To calculate RPM for an AC induction motor, you multiply the frequency in Hertz (Hz) by 60 — for the number of seconds in a minute — by two for the negative and positive pulses in a cycle. You then divide by the number of poles the motor has: (Hz x 60 x 2) / number of poles = no-load RPM.
What is 120 in motor speed formula?
The equation for calculating synchronous speed is: S = 120 f/P speed = constant (120) times frequency of power source (60 Hz) divided by number of poles used in the motor (P).
What is the formula of motor?
Electric Motor Formula
|TO FIND||DIRECT CURRENT||SINGLE PHASE|
|HORSE POWER||V x I x EFF 746||V x I x EFF x PF 746|
|CURRENT||P V x EFF||P V x EFF x PF|
|EFFICIENCY||746 x HP V x I||746 x HP V x I x PF|
|POWER FACTOR||——||Input Watts V x I|
What is the speed of a motor?
Definition. Speed of a motor is the magnitude of the rotational velocity of the motor shaft. In a motion application, speed of the motor dictates how fast the axis rotates – the number of complete revolutions per unit time.
What is synchronous speed and it’s formula?
The synchronous speed of an AC motor is determined by the frequency of the source and the number of poles. The RPM is calculated by multiplying the frequency times 60 and dividing by the number of pairs of poles. Some motors are designed to operate at synchronous speed. …
What is slip formula?
If the revolving magnetic flux’s synchronous speed & the speed of rotor are Ns & Nr in the motor, then the speed among them can be equivalent to (Ns – Nr). So, slip can be determined as. S = (Ns – Nr) / Ns.
How is BHP calculated?
Calculating Brake horsepower
- BHP = (Torque × RPM )/5252,where torque is lb -ft and n = revolution per min.
- BHP = BP /33000,where BP (in watt ) = Torque×2π×RPM (RPM in min. ) Where torque in the formula of BP is in lb -ft.
- BHP =BP (in Watt ) / 746 we get it in horse power ,since 1 HP = 746 watt.
What is the formula for work done?
To express this concept mathematically, the work W is equal to the force f times the distance d, or W = fd. If the force is being exerted at an angle θ to the displacement, the work done is W = fd cos θ.
How do you determine if a motor is AC or DC?
Look for the stator core construction and rotor. If there is no commutator, then it is a AC motor. If there is a commutator and brushes, it may be either a DC motor or an AC commutator motor (Universal motor).
Is torque a speed?
Torque is the rotational equivalence of linear force. Speed measures the distance covered in unit time. The relation between torque and speed are inversely proportional to each other. The torque of a rotating object can be mathematically written as the ratio of power and angular velocity.
How do you slow down an AC motor?
YES, you can easily slow down or reduce the rated speed by applying variable voltage or frequency. For slip-ring induction motors this process is very easy and it can be done by inserting a series resistance in rotor circuit (it will vary the motor torque also).