We are renowned manufacturer, supplier and exporter of Neutral Grounding Resistors. These resistors are manufactured in strict compliance with international quality standards by a team of expert professionals having deep and through knowledge of the subject. Offered resistors are mainly use for generators and transformers and are made using steel cast iron, FeCrAl and nichrome. The temperature rise of these resistors is normally 375oC/760oC which can be changed asper the needs of customers. Neutral Grounding Resistors are applicable to AC distribution network for preventing any fault which would occur due to fault in earth wire.
- Termination kit
- Having Safety Screen for enclosures
- Supporting Pedestal structures system
- Have Cable gland & stand off insulators
- Having Earth fault leakage Relay facility
- Resistors having high potential transformers
- Resistors having excellent stainless steel hardware
- Having aluminum enclosure and hot dip galvanized enclosures
- Suitable for both neutral grounding transformer / excitation transformer
Internal Features Of Resistor Enclosures
- Group of Resistance elements are mounted together to form a Bank. Banks are then connected in series or parallel to provide the current and ohmic value required.
- All Resistance Bank to Bank interconnections will be done by solid stainless steel / copper.
- Insulation between resistance element and supporting tie rod is provided by a mica tube.
- In case of continuous current ratings for better heat dissipation, perforated sheet / jali with welded GI wire mesh is provided at the bottom.
- Foundation channels welded or bolted to the angle iron structure are provided on two sides with arrangement to fix on foundation by bolts at site.
- Terminals are brought through Porcelain bushings of appropriate voltage class or brought down as per requirement of customer.
- In case of higher voltage, the banks are placed on stand off insulators housed inside the enclosures, or the enclosures is also insulated from ground by using stand off insulator if asked by customer
- The enclosures designed to give degree of protection required as per custome's requirement for outdoor application DOP-IP-33.
- Canopy is sloped to prevent accumulation of water. Overhang is provided to cover terminal box.
- Forged Eye bolts on Lifting Angles ensure easy handling.
- Removable bolted side covers of suitable thickness mild steel (M.S) are louvered for ventilation.
- The enclosures are painted with synthetic enamel paint of specified shade. Other option are epoxy paint or Aluminum paint. Oven drying or stoving is done on request.
(A) Routine Tests:
- Visual and Dimensional
- Resistance value measurement with 10 % tolerance
- Insulation resistance value measurement by using 500V / 1000V megger before and after dielectric test
- H.V. Test of twice the rated voltage +1000 volts for voltage class below 660 volts or 2.25 times of rated voltage +2000 volts for voltages above 1100 volts.
(B) Type Tests :
Temperature rise test i.e., Heat run test if required will be conducted by passing equivalent / rated current for rated / equivalent time keeping IT Constant through a part of Resistor.
- Having non anti frost heating facility
- Neutral Grounding resistance value is precise
- Neutral Grounding Resistor are easier to install
- Grounding Resistors require virtually no maintenance
- Grounding Resistors valve remain constant throughout lifetime
- Grounding Resistors temperature have shorter time constant facility
- Such Grounding Resistors have longer life and having nor anti condensation heaters
- Neutral Grounding Resistor require constant maintenance due to evaporation of gel and electrolyte the liquid resistors
- Having various types of Enclosure facility
- Can be install both in Indoor or outdoor locations
- Duty rating 10 sec., 30 sec., 60 sec., & continuous etc
- Having both system voltage and operating voltage system
- Grounding Resistor temperature can rise over ambient temperature
- Also having material for enclosure (protection class as per IS-12063)
- Accessories Require such as space heater, current transformer, isolating switch on load & off load, manually or motorised
- Rated Voltage : For neutral grounding / earthing resistor rated voltage means line- to neutral voltage i.e. System Voltage divided by root3 i.e. 1.732.
- Rated Current : Means Initial current that will flow through resistor when it is cold. Normally Full load current value is same as Rated current.
- Time Rating : It is length of time for which NGR must tolerate rated voltage.
- Short Time Rating : Normally it is 10 sec. or 30 sec. or 60 sec. depending on design parameters of protection system. IS-3043 recommends 30 sec. rating.
- Continuous Rating : It is normally 10 % of full load current for healthy system neutral grounding resistor to be designed for continuous rating of 5 % to 10 % of full load current (if required).
- Material of Resistance Element : We offer resistor elements made from any stainless steel or FeCrAl or Cu-Ni or Ni-Cr or any other resistance material as per requirement. Normally formed stainless steel element are best and economical for NGRS.
- Temperature Rise Allowed: Normally Temperature rise is restricted to 375 deg.c. above ambient temperature as per BS-587. It can be 760 deg.c. as per IEEE-32. It can be offered of any other temperature rise as per customer's requirement.
- Construction: NGR include resistor assembly, plus required insulators, internal connections and hardware etc.
- Cabling / Termination : Suitable arrangement and clearance is provided for termination of cable, flats or bus duct as per requirement with undrilled removable gland plate.