High ResisTanCe GROunding SysTems
the power to protecthigh RESISTANCEGROUNDING systemsthe power to protectProduct Guide
D, Eaton Cutler-Hammer, Siemens,Cooper PowerHi-Tech - Intel, Research in Motion,IBM Data Centre, HoneywellAerospaceGround Fault Protection1Neutral Grounding Resistors2High Resistance Grounding6Stoplight8Sleuth10Gemini12Sentinel System14Fusion18Comparative PerformanceRatingProcess Industries - Dofasco,Nestle, Johnson & Johnson, Labatts,Proctor and Gamble, BayerConsultants - SNC Lavalin, CoSyn,Fluor Daniel, Bechtel, Bantrel,Stantec, HatchMINING & automotive - Inco,Petro-chemical - Shell, Petro-Newmont, Falconbridge, GeneralMotors, Magna, Narmco, KeiperTable of ContentsCanada, Exxon-Mobil, DowChemical, Syncrude, Imperial OilMunicipal / Commercial - Royal20the power to protectOEM’s - General Electric, SquareBank, Pearson Airport, Department ofDefense, Leamington Hospital
Potential ground faults often go unnoticed and can cause havoc on plantproduction processes. Shutting down power and equipment, ground faultsdisrupt the flow of products through manufacturing processes, leading tohours or even days of lost productivity.Undetected ground faults can also pose potential health and safety risksto personnel. Ground faults can lead to safety hazards such as equipmentmalfunctions, fire and electric shock.Ground faults can cause serious damage to equipment and to your processes.During a fault condition, equipment can be damaged and processes shutdown, seriously affecting your bottom line.The concern for ground fault protection isbased on four factors:1234The majority of electrical faults include ground.The ground fault protective sensitivity can be relativelyindependent of continuous load current values and therebyhave lower pickup settings than phase protective devices.Since ground fault current are not transferred through systempower transformers the ground fault protection for eachsystem voltage level is independent This permits fasterrelaying that can be afforded by phase protective devices.Arcing ground faults that are not properly detected and clearedcan be extremely destructive.With 25 years industry experience combined with technical leadership andinvestment in new and innovative products, I-Gard has the Power to Protect.We offer a full range of neutral grounding resistors for low resistorgrounding systems and the industry’s widest range of high resistorgrounding systems.1
ngrNEUTRAL GROUNDINGResistorsI-Gard offers a complete range of Neutral Grounding Resistors from480V to 69,000 volts and utility for resistance grounding of industrialpower systems and are connected between earth ground and theneutral of power transformers, power generators or artificial neutraltransformers.Neutral Grounding Resistors are similar to fuses in that they donothing until something in the system goes wrong. Then, like fuses,they protect personnel and equipment from damage. Damage comesfrom two factors, how long the fault lasts and the fault magnitude.Ground fault relays trip breakers and limit how long a fault lasts basedon current. Neutral grounding resistors limit the fault magnitude.The I-Gard Neutral Grounding Resistor with integralSigma Relay is the only NGR that controls both factors.Neutral Grounding resistors limit themaximum fault current to a value which willnot damage generating, distribution or otherassociated equipment in the power system,yet allow sufficient flow of fault current tooperate protective relays to clear the fault.The I-Gard SIGMA MONITOR RELAY is acombination Neutral Grounding Resistor(NGR) monitor and Ground Fault relay. Indistribution systems employing ResistanceGrounding the SIGMA MONITOR RELAYprotects against ground faults and abnormalconditions in the path between systemneutral and ground possibly caused by looseor improper connections, corrosion, foreignobjects or missing or compromised copperground wires.The SIGMA MONITOR RELAY measuresthe current through the NGR, the transformerneutral-to-ground voltage and the NGRresistance. The relay compares the measuredvalues against the field settings of therelay and provides relay outputs and LEDindications when an abnormal conditionis detected.2Why the I-Gard NGR is different:The only NGR with integral monitoring ofgrounding circuit (2400v and above models)The only NGR with integral ground faultrelay(2400v and above models)Designed with special element material withlow temperature coefficient of resistivityfor consistent fault current levelsEdgewound element design eliminates hot-spotsCSA certified and UL approved
