Guide to Motor Run Capacitor Ratings from MFD to Voltage
Objective
In this blog, we want to help dealers, electricians, pump owners and students read a capacitor label correctly, understand what each number means, and pick the right replacement without guessing.
Key Takeaways
MFD, µF and microfarad all mean the same thing.
A full rating has three parts: MFD, voltage rating and tolerance.
Match MFD and voltage from the label or motor nameplate. Do not guess by blade size or horsepower alone.
Never fit a voltage lower than the label shows.
If the label has worn off, share your motor details or a photo with the maker.
Introduction
Your borewell pump is humming, the shaft won’t turn, and the old capacitor’s label has faded. Which one do you buy?
Did you know?
Electric motor systems used 53% of global electricity consumption in 2023, and 87% in agriculture, according to the IEA 4E programme. iea-4eiea-4e
The problem is that many buyers pick a capacitor by horsepower or guesswork. A wrong pick can mean a second visit and an unhappy customer.
The fix is simple. In this guide, we walk you through every motor run capacitor rating, from MFD to voltage, in easy steps. By the end, you can read any label and choose with confidence.
In This Guide
What is a motor run capacitor?
What the label tells you
How to read it in 6 steps
Capacitor microfarad range by application
Voltage: the other half of the rating
A scenario you may recognise
Standards, tolerance and build quality
For dealers: 7 marketing habits that work
Conclusion and FAQs
What Is a Motor Run Capacitor?
Let’s start with a plain definition. A motor run capacitor is a small electrical part that stays in the circuit while a single-phase motor is running. Capacitors help motors and fans start smoothly, run steadily and use less power. You will find them in fans, pumps, air conditioners, washing machines and farm motors.
Don’t mix it up with a start capacitor. A start capacitor helps the motor get going. Submersible pumps often use both. Our submersible start capacitors, for example, range from 40/60 to 250/300 MFD, while the run capacitors go up to 100 MFD.
What the Label Tells You
Most labels carry more than one number. Here is what each one means and what you should do about it.
What you see | What it means | What you should do |
MFD or µF | The capacitance value | Match it to the nameplate or manual |
Voltage (e.g. 440V) | The working voltage the part is built for | Never go lower than this |
Tolerance (e.g. ±5%) | How far the real value may differ from the label | Note it, especially for bulk orders |
Standard (e.g. IS 2993) | The Indian standard it follows | Prefer marked, certified parts |
Body and filling | Aluminium or plastic, oil-filled or dry-filled | Choose to suit the motor’s working place |
How to Read a Capacitor Label in 6 Steps
Let’s break it down. Keep this checklist handy on your phone.
Switch off the supply. Have the capacitor discharged safely before you touch it.
Find the MFD. A label might read “25 MFD” (an example only).
Note the voltage next to it, such as 440V.
Check the tolerance, if printed.
Compare all three with the motor nameplate or user manual.
Match them. If the label has faded, take a clear photo of the old capacitor and the nameplate, then send both to your supplier.
That last step helps more than you think. When we quote, we ask for the product type, MFD, voltage, body type, quantity and city. A photo of the old capacitor makes it easier.
Capacitor Microfarad Range by Application
What this really means is that the capacitor microfarad range follows the job. A small ceiling fan and a big irrigation pump do not need the same value. Here is the range across the capacitors we list on our website.
Application | MFD range | Voltage |
Fan (oil-filled and dry-filled) | 0.5 to 10 | 440V |
Submersible motor run | Up to 100 | See product page |
Submersible motor start | 40/60 to 250/300 | See product page |
Air conditioner (single and dual) | 5 to 80 | See product page |
Washing machine (dual) | 5.33+xx to 12+xx | 440V |
Agriculture (Agri Duty, Agri Gold) | 50 to 216 | 440V |
Lighting | 4 to 42 | 250V |
Notice how agriculture capacitors start at 50 MFD, while fan capacitors stop at 10. Farm pumps run hard, often in dust, heat and uneven power, so they need bigger, tougher parts. Always check our Motor Capacitor page for the exact motor run range before you order.
