In today’s competitive world the electrical insulation materials and the processes are viewed with tremendous QUALITY and COST consciousness as the performance and life of the electrical machines are affected by the quality of the varnishing. The varnishing quality mainly depends on following:
• Insulating & mechanical properties of varnish.
• Proper filling of gaps & voids.
To achieve & ensure the above two points during varnishing one should use the appropriate varnish & method depending on the geometry of the job. In the modern world the mainly resin impregnation method is used because of better mechanical & insulation strength of resin. Normally the resin & hardener mixture is used.
Normally Impregnation is done in following manner :
• Metered quantity of varnish is trickled on preheated rotating job.
• Preheated rotating job is dipped in varnish.
• By vacuum / pressure impregnation method.
Considering the geometry & quantity of the jobs required we have developed following types of varnishing machines. All machines are automatic with manual loading & unloading.
Batch Type Trickle Impregnating MachinesWith heating by passing DC current through electrical winding and varnishing with trickle or dip n roll method.
Trickle Varnish Impregnating Machine is suitable for pre-heating, trickling and post heating of stators. The machine is simple and compact in design. It is easy for operation and maintenance. It is ideally suitable for batch type production of stators. The machine is suitable for carrying out following automatic cycle
Index Type Trickle Impregnating MachinesHeating with Ceramic radiation heaters or hot air circulation and varnishing by trickle and/or dip n roll method.
Trickle Impregnating Machines are suitable for automatic impregnating of stators and rotors by trickle process. Stators and Rotors are heated to pre-determined temperature and then trickled with varnish (Resin + Hardener) and cured until it hardens. They are then ready for unloading manually. They are rotated by chain drive which rotates the spindles mounted on rotating / indexing table at an appropriate speed suitable for trickling. Indexing Table is rotated by motor with gear box and limit or proximity switches.
Vacuum Impregnation Plants / Pressure Impregnation PlantsVacuum Impregnation Plants and Pressure Impregnation Plants is designed for varnish impregnation to be carried out in following steps and will be generally as per the schematic diagram attached.
• Pre-heating the jobs in either Impregnation Chamber or in Oven if you have a less time available.
Evacuation of Impregnation Chamber (after putting the jobs) to make the voids in the jobs clear and drying of jobs for specific time & required temperature / vacuum.
• Induction of impregnant (Varnish) in the Impregnation Chamber from impregnant Tank to submerge the jobs in it.
• Pressurize the Impregnation Chamber with dry air or nitrogen to fill the voids with Impregnant.
• Return the varnish to Impregnant Tank.
• Cure the jobs either in Impregnation Chamber or in Oven for specific time if time available is less.