Why consider low resistance groundedover solidly grounded?While solidly grounded systems are an improvement over ungrounded systems,and speed the location of faults, they lack the current limiting ability of resistancegrounding and the extra protection this provides. The destructive nature of arcingground faults in solidly grounded systems is well known and documented by IEEE andare caused by the energy dissipated in the fault.A measure of this energy can be obtained from the estimate of Kilowatt-cyclesdissipated in the arc: Kilowatt cycles V x I x Time (cycles) /1000100 Kilowatt Cycles Fault location identifiable at close inspection-spitmarks on metal and some smoke marks2000 Kilowatt Cycles Equipment can usually be restored by paintingsmoke marks and repairing punctures in insulation6000 Kilowatt Cycles Minimal amount of damage, but fault more easily located10,000 Kilowatt CyclesFault probably contained by the metal enclosure20,000 Kilowatt Cycles Fault probably burns through single thicknessenclosure and spreads to other sectionsOver 20,000 Kilowatt Cycles Considerable destructionThere are two broad categories of resistance grounding: low resistance and highresistance. In both types of grounding, the resistor is connected between the neutralof the transformer secondary and the earth ground and is sized to ensure that theground fault current limit is greater than the system’s total capacitance-to-groundcharging current.Low resistance grounding of the neutral limits the fault current to a high level(typically 50 amps or more) in order to operate protective fault clearing relays.These devices are then able to quickly clear the fault, usually within a few seconds.What does IEEE say about Low Resistance Grounding?IEEE Std 142-1991 Recommended Practice for Groundingof Industrial and Commercial Power SystemsClause 1.4.3 Resistance GroundingThe low-resistance method has the advantage of immediate and selectiveclearing of the grounded circuit, but requires that the minimum ground-faultcurrent be large enough to positively actuate the applied ground-fault relayIEEE Std 242-1986 Recommended Practice for the Protection andCoordination of Industrial and Commercial Power SystemsClause 7.2.3 Low-Resistance GroundingThe magnitude of the grounding resistance is selected to allow sufficientcurrent for ground-fault relays to detect and clear the faulted circuitComparison of Damage2000 kvA, 480 Volt system, single phase fault current available30,000 ampsSolidly GroundedAssumes breaker opens in 10 cycles or 0.16 seconds100 x 30,000 x 10 / 1000 30,000 KWCLow Resistance Grounded, 50 Amps 1 second100 x 50 x 60 / 1000 300 KWC3
The key reasons for limiting the fault current through resistance grounding are:To reduce burning / melting effects in faulted electrical equipment, such as switchgear, transformers,cables and rotating machinesTo reduce mechanical stresses in circuits and apparatus carrying fault currentsTo reduce electric shock hazards to personnel caused by stray ground fault currentsin the ground return pathTo reduce arc blast or flash hazard to personnel who may have accidentally caused or who happento be in close proximity to the fault currentTo secure control of transient over voltagesAll I-Gard’s low resistance grounding products are standardized on the edgewound elementdesign. Because of the rapid heating and very high temperatures encountered, this designhas been proven superior for the NGR application.The edgewound element material is mounted on porcelain supports, which are not affectedby the high temperature or high voltages. The sturdy, helically coiled element is free toexpand and does not deform when heated and offers consistent current density.The element material is critical in ensuring high operating performance of the neutralgrounding resistor. The element material is a special grade of electrical alloy with alow temperature coefficient of resistance. This prevents the resistance value fromincreasing significantly as the resistor operates through a wide temperature range.It also ensures a stable value of the fault current for proper metering and relaying.Some manufacturers offer stamped and cast alloy grids resistors for low resistancegrounding applications but the mica paper insulation they incorporate limits the temperatureat which they can operate. The mica paper insulation can also absorb moisture and failwhile the flat grid stampings may severely warp when rapidly heated. Also, the grids havehot spots which may burn when overloaded by the fault.To ensure sufficient fault current is available to positively actuatethe over-current relay and that the fault current does not decrease bymore than 20% between ambient and the full operating temperature, itis recommended that the NGR element material to be specified to havea temperature coefficient not greater than 0.0002 ohms / C.Typical NGR 8000 Volts, 1000 Amps 10 seconds, 760 C temperature rise as per IEEE 32.4Material 1AISI 304 Nickel ChromeCompetitor 1Material 2AISI 430Competitor 2Material 3Aluminum ChromeSteel 1JR (Ohmalloy)Temp Coefficientof Resistance0.001 ohms / C0.00135 ohms / C0.00012 ohms / COhms at Ambient8000 / 1000 8 ohms8000 / 1000 8 ohms8000 / 1000 8 ohmsAfter 10 Seconds8 * (1 0.001 * 760) 14.08 ohms8 * (1 0.00135 * 760) 16.21 ohms8 * (1 0.00012*760) 8.7 ohmsOperating FaultCurrent8000 / 14.08 568 amps8000 / 16.21 493 amps8000 / 8.7 919 ampsChange43.2%50.7%8.1%
