1. What is 3 Phase Motor RPM?

The RPM (Revolutions Per Minute) of a 3-phase motor is determined by the frequency of the power supply and the number of poles in the motor. It represents the rotational speed of the motor's shaft.

2. How Does the Calculator Work?

The calculator uses the 3-phase motor RPM formula:

Where:

• \( f \) — Frequency of power supply (Hz)
• \( Poles \) — Number of poles in the motor (always an even number)
• 120 — Constant for 3-phase motors

Explanation: The synchronous speed of the motor is directly proportional to the frequency and inversely proportional to the number of poles.

3. Importance of RPM Calculation

Details: Knowing a motor's RPM is crucial for proper equipment selection, speed matching, and ensuring optimal performance in industrial applications.

4. Using the Calculator

Tips: Enter the power supply frequency in Hz and the number of poles in the motor. Common frequencies are 50Hz or 60Hz. Pole numbers are typically 2, 4, 6, etc.

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 120 used in the formula?
A: The 120 comes from (60 seconds × 2) where 60 converts Hz to RPM and 2 accounts for the alternating current cycle in 3-phase systems.

Q2: What is the difference between synchronous and actual RPM?
A: Synchronous RPM is theoretical speed. Actual RPM is slightly less due to slip (typically 2-5% less for induction motors).

Q3: What are common pole configurations?
A: Common configurations are 2-pole (~3600 RPM at 60Hz), 4-pole (~1800 RPM), 6-pole (~1200 RPM), etc.

Q4: Does voltage affect motor RPM?
A: No, RPM is primarily determined by frequency and poles. Voltage affects torque but not synchronous speed.

Q5: How accurate is this calculation?
A: It calculates synchronous speed perfectly. For actual speed, subtract slip percentage (typically 2-5% for induction motors).