# Does an automatic power factor controller save units in an Alwar oil mill, as the Alwar manual books it?

Canonical: https://senseible.earth/answers/alwar-oil-mill-apfc-15-kvar-for-45-kw-load

The Bureau of Energy Efficiency (BEE) Alwar manual lifts a 45 kilowatt (kW) load from power factor 0.90 to 0.99 with 15 kilovolt-ampere reactive (kVAr) of capacitors, and books 4% of the bill, converted to units at rupees (Rs) 4.8: 212,500 kilowatt hours (kWh). The 4% looks like a rupee rebate, so those units are most likely not real.

## The sum in the manual

- Load 45 kW, power factor 0.9 now and 0.99 proposed, an automatic power factor controller (APFC) with 15 kVAr, 3,000 hours a year, Rs 4.8 a kWh.
- Saving written as 0.04 x electricity bill a month x 12 months x Rs 4.8 a kWh. The manual notes that some units already keep a good power factor and get a rebate from the state electricity board.
- Capacitors Rs 400 to 600 a kVAr. Cluster cost Rs 9.1 lakh, saving 212,500 kWh and Rs 10.2 lakh, payback 11 months.

## Is 15 kVAr the right size for 45 kW? Yes

Reactive power for 45 kW at power factor 0.90 is 45 x tan(arccos 0.90) = 45 x 0.484 = 21.8 kVAr. At 0.99 it is 45 x 0.142 = 6.4 kVAr. The difference is 15.4 kVAr, so the manual's 15 kVAr is the right size. The manual prints this formula, Required kVAr = Load (kW) x [tan(cos-1 PFi) minus tan(cos-1 PFf)], where PFi and PFf are the initial and final power factor; the 21.8, 6.4 and 15.4 figures are our arithmetic with it.

## What the 4% is made of

- The manual's background says the state electricity board gives a flat rebate of 1.0% of the monthly bill for every 1% of power factor above 0.95. The plan lifts the power factor to 0.99, and 0.99 minus 0.95 is 4 points, so the 4% most likely comes from that rebate (our reading). It is a share of the bill in rupees, not a share of units.
- The manual's formula then multiplies that rupee share by Rs 4.8 a kWh, and 212,500 kWh is Rs 10.2 lakh divided by Rs 4.8 (1,020,000 / 4.8 = 212,500). So the kWh, and the carbon dioxide built on it, are most likely not real units (our reading). The manual's list of benefits does name a rebate on the bill, and a reduction in kWh as well.
- Rs 9.1 lakh at Rs 400 to 600 a kVAr buys 1,517 to 2,275 kVAr, which is about 100 to 150 sets of 15 kVAr.
- Power factor correction mainly changes what the utility bills: a rebate or penalty around a set power factor, or kilovolt-ampere hour charges. A Morbi report on this site counted rupees and zero kWh for the same kind of project. This manual turns the rupee rebate into kWh. Capacitors do trim current, and so cable losses upstream of them, which is a small effect (our note).

## Before you count it

1. Read your tariff order: is there a power factor rebate or penalty, and is the bill in kWh or kilovolt-ampere hours?
2. Read the last 12 months of power factor off the bill.
3. Count the rupee change from the bill. Count kWh only if the meter shows fewer kWh after the capacitors go in.

## The size check and the manual's totals

- Reactive power at 0.90: 45 x 0.484 = 21.8 kVAr. At 0.99: 45 x 0.142 = 6.4 kVAr. Needed: 15.4 kVAr
- Manual: 212,500 kWh x Rs 4.8 = Rs 10.2 lakh. Payback 9.1 / 10.2 x 12 = 10.7 months, printed as 11
- If it were real units: 212,500 x 0.675 = 143,438 kg of carbon dioxide (CO2), about 143 tonnes, at the financial year 2025-26 grid factor. The likely answer is none, since the 4% looks like a rupee rebate
- If your gain is a rebate only: no kWh and no CO2 change

Load, power factor, hours and tariff are the manual's, at its date. Your tariff order sets the real rebate.

## What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the kWh and the amount on each bill sit side by side, which helps tell a rebate from a unit change. It does not read power factor from a meter or size capacitors.

- [Morbi power factor report: bill saved, not units](https://senseible.earth/answers/morbi-power-factor-report-saves-the-bill-not-units)
- [Target power factor by equipment](https://senseible.earth/answers/target-power-factor-by-equipment)
- [Rooftop solar and the power factor on a kVAh bill](https://senseible.earth/answers/rooftop-solar-lowers-power-factor-kvah-bill)
- [Do the Alwar manual totals add up](https://senseible.earth/answers/alwar-oil-mill-manual-totals-checked)
- [Carbon calculators](https://senseible.earth/calculators)

Sources: [Bureau of Energy Efficiency and Confederation of Indian Industry, Manual on energy conservation measures in the Alwar oil mill cluster (SAMEEEKSHA)](https://sameeeksha.org/pdf/dpr/Alwar_Oil%20Mill.pdf), [Central Electricity Authority, CO2 Baseline Database for the Indian Power Sector (grid factor 0.675 kg CO2 per kWh, financial year 2025-26)](https://cea.nic.in/cdm-co2-baseline-view?mappingId=234&lang=en)

Last reviewed 2026-11-06. Figures are the manual's, from the Bureau of Energy Efficiency Small and Medium Enterprises (SME) programme. The manual books a 4% bill share and converts it to units at Rs 4.8, and tariff rules differ by state and date. Check your own tariff order.