SIGMATechnical SpecificationsElectrical RatingsControl Power:Maximum:Output Relay Contacts110-240V AC/DCMain Trip Relay:50/60Hz-45% to 10%5VAac or 5Wdc(60-264V AC/DC)Type:Form Z (NO and NC pair)Rating:10A@240Vac, 10A@30Vdc, 1/2HP@240VacAuxiliary Ground Fault Relay: Type:1 Form C (NO/NC)Rating: 10A@240Vac, 8A@24Vdc, 1/2HP@240VacAuxiliary NGR Fault Relay: Type:1 Form C (NO/NC)Rating: 10A@240Vac, 8A@24Vdc, 1/2HP@240VacElectrical TestsSurge test: @ 3kVDielectric test: @ 2kV for 1 minuteTemperature RangeOperating: -40 C to 60 CStorage: -50 C to 70 CPhysicalDimensions:Ground Fault CircuitCT Input:Length: 157 mm (6.18 in.)Width:Height:Weight:58 mm (2.28 in.)86 mm (3.39 in.)344 gNon-Isolated. One side of the CT input, terminal 22, is internally grounded.CT Ratio: T2A, T3A or equivalentDIP Switch SettingsTrip Level: 8 settings: 5%, 10%, 15%, 20%, 25%, 30%, 40%, and 50% of the setNGR Current SettingTrip Time: 32 settings, 0-60 msec.,150 msec. to 3.15 sec. in 100 msec. steps65287Accuracy:Repeat: 1%Trip Time: 10%, 10 msec.Trip Current: 10%Meter Output: 2% at full scale.Thermal Characteristics:Short Time Withstand 400A for 1 sec.E2223725
high resistance groundingHigh resistance grounding provides the samevoltages associated with ungrounded systems.advantages as ungrounded systems yet limitsThere is no arc flash hazard as there is with solidlythe steady state and severe transient over-grounded systems.IEEE Std 141-1993StoplightSleuthCurrent limiting resistorCurrent limiting resistorIntegral ground fault relayIntegral ground fault relayFault location through pulsingBasicHarmonic filter and time / currentadjustments to reduce false tripsIndustry StandardSafety through Innovation6At I-Gard we have the necessary highand application research, I-Gard leads the wayresistance grounding products to cover allin bringing innovative new products to marketapplications. With significant expenditurewith a commitment to reducing electricaldedicated annually to product developmenthazards.
For low voltage power distribution systems, highis proven effective in significantly reducing theresistance grounding enhances reliability andfrequency and severity of arc flash accidents.2003 IEEE IAS Safety Workshopuptime of power distribution equipment andGeminiSentinelDual path current limiting resistorCurrent limiting resistorRedundant fail-safe resistor circuitVoltage and current sensingIntegral ground fault relayIntegral ground fault relayIntegral ground monitoring relayIntegral ground monitoring relayFault location through pulsingFault location through pulsingHarmonic filter and time / currentadjustments to reduce false tripsHarmonic filter and time / currentadjustments to reduce false tripsInrush detection restraintPremiumModular and scalableMulti-feeder protectionSecond fault protectionMODBUS for remote monitoringUltra Premium7
STOPLIGHTSTOPLIGHT is a complete, inexpensive high resistance groundingsystem that provides system wide protection against damagingground faults. Using a simple but effective three light system, Stoplightprovides visual indication and available remote annunciation to informoperations and maintenance personnel of ground faults.A red light indicates an active ground fault, an amber light indicatesa ground fault has occurred but is intermittent and a green light signifiesthat there are no active ground faults on the system.Ground faults cause havoc on plantproduction processes, shutting downpower and equipment and critical loads.Ground faults disrupt the flow ofproducts through manufacturingprocesses and cause data loss incomputer centers leading to hoursor even days of lost productivity.Ground faults pose potentialhealth and safety risks to personnel,creating hazards such as equipmentmalfunctions, fire and electric shock.High Resistance Grounding (HRG) isbecoming more prevalent in industrialand commercial electrical powersystems because it eliminates unscheduled downtime due to groundfaults, and improves personnel safety bypreventing ground faults from escalatinginto arc-flash incidents. ResistanceGroundingis highly recommended for generators,to protect them from damage due toexcessive ground fault currents.8Inexpensive ground fault protection withvisual indication in NEMA 3R enclosureOptional pulsing system for easier fault locationUnique 3 light system for easy visualindication of system conditionAvailable for 480V, 600V and 4160Vdistribution systems
