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Disadvantages of Resin Rich coils :

1)The thickness of slot insulation required is more resulting in a bigger slot size and so increases the machine size. 2)The air gap between coil to slot reduces heat dissipation due to high thermal resistance of air resulting in increased - I2Rlosses reducing the machine efficiency. 3)The slide fit coils vibrate twice the line frequency due to electro-magnetic forces rubbing with the slot inner surface. In due course of time, the wall insulations get damaged leading to failure of machine.

Disadvantages of rewinding a machine from VPI technology to Resin Rich technology :

1)The wall thickness in case of VPI technology is comparatively less that required for Resin Rich technology as detailed below :

It is evident from the above table that by rewinding a VPI insulated machine with Resin Rich insulation system, the size of copper has to be reduced suitably to accommodate thicker wall insulation of the coils. Further in Resin Rich system, the coils are inserted in the slots by slide fit which further reduces the copper size to achieve the sliding gap. The total reduction in size of copper leads to approximately 20% reduction in rating of the machine.

2) The presence of air gap between slot to coils reduces heat dissipation from the coils increasing the I2R losses which in turn increases the temperature by 10 to 15 degrees more than initial operating temperature reducing machine efficiency and also leading to faster insulation deterioration and early failure of machine.

3)Increases the possibility of slot insulation damages by rubbing of coils in slot during operation.

4) Increase in overhang length to ease feeding of coils into the slots increases the length and resistance of coil which in turn increases the I2R loss and reduces the efficiency of the machine.

Difference between VPI and resin rich system

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Work shop facilities

Overhead Crane facilities upOverhead Crane facilities up--to 75 tons.to 75 tons.

VIP Plant 5 Meter Dia 12 meter hightVIP Plant 5 Meter Dia 12 meter hight

Elctrical oven 12 ftsX 12 Fts Elctrical oven 12 ftsX 12 Fts

Mobile crans upto 5 tons Mobile crans upto 5 tons

Dynamic balancing machine UpDynamic balancing machine Up--to 3000 rpm weight 30 tonsto 3000 rpm weight 30 tons

TestTest--bed for no load trail 6.6 KV 6 MW motorbed for no load trail 6.6 KV 6 MW motor

Lamination varnishing plantLamination varnishing plant

HT coil manufacturing plantHT coil manufacturing plant

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70 ton balancing machine

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Handling Facility

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