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RESISTOR ELEMENTS |
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Are made of unbreakable corrosion proof jointless
elements edge wound, coiled, formed, punched or
tapered from stainless steel, CU-NI, NI-CR,
Fechral or resistance material as per requirement. |
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CONSTRUCTION |
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Resistors grids are mounted on steel rods
insulated by special heat resistant micanite paper
tubes. Grid washers are of natural mica.
Resistor
grid assembly is mounted on angle iron structure
properly supported to absorb vibration and stress
during fault and transit. End connections of
resistors is brought out to terminal box or
through top or side mounted high voltage bushings.
Stand-off/support insulators are ceramic or epoxy
resin cast. |
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ENCLOSURE |
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Resistor grid assembly is housed in an enclosure
made of heavy gauge sheet steel (≥
2mm) totally
enclosed, vermin proof, with screened or louvered
covers (with fine wire mesh) on front and back for
easy servicing. Bottom screening provided for
maximum cooling of
resistors. Corrosion resistant
nameplate, clear warning labels (danger,
high-voltage, earthing etc.) fixed on enclosure.
Suitable earthing studs are provided on 2 sides.
Enclosures are designed for protection degree of
resistors as per:
IEC 529, IS2147 (from IPOO to IP55). |
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Enclosure options: |
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All Aluminium,
Stainless steel body. |
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Canopy to prevent
standing steel body. |
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Eyebolts in all four
corners for easy handling/hosting. |
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Support stands for
elevating above ground. |
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TERMINALS |
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Bushing type terminals for neutral and earthing
connections are housed into a separate vermin
proof, weather proof compartment. Epoxy insulated
terminals are provided for terminating the
specified size of cables, earthing strips and
supplied with tinned copper lugs/strips.
Connections between the equipment neutral and
resistors is done by single core unarmoured cable
of suitable size. Top or Side mounted bushings can
also be provided as per requirements. |
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PAINTING |
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Power coated or epoxy painted as per
specification. Synthetic enamel shade 632 as per
IS-5 |
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OPTIONAL |
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Space heater, C.T'S, P.T'S, Earthfault relays,
Isolators, Contactors, Auxiliary contacts etc. can
be provided as per requirements. |
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TESTING |
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Visual and
dimensional.
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Measurement of
resistor value at room temperature
±
10%.
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1 minute power
frequency High Voltage withstand test: |
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Upto 600 volts
system |
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2Í
PN + 1000
volts. |
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For
M.V.systems |
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2.25
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PN + 2000
volts. |
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Insulation
resistance measurement by Meggar before and after
the power frequency H.V. test.
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Heat run test:
simulated by passing rated current for rated time
on a limited section of resistor in a
proportionate test enclosure to ensure that
complete NGR temperature rise is within specific
range. |
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STANDARDS FOLLOWED |
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IEEE -32-1972,
IS:3043 FOR EARTHING STANDARDS: |
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ALLOWABLE
TEMPERATURE RISE (above 300C) |
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10,30 & 60
SECOND RATING |
- 7600c |
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≥10
MIN RATING |
- 6400c |
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CONTINUOUS
RATING |
- 3850C |
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IS2147 OR IS
12063-FOR DEGREE IF IP PROTECTION: |
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Standard enclosure
is designed to IP23 (to prevent the ingress of
foreign bodies greater than 12mm and rain falling
at any angle upto 600 from vertical)
suitable for indoor or outdoor use. |
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TO
ORDER A NGR, KINDLY SPECIFY |
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SITE CONDITION. |
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SYSTEM DETAILS. |
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LINE TO NEUTRAL
VOLTAGE. |
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INITIAL FAULT
CURRENT. |
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MAXIMUM TIME "ON". |
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RATING : SHORT TIME,
EXTENDED OR CONTINUOUS. |
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ENCLOSURE PROTECTION
DEGREE (IP). |
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ANY OTHER OPTIONAL
REQUIREMENT |
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OVERALL DIMENSIONS. |
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TYPE
TESTED |
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NGR 11 KV, 1 OHM
TESTED O.K. AT VJTI (MUMBAI) FOR:
1 Minute power frequency high voltage withstand
test (28 KV AC RMS 50HZ). Impulse withstand
voltage of 75 KV. |
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