
  • Continuously measures NGR resistance
  • Wide set-point ranges – compatible with any neutral-connected NGR up to 72-kV system voltage
  • Calibrates to NGR resistance
  • 4-20 mA output for earth-leakage metering
  • DFT (harmonic) filter prevents false operation
  • Trip delay to coordinate with downstream ground-fault relays
  • Standard RS-232 interface
  • Optional DeviceNet, PROFIBUS, and Ethernet communications
  • Four output relays for control and indication
  • Pulsing output contact for fault locating
  • Conforms to CSA Standard M421-00 Use of Electricity in Mines
  • Free SE-MON330 PC-interface software
  • Conformally coated circuit boards
  • Five year warranty
Typical Applications:
  • Resistance-grounded transformers and generators in processing, manufacturing, chemical, mining, forestry, petroleum, and water treatment facilities
  • Tripping and alarm-only resistance-grounded systems, including overhead line and pulsing-ground-fault applications
  • Compatible with very high and very low resistor values
  • NGR monitoring is recommended for all resistance-grounded systems
Minimum System Components:
  • The SE-330 requires a current transformer and a sensing resistor (ER-600VC, ER-5KV, ER-15KV, ER-25KV, or ER-35KV).
  • Outdoor Sensing Resistor Applications
IEEE Device Numbers:
  • 50G, 50N, 51G, 51N, 59N, 86

 

 

SE-330HV
Functions:
  • Detects neutral-grounding-resistor failure – NGR failure will render current-sensing ground-fault protection inoperative
  • Detects ground faults
  • Data logging with PC software
Features:
  • Continuously measures NGR resistance
  • Wide set-point ranges – compatible with any neutral-connected NGR up to 72-kV system voltage
  • Calibrates to NGR resistance
  • 4-20 mA output for earth-leakage metering
  • DFT (harmonic) filter prevents false operation
  • Trip delay to coordinate with downstream ground-fault relays
  • Standard RS-232 interface
  • Optional DeviceNet, PROFIBUS, and Ethernet communications
  • Four output relays for control and indication
  • Conforms to CSA Standard M421-00 Use of Electricity in Mines
  • Free SE-MON330 PC-interface software
  • Conformally coated circuit boards
  • Five year warranty
Typical Applications:
  • Resistance-grounded transformers and generators in processing, manufacturing, chemical, mining, forestry, petroleum, and water treatment facilities
  • Tripping and alarm-only resistance-grounded systems, including overhead line and pulsing-ground-fault applications
  • Compatible with very high and very low resistor values
  • NGR monitoring is recommended for all resistance-grounded systems
Minimum System Components:
  • The SE-330HV requires a current transformer and a sensing resistor (ER-15KV, ER-25KV, ER-35KV, or ER-72KV).
  • Outdoor Sensing Resistor Applications
IEEE Device Numbers:
  • 50G, 50N, 51G, 51N, 59N, 86
Bushings
Electrical bushings are used to provide neutral or ground connection terminals outside the enclosure. A Top Neutral bushing is situated on the top of the enclosure.

 

Bushing

Electrical bushings are used to provide neutral or ground connection terminals outside the enclosure. A Side Neutral bushing is situated on the side of the enclosure.

 

Bushing

Electrical bushings are used to provide neutral or ground connection terminals outside the enclosure. A Top Ground bushing is situated on the top of the enclosure.

 

Bushing

Electrical bushings are used to provide neutral or ground connection terminals outside the enclosure. A Side Ground bushing is situated on the side of the enclosure.

 

Bushing

Pulsing System
Pulsing is a feature that introduces a pulse to to the resistive circuit, allowing a technician to easily determine the spot where a ground fault is occurring. Pulsing can only be used in High Resistance Grounding.
Measuring Devices
An ammeter is a measuring instrument used to measure electric current. Some resistors include ammeters so you can easily check the current running in the resistive circuit. A metering current transformer is required with the appropriate ratio to provide accurate readings.
A voltmeter is a measuring instrument used to measure electrical potential difference. Some resistors have voltmeters so you can easily check the voltage across the resistive circuit; Potential transformers with the appropriate ratio are required for accurate readings.
Other Optional Features
  • Disconnect Switch: turn off the resistive circuit at any time
  • Heater with Thermostat: in humid environments, prevents the condensation of water into the system

What are Neutral Grounding Resistors?

The purpose of a neutral grounding resistor is to limit ground fault currents to safe levels so that all the electrical equipment in a power system is protected. The resistor should be the only current path between the neutral of power transformers or power generators and ground.

When the neutral of a system is not grounded it is possible for destructive transient overvoltages to appear from line to ground during normal switching of a circuit having a line-to-ground fault. Experience has proved that these overvoltages cause aging and failure of insulation at locations on the system other than at the point of fault. In this way, a relatively unimportant line-to-ground fault on one circuit may result in considerable damage to equipment and interruption of service on other circuits, not to mention the increased difficulty in finding the original location of the problem.

A neutral grounding resistor is designed to limit the ground fault current to a safe value while at the same time letting enough current to flow to operate the protective relays that will alarm or clear the fault. While the disturbance lasts the resistor must be capable of absorbing and dissipating the energy generated without exceeding the temperature limits established by IEEE-32 Standards. In this way the fault is safely limited, isolated, and the power system is protected against over-voltages.

Neutral Grounding Resistors are also commonly referred to as Neutral Earthing Resistors and Earth Fault Protection.

High Resistance or Low Resistance?

High Resistance Grounding Resistors are recommended for installations that require continuous service even after a phase ground fault occurs.

A phase to ground fault will not cause a large current to flow and will not trip the breakers because the neutral grounding resistor will limit the current to a very low value, typically 5 Amps.

For added security it is required that a suitable ground detection device, or ground fault relay, be used to indicate the presence of a ground fault.

Pulsing devices can be used with high resistance systems to reduce the time required to find and remove the ground fault.

This type of Neutral Grounding Resistor should limit the fault to a value greater than the capacitive charging current of the system to avoid over-voltages caused by intermittent faults. While the disturbance lasts the resistor must be capable of absorbing and dissipating the energy generated without exceeding the temperature limits established by IEEE-32 standards.

  • Reduced operation and maintenance expenses.
  • Fast isolation of the original fault.
  • Reduced transient over-voltages.
  • Reduced physical damage on the equipment at fault.
  • Simplification of ground fault location.
  • Increased life and protection of transformers, generators and related equipment.
  • Reduced frequency of faults.
  • Improved service reliability.
  • Increased protection in the use of lightning arresters.
  • Increased safety for personnel.

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    Door with Lock
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  • Customization*Extra options and features
    Space for Customer Supplied Instruments
    Heater with Thermostat
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    Potential Transformer
    Step-Down Transformer
    Zig-Zag Transformer
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    Disconnect Switch
    Pulsing System
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    SE-701
    SE-704
    SE-325
    SE-330
    SE-330HV
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