The four key integrated elementsTo System NeutralNo. 8 AWG Min.contained in the Stoplight system0-5Awork to protect against damagingground fault currents.0-500VAGRVYTo System GroundNo. 8 AWG Min.Schematic showsoptional pulsing1. High Resistance Grounding ResistorThis resistor is connected to the wyegenerator supplying the facility. Its functionto non-damaging levels under a singleThis provides the user an opportunity toto detect and clear the fault.point of the transformer oris to limit ground fault currentsline-to-ground fault condition.retain process continuity and2. Ground Fault Sensing Transformer and RelayThis microprocessor based digital relay measures ground fault currentusing a 1:1 zero sequence current transformer. It maintains accuracyover a range of 45Hz to 65Hz and filters out harmonics to eliminatenuisance tripping.3. Automatic Pulsing System (optional)Once the pulsing feature on the STOPLIGHT system is selected andactivated, the system will cyclically limit the fault to 100%, 75% and 50%of the available ground fault current. The cyclical pulsing combined with thehand held pulse tracing sensor empowers the user to trace the fault circuitto the point of the fault even in complex distribution systems withoutde-energizing the load.4. Hand Held Pulse Tracing Sensor (for use with optional pulsing system)This device, similar to a clamp-on ammeter, allows the user to follow thepulses from their source at the STOPLIGHT unit through to the specificlocation of the line to ground fault. Once the fault is located, it can be isolatedand repaired.65287E2223729
sleuthSLEUTHSLEUTH is a neutral grounding device that limits ground fault currentsto non-damaging levels under a single line-to-ground fault condition.SLEUTH is the ideal tool for sensing and locating ground faultsquickly and easily. When a ground fault occurs, SLEUTH controlsand limits the fault current, provides an alarm that indicates an activefault, enabling electrical personnel to follow a simple sequence tolocate and isolate the fault without interrupting the circuit or openingcircuit breakers.Ground faults cause havoc on plantproduction processes, shutting downpower and equipment and critical loads.Ground faults disrupt the flow ofproducts through manufacturingprocesses land cause data loss incomputer centers leading to hours oreven days of lost productivity.Ground faults pose potential healthand safety risks to personnel, creatinghazards such as equipment malfunctions,fire and electric shock.High Resistance-Grounding (HRG) isbecoming more prevalent in industrialand commercial electrical power systemsbecause it eliminates unscheduleddowntime due to ground faults, andimproves personnel safety by preventingground faults from escalating into arcflash incidents. Resistance Groundingis highly recommended for generators,to protect them from damage due toexcessive ground fault currents.10NEMA 3R enclosure containing currentlimiting resistor and ground fault relayAvailable with artificial neutral for use ondelta systemsVisual indication of system normal, activeground fault and pulsing activeAvailable for 480V, 600V and 4160Vdistribution systems
The first step in protection is to limitdamaging fault currents through theTo System NeutralNo. 8 AWG Min.use of a High Resistance Groundingsystem.The next step requires the fault tobe located and repaired before aV0-500VA0-5AGFsecond fault occurs.Ground FaultRelayThe Sleuth pulsing system containsfour key integrated elements that limitdamaging fault currents and provideprocess continuity. Also, the integralpulsing system facilitates the locatingGround FaultActiveGSystem HealthyRGround FaultActiveFPulsing OnTo System GroundNo. 