TETV HV Induction Motors

FEATURES

• Fabricated Robust Steel construction for frames.
• Uniform internal cooling circuit.
• Axial Cooling for smaller ratings, both radial and axial ventilation for larger ratings.
• Basic mounting dimensions as per IS.
• Class ‘F’ insulation system, both Resin rich & Resin poor (VPI) varieties available.
• Rotors are dynamically balanced.
• Rotor bars are brazed with end rings by One Shot Brazing process.
• Environmentally friendly motors to meet all Drives
• Fault tested Phase Segregated Terminal box.
• RTD, BTD, Dial type Temperature indicator available.
• Separate Terminal Box available for Neutral point, RTD, BTD termination purpose.
• Provision for Magnetic Slot Wedge to improve Efficiency, Power Factor and improve Electromagnetic noise
• Provision for special Epoxy paint system
• The motors are suitable to service both indoor and outdoor, and is strongly recommended for dusty environments.

CONSTRUCTION

Standards and regulations

• The machines comply with IS-325, relevant BS and IEC. The motors are offered to specific requirements of the customers.
• The motors are designed for voltage and frequency as per IS 325. The standard values and the permissible variations are :
• Voltage – 2.2 to 11 kV ± 10%
• Frequency – upto 60 Hz ± 5%
• Motors are also available to suit systems where voltage and frequency variations exceed the standard limits.
• The rated outputs correspond to the continuous running duty with cooling air temperature of 40°C and site altitudes not exceeding 1000 m. above m.s.l.

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Types of construction

The machines are available in types of construction B3, V1 or B35.

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Ventilation system

The machines have closed circuit with a concentric tube nest Cooler, which is Integral with the frame. Rotor is fitted with shaft-mounted external and internal fans.

For 2-Pole machines the internal and external fans are uni-directional. The external fan is located in the fan casing on the non-drive-end and forces the open-circuit air through the cooling tubes of the stator frame.

The internal fan in the main compartment forces the primary air to circulate in symmetrical ducts in the laminated rotor core. The primary air circulates through the end Windings and the ducts in the core packs and extracts the heat to the cooling tubes.

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Degrees of protection

The machines are manufactured with a degree of protection IP 54 or IP 55, corresponding to IS 4691 or IEC 34-5. Method of cooling complies with IC 0151.

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Stator frame

The stator frame is of welded construction. The axial cooling tubes are expanded into the two end walls.

The stator core pack is fitted centrally in the stator frame and secured against rotation and displacement.

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Winding

The stator winding (two layer lap type) constitute of diamond shaped coils and are provided with Mica based insulation system complying with class F insulation requirements.

The insulation system comprises of two varieties – Resin Rich Varnish Impregnated type or, Resin Poor Epoxy Impregnated (VPI) type. The insulation possesses high die-electric strength, high resistance to moisture and aggressive gases and vapours, thus providing excellent mechanical stability and longer life.

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Rotor construction

The rotor consists of a rigid shaft made out of ultrasonically tested steel forging. It is manufactured from carbon manganese steel of grade C45, 150M19, or equivalent. Standard motors have a single plain parallel shaft extension with a single key way and the motors are balanced with a half key fitted. The extension is drilled and tapped as per standard.

All squirrel cage motors have copper or copper alloy rotor cages. Tight fitting rotor bars are butt brazed to copper endrings by one shot brazing process. Rotors of slipring motors are designed and manufactured with high quality Class F/H insulated bars to suit arduous site conditions.

All rotors are dynamically balanced to more stringent levels to make the overall motor vibration severity well below the limits specified in IS I2075.

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End shields

The end shields at the drive and non drive-ends are made of fabricated steel or cast iron. The end shields are designed for fitting the bearing assembly and take care for transmitting the static and dynamic load.

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Bearings

Depending on the design and the operating conditions specified in the order, the machines are fitted with grease lubricated rolling element bearings oil lubricated sleeve bearings, Insulated bearings/brackets are provided on request.

The bearings are selected for minimum maintenance and avoid the need of external lubrication systems.

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Terminal boxes

The electrical connections of the stator winding are terminated in the main terminal box. The terminal box is generally of phase segregated and of double walled construction. The design minimizes the possibility of phase to phase to earth fault, limits its extent and reduces the possible hazard to the personnel in operation.

These Phase Segregated Terminal Boxes (PSTB) have been successfully fault tested at CPRI laboratory, Bhopal, PVC/XLPE cables can be directly terminated to PSTB. Machines containing auxiliary circuits for functions such as anti-condensation heating, temperature monitoring etc. are fitted with separate auxiliary terminal boxes. All types of Terminal boxes comply with degree of protection IP 54/55 or, IEC 34.5.

The number, location and type of terminal boxes can be seen from the dimension drawing of the machine; circuit arrangement and connections of the main and auxiliary circuits are either documented in the O&M manuals or supplied separately.

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Paint System

Surface is primed after degreasing and cleaning using Epilux 610 primer to a dry film. A single finish coat of two pack Epoxy paint is then applied.

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Accessories

Provided on request are PT 100 winding temperature detectors, PT100 bearing temperature detectors, Dial type temperature indicator for bearings vibration monitoring probes shock pulse transducers etc.

Space heaters are provided as standard feature.