Getting motors through the monsoon
Damp windings, flooded pits and idle pumps: what to check before and during the rains in Pune’s plants.
Inside our rewinding shop: a burnt motor’s week
Strip, record, wind, varnish, bake and test: what happens to a 37 kW motor from the day it arrives.
Our rewinding shop takes in about 60 motors a month, from 1 kW pump motors to 250 kW mill drives. Each one follows the same steps. Here is the week of a typical job: a 37 kW, 4-pole motor from a Chakan plastics plant that burnt out on a Monday night.
On Tuesday morning it is opened, photographed and inspected. We check the bearings, shaft and rotor, and test the stator core for hot spots. The winding data is recorded before anything is removed: number of turns, wire size, coil pitch and connection. This record matters more than anything else in the job. The customer gets photos and a quote by Tuesday afternoon.
Once approved, the old winding is cut out and the core is cleaned in a controlled burn-off oven, which loosens the old varnish without damaging the steel laminations. On Wednesday and Thursday two winders, led by Prakash, wind new coils on formers using copper wire of the same gauge, insert them with fresh slot insulation, connect and lace them.
On Friday the stator is dipped in varnish and baked overnight at about 150 °C, which seals the coils and holds them firmly. Saturday is for new bearings, assembly and testing: insulation resistance, winding resistance on each phase, a surge comparison test and a no-load run where we log current and vibration. The readings sheet goes out with the motor, which was back in Chakan by Monday.