8 AWG Min.of the ground fault in the shortest time,so the operator is able to schedule theisolation and correction of the fault ata convenient time.1. High Resistance Grounding ResistorThis resistor is connected to the wyegenerator supplying the facility. Its functionto non-damaging levels under a singleThis provides the user an opportunity toto detect and clear the fault.point of the transformer oris to limit ground fault currentsline-to-ground fault condition.retain process continuity and2. Hand Held Pulse Tracing SensorThis device, similar to a clamp-on ammeter, allows the user to follow the pulsesfrom their source at the SLEUTH unit through to the specific location of theline to ground fault. Once the fault is located, it can be isolated and repaired.3. Automatic Pulsing SystemOnce the pulsing feature on the SLEUTH system is selected and activated,the system will cyclically limit the fault to 100%, 75% and 50% of theavailable ground fault current. The cyclical pulsing combined with thehand held pulse tracing sensor empowers the user to trace the fault circuitto the point of the fault in even in complex distribution systems withoutde-energizing the load.4. Ground Fault Sensing Transformer and RelayThis microprocessor based digital relay measures ground fault currentusing a 1:1 zero sequence current transformer. It maintains accuracyover a range of 45Hz to 65Hz and filters out harmonics to eliminatenuisance tripping.65287E22237211
GEMINIGEMINI is a unique patented, fail safe, all-in-one neutral groundingsystem that combines ground fault protection with a redundant resistorsystem, in addition to a built-in resistor integrity monitoring relay.Providing protection against any compromising of the resistor integrity,the patented twin resistance paths in combination with the integritymonitoring relay form the heart of the Gemini system. Limiting anyground fault to predetermined and safe levels, the parallel resistancecircuit protects against the damaging effect of a ground fault. Shouldthe integrity of either resistor path be compromised, the secondpath continues to provide the necessary protection while an alarmis activated.Ground faults cause havoc on plantproduction processes, shutting downpower and equipment and critical loads.Ground faults disrupt the flow ofproducts through manufacturingprocesses and cause data loss incomputer centers leading to hoursor even days of lost productivity.Ground faults pose potential health andsafety risks to personnel, creating hazardssuch as equipment malfunctions, fire andelectric shock.High Resistance Grounding (HRG) isbecoming more prevalent in industrialand commercial electrical power systemsbecause it eliminates unscheduleddowntime due to ground faults, andimproves personnel safety by preventingground faults from escalating into arc-flashincidents. Resistance Groundingis highly recommended for generators,to protect them from damage due toexcessive ground fault currents.12Patented fail-safe high resistance groundingsystem with twin resistance pathsOnly monitoring relay capable ofdiscriminating between ground faults, resistorfailure and open and short circuitsEliminates nuisance tripping through adjustabletime delay settings 60 milliseconds upSelf diagnosis through built-in test circuitry
The GEMINI system contains a highresistance grounding unit, a groundfault relay and a resistor integritymonitor. It is available with optionalpulsing capability for easier faultlocation.1. High Resistance Grounding SystemThis resistor is connected to the wye point of the transformer orgenerator supplying the facility. Its function is to limit ground fault currentsto non-damaging levels under a single line-to-ground fault condition.In the case of the GEMINI system there is a parallel resistance circuitcomprised of two identical resistor paths connected from the neutral tothe ground. The parallel resistance circuit is sized to limit any ground faultto predetermined levels. In the unlikely event that one resistor path fails,the second resistor path continues to limit the ground fault to half of thepredetermined levels and still provides full ground fault protection and analarm indicating resistor failure.2. Ground Fault and Resistor Integrity Relay (GFR-RM)In conjunction with a sensing resistor and a series current transformer,the GFR-RM measures current through the neutral grounding resistor,transformer neutral to ground voltage and NGR resistance for continuity. TheGFR-RM compares the measured values against the field settings of relayand provides relay outputs and lighted signal when an abnormal conditionis detected.The GFR-RM is the only relay with the capability to discriminate betweenground faults, resistor failure and open and short circuits. The unit trips in1.5 seconds when NGR failure is detected. NGR failure is determined whenresistance varies to less than 66% or more than 150% of the selected value.3. Automatic Pulsing System (optional)Once the pulsing feature on the GEMINI system is selected and activated, thesystem will cyclically limit the fault to 100%, 75% and 50% of the availableground fault current. The cyclical pulsing combined with the hand held pulsetracing sensor empowers the user to trace the fault circuit to the point of thefault in even in complex distribution systems without de-energizing the load.65287E22237213
