Where:
- HP = Motor power in horsepower
- V = Supply voltage in volts
- f = Frequency in Hz
- PF = Power factor
- k = Constant (typically 50-70 for single phase motors)
Starting capacitor is typically 3-4 times the running capacitor value.
1. Enter the motor power in HP
2. Verify or adjust the default values for voltage, frequency, efficiency and power factor
3. The results will automatically calculate and display
4. Choose a capacitor with equal or slightly higher μF rating than calculated
- Always choose capacitors with a voltage rating at least 1.5× the motor's rated voltage
- For start capacitors, use non-polarized electrolytic type rated for motor starting applications
- For run capacitors, use metallized polypropylene film type rated for continuous duty
This calculator helps determine the appropriate capacitor values for single phase motor applications, including both running and starting capacitors.
The calculations are based on standard electrical engineering formulas and provide a good starting point for selecting capacitors.
These calculations provide estimates only and should be verified with the motor manufacturer's specifications when available.
Always consult with a qualified electrician before making changes to electrical systems.
A capacitor is an essential component for single-phase motors. It helps in starting the motor and also improves its efficiency during operation. This Single Phase Motor Capacitor Calculator allows you to easily estimate the ideal capacitor size for your motor based on its power and voltage.
Why Capacitor Size Matters
Choosing the right capacitor size is important. If it's too small, the motor may not start properly. If it's too large, it may damage the motor or reduce efficiency. This calculator helps you find a balance for safe and efficient operation.
Capacitor Calculation Formula
The general formula used to estimate the capacitor size in microfarads (µF) is:
Capacitor (µF) = (Motor Power in HP × 746) / (Voltage² × 6.28 × Frequency × Efficiency)
Quick Rule of Thumb
For most applications, a simplified rule is:
Capacitor (µF) = 50 × Motor HP (for 230V motors)
Motor Power = 1 HP
Voltage = 230V
Using the quick rule: 50 × 1 = 50µF
So, you can use a 50 microfarad capacitor.
Types of Capacitors Used
- Start Capacitor: High µF, used for starting torque
- Run Capacitor: Lower µF, helps with continuous operation
Where This Calculator Helps
- Home appliances like air conditioners and washing machines
- Water pumps and compressors
- HVAC motors and fans
- General industrial motor setups
Conclusion
The Single Phase Motor Capacitor Calculator helps you avoid guesswork when choosing a capacitor. A properly sized capacitor improves motor start-up and performance while preventing potential damage. Use this tool to increase the life and efficiency of your motor setup.