NATIONAL ALUMINIUM COMPANY LIMITED - Rites

Degree of protection for motor and bearings shall be IP IP-55 55 for indoor use aand
IP-55 with
removable rain canopy for outdoor use.
Vibration monitor with contacts shall be provided at the DE end of motor bearing for motors
of ratings 1000 kW and above. On line vibration measurements shall be provided for larger
and critical motors.
All motors shall be provided with Bearing (DE & NDE) temperature detectors and 6 nos. stator
winding temperature detectors, RTDs for monitoring alarm and trip conditions. Temperature
shall be displayed on VDU's. RTD's shall be of PT100 type and suitable for digital scanner or
PLC input requirement.
Digital igital type bearing temperature indicator for all motors shall be provided for local
measurement with adjustable alarm contacts.
Each terminal box shall have fault withstand capacity equal to at least rated short circuit level
of the system voltage for 00.25
.25 sec and shall have pressure relief device. Terminal boxes shall
be suitable for termination of FRLS, XLPE cables with cable end seals. Separate terminal boxes
shall be provided for space heaters, RTDs for winding/ bearings temperatures, vibration
monitors etc.
All terminal boxes shall be provided with two earthing studs for termination of protective
earth conductor. Box covers shall be provided with handle to facilitate easy removal.
Low kW range machines may be of TEFC (IC0141) design. For higher rrating,
ating, type of cooling
shall be CACA (IC0151). General accessories like flow switches, space heater, terminal boxes,
drain plug, dowel pipe cable lugs, glands clamp etc. shall be provided.
Vibration intensity shall be limited to values as stipulated in tthe
he IS. Motor shall be designed to
withstand the vibration produced by the driven equipment. Continuous noise level should not
exceed 75 dBA at a distance of 1.0 m from the motor body.
Electrical design shall be same as in case of low voltage induction mot motors ors except the following:
All motors shall have class F insulation but with total permissible temperature limited to 1300C
(as measured by resistance method). Starting current of the drives shall be limited to six times
of full load current.
Motors of rating 1000 kW and above shall be provided with differential protection. Matching
CT and cabling up to switchgear shall be provided by the Bidder.
Motors shall be capable of withstanding locked rotor current at 110 % rated voltage for at
least 2.5 sec (for or motors having staring time up to 20 sec) or 5 sec (for motors having staring
time more than 20 sec) longer up to than starting time under rated load condition at 80 %
voltage. If above condition is not possible then, centrifugal type speed switch to be provided
Technical Specification:Sec-6, Electrical
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