Voltage: The Other Half of Your Rating
Many people check MFD and forget voltage. A correct motor run capacitor rating always includes both.
Start with your supply. Homes in India use a 230V single-phase supply. Factories use a 415V three-phase supply. Then match the voltage printed on the old capacitor or the nameplate. Many of our fan, washing machine and agricultural capacitors are rated 440V, and our lighting capacitors are 250V.
In that case, here’s the simple rule: never go below the label voltage. If you are thinking of a higher voltage with the same MFD, check with the motor maker or our team first. Match the MFD exactly.
A Scenario You May Recognise
Say a customer walks into your shop with a borewell pump that hums and won’t start. The capacitor label has faded, and the customer says, “It is a 1 HP motor, just give me any capacitor.”
It is tempting. But horsepower alone does not give you the MFD. So you ask for the nameplate, or the manual, or you check the old capacitor. If all three fail, you share the motor details with your supplier.
It takes ten extra minutes. Fitting the wrong motor run capacitor rating can cost you a repeat visit, a lost customer and a bad word at the next tea stall. A dealer who has sold our capacitors for eight years told us that customers rarely come back with complaints. Getting the match right the first time is a big reason why.
Standards, Tolerance and Build Quality
A good rating on paper still needs a well-built part. Concap’s motor run capacitors follow IS 2993, and our Pilerne unit holds the BIS licence for IS 2993 Part 1. Other products follow their own standards:
Product | Standard |
Fan capacitors | IS 1709 |
Motor run, submersible, air conditioner, washing machine | IS 2993 |
Lighting capacitors | IS 1569 |
Power factor correction capacitors | IS 13340 |
Our fan capacitors have a tolerance of ±5%. We use SH-MPP self-healing film, non-PCB jelly oil and eco-friendly resin in aluminium or plastic bodies. Our air conditioner and power capacitors also carry an overpressure disconnector for safety. For the full motor capacitor specifications, open our Motor Capacitor page or download the catalogue from Downloads.
For Dealers: 7 Marketing Habits That Work
If you sell capacitors, a good guide on your own website brings buyers to you. Here are seven habits that help in 2026:
Build a website that converts visitors into customers: Put your phone number, a quote button and a label guide on the first screen.
Invest in local SEO first: Add your city and keep your Google Business Profile updated before you spend more on ads.
Track marketing metrics that matter: Count calls and quote requests, not just page views.
Create content that answers customer questions: Use the FAQs below as a starting point.
Optimise for mobile users: Most buyers search from a phone, so keep pages fast and add a tap-to-call button.
Use email marketing to stay top of mind: Send repeat buyers a short monthly note with stock updates and tips.
Review your marketing performance every week: Fifteen minutes every Monday is enough to see what works.
Read the Label, Save the Motor
Reading a motor run capacitor rating takes two minutes. Check the MFD. Check the voltage. Check the tolerance. Match all three with the nameplate or manual. And if you are not sure, ask before you buy.
Your next step: Try our Calculator, download the catalogue from Downloads, or contact us with your motor details and a photo of the old capacitor. The Concap team will help you pick the right one.
FAQs
1. What does MFD mean on a capacitor?
MFD stands for microfarad, the same as µF. It is the capacitance value printed on the label.
2. How do I know which MFD capacitor my motor needs?
Check the motor nameplate, the user manual or the old capacitor. If none is available, share the motor details with your supplier.
3. Can I use a capacitor with a different MFD?
Match the MFD given on the nameplate or label. A different value can change how the motor performs, so check with the motor maker first.
4. What is the difference between a run capacitor and a start capacitor?
A run capacitor stays in the circuit while the motor runs. A start capacitor helps the motor get going.
5. What voltage should a motor run capacitor have?
Use the voltage on the label or nameplate, and never go lower. Many of our fan and agriculture capacitors are rated 440V.
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