1. What is 3 Phase Motor RPM Calculation?

The 3 Phase Motor RPM Calculation determines the rotational speed of an AC induction motor based on the power supply frequency and the number of magnetic poles in the motor. This is essential for motor selection and application.

2. How Does the Calculator Work?

The calculator uses the synchronous speed formula:

Where:

• \( Frequency \) — Power supply frequency in Hertz (Hz)
• \( Number\ of\ Poles \) — Total magnetic poles in the motor (always an even number)
• 120 — Constant representing conversion from Hz to RPM

Explanation: The formula calculates the synchronous speed of the motor's magnetic field. Actual motor speed will be slightly less due to slip.

3. Importance of RPM Calculation

Details: Knowing a motor's speed is crucial for proper equipment selection, power transmission design, and ensuring compatibility with driven equipment.

4. Using the Calculator

Tips: Enter frequency in Hz (typically 50 or 60 Hz) and number of poles (common values: 2, 4, 6, 8). Number of poles must be an even number.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between synchronous and actual RPM?
A: Synchronous speed is theoretical. Actual speed is 2-5% less due to slip in induction motors.

Q2: Why must pole number be even?
A: AC motors require pairs of north and south poles, so pole count is always even.

Q3: What are common motor speeds?
A: For 60Hz: 3600 RPM (2-pole), 1800 RPM (4-pole), 1200 RPM (6-pole). For 50Hz: 3000, 1500, 1000 RPM respectively.

Q4: Can this be used for single-phase motors?
A: The formula works for single-phase motors too, but single-phase motors typically have different starting mechanisms.

Q5: How does voltage affect motor speed?
A: Voltage doesn't directly affect synchronous speed, but insufficient voltage may increase slip and reduce actual speed.