The Alwar manual's motor sum says 10 hours a day and 7,000 hours a year. Which should I use?

The Bureau of Energy Efficiency (BEE) Alwar manual's 50 horse power motor sum prints 10 hours a day and 7,000 hours a year side by side. They do not match: 10 hours on 300 days is 3,000. The 2 kilowatt saving is rupees (Rs) 0.67 lakh at 7,000 hours and Rs 0.29 lakh at 3,000. A lakh is 100,000.

What the sum prints

• A 50 horse power (hp) standard or re-wound motor draws 32 kilowatts (kW). An energy efficient one draws 30 kW. Saving 2 kW a motor.
• The sum then lists "Running 10 hrs/day" and "Hours 7000 hrs/year".
• It ends: 2 kW x 7,000 hours x Rs 4.8 a kilowatt hour (kWh) = Rs 0.67 lakh (a lakh is 100,000) a year a motor. Rs 4.8 x 14,000 kWh is Rs 67,200, so the sum ties to 7,000 hours.

Why the two hours do not agree

• 10 hours a day on 300 days is 3,000 hours. On all 365 days it is 3,650.
• 7,000 hours a year needs about 19.2 hours a day on 365 days, or 23.3 hours on 300 days.
• The manual's other pages show both patterns. It says machines run from 7 to 20 hours a day and whole plants from 6 to 24. The Alwar 50 hp kolhu report uses 10 hours a day and 300 days, which is 3,000 hours.
• The same manual uses 7,000 hours for exhaust fans, where it says the fan "runs continuously", so 7,000 may have been carried over from there. That is our guess, not the manual's.

What it does to the answer

• At 7,000 hours: 14,000 kWh, Rs 0.67 lakh.
• At 3,650 hours: 7,300 kWh, Rs 0.35 lakh.
• At 3,000 hours: 6,000 kWh, Rs 0.29 lakh (28,800 rupees).
• The saving also looks different as a share. 2 kW of 32 kW is 6.25%, a little above the manual's 3 to 4 percentage point and 4 to 5% efficiency gains. Those are efficiency points, not a power share, so the two are not strictly comparable.

Which hours to use for your mill

1. Count the days the mill ran last year and the hours it ran on a normal day. Multiply.
2. Or take a month's kWh from your bill, divide by the motor's measured kW, and see how many hours it can have run.
3. Use the lower of the two answers if they differ, and say which you used.

One 50 hp motor, three hour counts

• Saving: 32 minus 30 = 2 kW
• 7,000 hours: 2 x 7,000 = 14,000 kWh, x Rs 4.8 = Rs 67,200
• 3,650 hours: 2 x 3,650 = 7,300 kWh, x Rs 4.8 = Rs 35,040
• 3,000 hours: 2 x 3,000 = 6,000 kWh, x Rs 4.8 = Rs 28,800
• Carbon dioxide (CO2) at 0.675 kg a kWh, the financial year 2025-26 grid factor: 14,000 x 0.675 = 9,450 kg, 7,300 x 0.675 = 4,928 kg, 6,000 x 0.675 = 4,050 kg

Power draw, tariff and the two hour figures are the manual's. The 300 and 365 days are our arithmetic.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the kWh for each bill you upload is on file by month. The bill shows the whole mill's electricity, not one motor's; for that you need a meter on each line or a few days of readings.

• Alwar efficient motor reports by size
• Motor horsepower to kWh estimate
• Alwar eco ventilators in place of exhaust fans
• Get your first carbon number

Sources: Bureau of Energy Efficiency (BEE), Manual on energy conservation measures in oil mills, Alwar cluster (SAMEEEKSHA), Central Electricity Authority (CEA), CO2 Baseline Database for the Indian Power Sector, version 22.0 (grid factor 0.675 kg CO2 per kWh, FY 2025-26)

Last reviewed 2026-11-07. Figures are from section 3.4.1.3 of the BEE Alwar manual, at its date and tariff. Re-run with your own motor kilowatts, hours and today's tariff.