sentinelSENTINEL SYSTEMThe Sentinel is the industry’s most advanced high resistancegrounding system. It is designed to protect your continuous process orcritical power system from unnecessary outages of electrical power.The Sentinel detects the event of a single ground fault, signals analarm, and points to the affected branch or feeder. Thus maintenancecan be immediately alerted to the problem and an operator dispatchedto locate the fault to isolate it promptly.Ground faults cause havoc on plantproduction processes, shutting downpower and equipment and critical loads.Ground faults disrupt the flow ofproducts through manufacturingprocesses and cause data loss incomputer centers leading to hoursor even days of lost productivity.Ground faults pose potential healthand safety risks to personnel, creatinghazards such as equipment malfunctions,fire and electric shock.High Resistance-Grounding (HRG) isbecoming more prevalent in industrialand commercial electrical power systemsbecause it eliminates unscheduleddowntime due to ground faults, andimproves personnel safety by preventingground faults from escalating into arcflash incidents. Resistance Groundingis highly recommended for generators,to protect them from damage due toexcessive ground fault currents.NEMA 3R enclosure containing current limitingresistor and ground fault relay and isolation switchPhase and feeder indication resulting in quickerfault locationMonitors and protects up to 50 feeders on one relayAvailable first fault alarm, first fault trip or firstfault time delay tripIntegral resistor monitoring module eliminatesrequirement for separate monitoring relayUnique selective instantaneous feeder trip (sift)on occurrence of second ground fault14
Additional Safety Features12Phase IndicationNGRNGRDSP HRGFeeder IdentificationZSCSDSP HRG.Several Feeders.Motor3ZSCS.Several Feeders.MotorMotorMotorFaulted Feeder OptionsOptions for Faulted Feeder:Alarm Only (No Trip) orTrip with Time DelayTRIPNGRDSP HRGZSCSZSCS.Several Feeders.Motor4MotorSelective Second Ground Fault Protection2nd Ground Fault:Prioritize FeedersTrips least important,maintaining operation onmost importantUp to 50 FeedersTRIPNGRDSP HRGZSCSZSCS.Several Feeders.MotorMotor15
Additional Safety Features5Open/Short ProtectionSystem Ground Monitor:Continually monitors circuitfrom Neutral to GroundTRIPNGRZSCSDSP HRGZSCSAlarms if OPEN circuitAlarms if SHORT circuit.Several Feeders.DSP-DRMComplies with M421MotorMotor6Main-Tie-Main ApplicationsCable adapter CA(S):Controlled by tie breaker contactTRIPTRIPZSCSDSP HRGNGRZSCSZSCS.Several Feeders.MotorAllows coordination of twosystems either separately (Tieopen) or combined (Tie closed)MotorZSCSDSP HRG.Several Feeders.MotorMotorDSP-CADSP-CASTechnical Specifications16Power requirements100-240V, 50/60 Hz or DC, 25 VADielectricRelay contacts to chassis 1500V rms. for 1 minuteControl terminals to chassis 1500V rms. For 1 minute alarm levelIEC-60255-5Trip Level Inhibit25% of systems Ground currentContact RatingsDSP-DFM trip contacts-form C SPDT 10 Amp, 240V AC resistiveDSP-DPS Alarm contacts-form C SPDT 8 AMP, 240 V AC resistiveInsulation voltage withstand / lighting impulse withstand in accordance to IEC-60950PerformanceDSP-DFMPickup accuracy /- 10% of system let-through currentTrip Level Accuracy /- 10ADSP-DSMAlarm Level Accuracy /-10% of IGTemperature rangeOperating temperature 0 C-50 C
MAIN BUSX0display and modular design, the DSPSupply CompartmentOHMNI can be expanded to 50 feedersfor large installations, each with aGdedicated feeder module and sensitivezero - sequence current sensor.MAIN DISCONNECT3PSENTINELNSHUNT TRIP POWERWith its separate easy to read digitalZSCSLOADSPULSE SIGNALOHMNI-PMRESISTORTRIP CONTACTSENSOR INPUTTRIP CONTACTA B CNGSENSOR INPUTDDR2SENSOR INPUTNGR CompartmentLV CompartmentTRIP CONTACT150VARS-485 TONETWORKPOWERAC/DCDSP-DMA B CN eaturesBenefitsDIN-rail partsCompact mounting reduces space requirementsCompact Feeder Modules DSP-DFMLarge systems up to 50 circuits / DSP-OHMNI can be accommodated.Selectable MUTE ON/OFF functionAllows Alarm contact to be used for other applicationsSelectable Trip on 1st fault or Provides user the option of maximizing continuity of service (2nd fault2nd Fault operationTrip) or minimizing fire/damage risk (1st fault Trip). Both can be used onthe same system.0-99min Delay setting on 1st Fault TripAllows time to locate fault and/or orderly shutdown of equipment.10-90% Alarm Level settingUser selected Sensitivity in 10% increments, allows maximum sensitivityto be used while preventing nuisance alarms.Switching Modules DSP-CASProvides co-ordination between systems either vertically (betweenzones) or horizontally (same zone) on multi-zone or main-tie-main systemsNGR monitor DSP-DRM Monitors the status of Grounding Resistor in one DSP-OHMNI compatible unit.Password Protected Setup Four digit codes selectable by user prevent unauthorized setup changes whilestill allowing self-test and read-only data.Self-Test of Modules Internal Self-test of DSP-DFM, DSP-DSM verifies connections to provideassurance of functionality.MODBUS Communications llows the operator to remotely monitor which feeder has faulted as well as theAleakage currents of all feeders for trending purposes.CERTIFIED65287E23271017
