# Is a VFD on a yarn doubling machine worth it for a small textile unit?

Canonical: https://senseible.earth/answers/doubling-machine-vfd-textile-saving

Usually yes, if you size the saving on your own meter. BEE's Solapur report puts a drive at Rs 0.31 lakh and the saving at 12%, from a trial on one cluster machine: 5,640 kWh and Rs 0.14 lakh a year, payback 2.21 years at Rs 2.50 a kWh. A higher tariff shortens it in step.

## Why the motor wastes power

A doubling machine twists two single yarns into one stronger yarn. Its motor runs at one speed all through the doff, although the spindles need less speed while the bobbin is small and full speed only near the end. A drive runs the motor slow early and fast late. Solapur has about 500 doubling machines, most of them old.

## What the report counts

- Saving: 12%, from a demonstration on one doubling machine in a cluster unit.
- Machine: 400 spindles, 7.5 HP motor, about 300 kg of yarn a day, 12 hours a day for 300 days.
- Cost: drive, panel and cabling Rs 0.23 lakh, fitting Rs 0.07 lakh, interest Rs 0.01 lakh, Rs 0.31 lakh in total.
- Saving: 12% of 47,000 kWh = 5,640 kWh, Rs 0.14 lakh at Rs 2.50 a kWh. Payback 0.31 / 0.14 = 2.21 years.

## The report's baseline does not add up

- Its annexure uses 36,300 kWh and a 4,500 kWh saving, worth Rs 0.11 lakh, which gives a 2.8 year payback.
- Either figure means more than 10 kW for 3,600 hours, from a 7.5 HP (5.6 kW) motor.
- BEE's own readings in three units were 5.1 to 6.8 kWh an hour per machine, which is about 18,000 to 24,500 kWh a year on the same hours.
- So log your machine's kWh for a week first. Saving = 12% of that yearly figure.

## How to decide

1. Fit a clamp-on or panel energy meter on one machine for a week and note kg of yarn doubled.
2. Yearly kWh x 12% = kWh saved. Multiply by the energy charge on your bill.
3. Payback = drive quote / yearly saving. At twice the report's tariff, its 5,640 kWh would pay back in about 1.1 years.
4. Check the shed: drives need a clean, cool spot away from fluff.

## One machine on BEE's own meter readings (estimate)

- 6.0 kWh an hour x 3,600 h = 21,600 kWh a year
- Saved at 12%: 2,592 kWh
- CO2: 2,592 x 0.675 = 1.7 t a year
- On the report's 5,640 kWh: 3.8 t, which matches the report

CO2 at CEA's FY 2025-26 grid factor of 0.675 kg per kWh. The 6.0 kWh an hour is the middle of BEE's three unit readings.

## What Senseible does here

Senseible's calculators turn kWh into CO2 on the current grid factor, and it reads monthly electricity bills into records so the unit's power before and after the drives is on file.

- [Carbon calculators](https://senseible.earth/calculators)
- [Yarn doubling and twisting power per kg](https://senseible.earth/answers/yarn-doubling-twisting-electricity-per-kg)
- [VFD on boiler FD and ID fans](https://senseible.earth/answers/boiler-fd-id-fan-vfd-saving)
- [Solapur textile unit boiler CO2](https://senseible.earth/answers/solapur-textile-unit-steam-boiler-co2)

Sources: [BEE, Detailed project report: variable frequency drive for doubling machine, Solapur textile cluster (SAMEEEKSHA)](https://sameeeksha.org/pdf/dpr/VFD_doubling.pdf), [CEA CO2 Baseline Database, version 22.0](https://cea.nic.in/cdm-co2-baseline-view?mappingId=234&lang=en)

Last reviewed 2026-11-01. Report figures are from a BEE SME programme project report; costs and paybacks are at the report year's prices. Check today's tariff and a current drive quote.