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RPM Formula:
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The RPM (Revolutions Per Minute) of motor formula calculates the synchronous speed of an AC induction motor based on the frequency of the power supply and the number of magnetic poles in the motor. This formula provides the theoretical maximum speed at which the motor can operate.
The calculator uses the RPM formula:
Where:
Explanation: The constant 120 comes from converting seconds to minutes (60 seconds × 2 poles per pair) and accounts for the fact that each pair of poles creates one complete AC cycle.
Details: Calculating synchronous RPM is essential for motor selection, speed control applications, and understanding motor performance characteristics in various industrial and commercial applications.
Tips: Enter frequency in Hertz (Hz) and the number of poles in the motor. Common frequencies are 50Hz or 60Hz depending on your region. Pole numbers are typically even numbers (2, 4, 6, 8, etc.).
Q1: What is synchronous speed vs actual speed?
A: Synchronous speed is the theoretical maximum speed, while actual operating speed is slightly lower due to slip in induction motors.
Q2: Why are pole numbers always even?
A: Magnetic poles in AC motors always come in pairs (north and south), so the total number of poles is always even.
Q3: What are common pole configurations?
A: Common configurations include 2-pole (high speed), 4-pole (medium speed), and 6-pole or more (low speed) motors.
Q4: How does frequency affect motor speed?
A: Motor speed is directly proportional to frequency. Higher frequency results in higher RPM, which is the basis for variable frequency drives (VFDs).
Q5: Can this formula be used for DC motors?
A: No, this formula is specific to AC induction motors. DC motor speed is controlled by different principles involving voltage and field current.