My pottery unit's motors have been rewound several times: when does the Khurja profile say to replace them, and what does it save?
The Khurja profile recommends replacing a motor that has been rewound more than two times with an energy efficient one, because each rewinding loses about 2% in efficiency. It puts the saving at about 5% of motor energy, which it counts as 107 tonnes of oil equivalent (toe) a year across the cluster.
What a rewind is, in plain words
A motor is a spinning shaft pushed by coils of copper wire. When the coils burn out, a workshop strips them and winds new ones. That is a rewind. A rewound motor works, but each rewind can leave it a little less efficient, which means it turns more of the electricity you pay for into heat instead of work.
What the profile says
- Almost all units in the cluster use locally bought motors, and rewinding more than two times is not very uncommon.
- For every rewinding there is an energy loss of about 2%.
- So it is recommended to replace the motors if rewound more than two times with energy efficient motors.
- The saving it expects is about 5% of the energy used in motors, 107 toe a year for the cluster, in raw material preparation.
What the 2% adds up to
The profile gives 2% for each rewind and does not say how losses add. If each rewind takes 2% of what is left, two rewinds lose 1 less 0.98 x 0.98 = 3.96%, three lose 5.88%, and four lose 7.76%. That compounding is my arithmetic, not the profile's. My comparison: the 5% saving it quotes for a replacement is about the loss after two to three rewinds, though a new efficient motor also gains from its better design, so the two numbers are not the same thing.
What 107 toe means
The profile's own table turns 27.7 million kilowatt hours (kWh) of electricity into 2,385 toe. At that rate 107 toe is about 1.24 million kWh across the cluster, which is 5% of 24.9 million kWh. My arithmetic: for 5% to equal 107 toe, motors must use about 2,140 toe, about 90% of the cluster's electricity, so the profile's figure seems to treat almost all power as motor load.
What to do
- List every motor above a few kilowatts: its kilowatt rating, the work it drives, hours a year and number of rewinds. A paint mark on the casing, dated at each rewind, keeps the count.
- Replace the ones past two rewinds first, starting with those that run longest.
- Take the electricity before and after from your bill, for the same output, so the saving is yours and not the profile's.
One motor, example numbers
- A mill motor drawing an average of 6 kW for 4,800 hours a year: 28,800 kWh
- 5% saving: 1,440 kWh a year
- At the profile's printed energy charge of rupees (Rs) 6.50 a kWh: Rs 9,360 a year
- Carbon dioxide at 0.675 kg for each kWh (financial year 2025-26): 972 kg
- A quote of Rs 25,000 for the new motor (an example) pays back in 25,000 / 9,360 = 2.7 years
Motor load, hours and quote are examples. The 5%, the 2% and the Rs 6.50 are the profile's figures, from 2015, and the tariff has moved since.
What Senseible does here
Senseible reads fuel invoices and electricity bills into monthly records, so a unit's own gas, oil and power lines are on file to set beside the report's figures. It does not measure a kiln or replace an audit.
Sources: TERI, Cluster profile report: Khurja potteries (SAMEEEKSHA), CEA, CO2 Baseline Database for the Indian Power Sector
Last reviewed 2026-11-07. Rewinding rule, 2% loss, 5% saving and 107 toe are from the 2015 profile of The Energy and Resources Institute (TERI) for Khurja. Grid factor from the Central Electricity Authority (CEA). Check your tariff and a current motor quote.