3 Phase Induction Motor current calculator is used to calculate the rated and full load amperes of the motor. Enter the rated volts, amps, power, and efficiency to find the current flowing through the motor.
The 3 phase Induction motor is popular for its efficiency and is widely employed in the electric systems for doing mechanical work. The current flowing through motor depends on various factors including its voltage, power factor, efficiency and rated power. Mathematically, rated load amperes and full load amperes are defined as:
Where
The calculation will be performed for the air-cooled, three-phase motors for continuous duty cycle S1, standard efficiency, 50 or 60 Hz, SF 1.00, lap or concentric, single or double-layer, for the maximum power from the given iron core. Please, carefully review the information needed, and be aware that more details gives more accurate results. The winding calculator allows you to find the optimum winding layout for your electric motor in a fast and convenient way. You can investigate three-phase integer-slot, fractional-slot and concentrated windings, both with single and double winding layers where appropriate. Synchronous speed, frequency, and poles of the induction motor are related by the formula: η sync = (120. f e) / P η sync = Synchronous speed f e = Frequency of the system. Figure 3 Relationships Between Power, Current, Power Factor and Motor Load Example: Input Power Calculation An existing motor is identified as a 40-hp, 1800 rpm unit with an open drip-proof enclosure. The motor is 12-years old and has not been rewound. The electrician makes the following measurements: Measured Values: V ab = 467V I a = 36 amps. If the copper loss is too high, select a winding distribution that is more efficient. In order to calculate the copper loss, you need to know the full-load current. To calculate that, you need all of the design characteristics of the motor including stator and rotor resistance and leakage reactance, magnetizing reactance and iron loss.
HP = Horsepower
kW = kilowatts
E = V = voltage
SF = Service factor
PF = Power factor
kW and HP are used to represent the power. Whereas 1 HP = 745.6 kW
%Efficiency of the motor is defined as its rated efficiency and it is ration between output input.
Service factor is the ratio of actual maximum power to the rated power mentioned on the plate of the motor.
Example # 1: A 230 volt three phase, 1/2 HP induction motor has an efficiency rating of 88% and a power factor of 85%. Find the amp-load of the motor.
Solution: I = (0.5 * 745.7)/(√3 *230 * 0.85 * 0.88) = 1.25
Example # 2: A 2 kW, 3 phase motor at 400 V has an efficiency rating of 85% and the power factor of 80%. Find the amps. Find the FLA when the service factor is 1.25.
Induction Motor Rewinding Calculation
Solution: I = (2,000)/(√3 * 400 * 0.85 * 0.8) = 4.25 A -> RLA
Whereas the For FLA multiply RLA with 1.25.
FLA = 1.25 * 4.25 = 5.31 A
So you just burned your motor or you want to rewind your motor for more power/torque, but are confused as to how to wind the motor. Just enter the no of poles ( the no of stator arms) and the no of magnets in this calculator and it will provide a winding schematic.
The no of poles/stator arms of the motor are always in the multiples of 3 and hence the motor has 3 phases. Each phase is winded separately. If you mark any stator arm as phase one, then the next stator arm of the same phase can be obtained by adding 3 to the first stator arm.
Induction Motor Rewinding Calculations
So stator arms 1, 4,7,10…ect belong to one phase. Similarly stator arms 2,5,8,11…etc belong to phase two and stator arms 3,6,9,12.. belong to phase three.