FUSIONFUSION is a selective coordinated high resistance grounded systemwith high first fault current.Fusion converts from solid grounding to high resistance groundinggiving an immediate reduction in fault current. This allows the faultto remain on the system without causing further damage and withoutunplanned process interruptions.For faults in minor equipment or smaller feeders it allows theovercurrent device to trip the circuit and clear the fault and maintainssolid grounding.Ground faults cause havoc on plantproduction processes, shutting downpower and equipment and critical loads.Ground faults disrupt the flow ofproducts through manufacturingprocesses and cause data loss incomputer centers leading to hours oreven days of lost productivity.Ground faults pose potential healthand safety risks to personnel, creatinghazards such as equipment malfunctions,fire and electric shock.High Resistance Grounding (HRG) isbecoming more prevalent in industrialand commercial electrical power systemsbecause it eliminates unscheduleddowntime due to ground faults, andimproves p
What does IEEE say about Low Resistance Grounding? IEEE Std 142-1991 Recommended Practice for Grounding of Industrial and Commercial Power Systems Clause 1.4.3 Resistance Grounding The low-resistance method has the advantage of immediate and selective clearing of the grounded circuit, but requires that the minimum ground-fault
Grounding Study and Analysis: Substation Grounding Practices Grounding Concepts - GPR and Touch Potential AEP Innovative Grounding Study Methods Grounding Installation: Traditional Approach and Challenges Grounding Application and Installation Change Management Testing: Grounding Integrity Testing Conclusion and .
buried depth of the grounding grid, the resistance reducing effect is not obvious, in particular to areas with high soil resistivity. Therefore, in general, this method is not adopted in the engineering. The buried depth of the substation grounding grid is about 0.8 m generally. Long vertical grounding electrodes, blasting grounding and deep well
and safe installation of HRG equipment. Index Terms – High Resistance Grounding, Retrofits, Ground Fault Detection, Grounding Transformers, Paper Mills I. INTRODUCTION Power systems engineers have developed several methods of effective grounding of industrial power distributions systems over the years. Historically, the method of system grounding
Grounding Electrode System and Grounding Electrode Conductor Part III zNEC 250.50 (Grounding Electrode System) 250.52 Electrodes Water Pipe if 10 ft. or more of metal water pipe is in contact with the earth. Metal Frame of the Building or Structure where the followin
NEC Table 250.122 - Minimum size equipment grounding conductors for grounding raceway and equipment Table 2 – Minimum size equipment grounding conductors for grounding raceway and equipment Aluminum Cable Tray Systems Table 392.60(A) – Metal area requiremen
Article 250.1 Scope. Article 250 is organized into 10 different parts that deal with specific requirements with regards to bonding and grounding. The specific parts are as follows: (I) General (II) System Grounding (III) Grounding Electrode System and Grounding electrode Conductor (IV) En
grounding bar in the service equipment. The grounding electrode conductor shall extend to a grounding electrode (a ground rod or other effective electrode). 6.2.3 An equipment grounding conductor shall originate at this service equipment and shall be installed with the circuit conductors to the waterer. 6.2.4 The equipment grounding conductor .
English Language Arts & Literacy in History/Social Studies, Science, and Technical Subjects ISBN 978-0-8011-17 40-4 . ISBN 978-0-8011-1740-4. Bar code to be printed here. California Common Core State Standards. English Language Arts & Literacy in . History/Social Studies, Science, and Technical Subjects. Adopted by the. California State Board of Education . August 2010 and modified March 2013 .
