In two wattmeter method the phase angle is tanφ = √3(W1 − W2)/(W1 + W2) tanφ = √3(500 − 500)/(500 + 500) tanφ = 0° φ = tan−10° = 0° Power factor = cosφ PF = cos0° = 1
Universal motors may be powered by either AC or DC power sources.
The universal motor is constructed in the same way as a series-wound DC motor. However, it is designed to operate with either AC or DC applied.
The series-wound motor is the only type of DC motor that will operate with AC applied.
The windings of shunt-wound motors have inductance values that are too high to allow the motor to function with AC applied.
The series-wound motors have windings that have low inductances (few turns of large diameter wire), and they, therefore, offer a low impedance to the flow of AC.
The universal motor is one type of AC motor that has concentrated or salient field windings. These field windings are similar to those of all DC motors.
The ratio of luminous flux leaving the surface (Reflected Light) to the luminous flux incident on it (Incident Light) is known as the reflection factor.
Reflection Factor = Reflected light/Incident light
The value of the Reflection factor is always less than 1.
The total number of the conductor in stranded cable is given by
N = 3x2 − 3x + 1
x = no. of layer
For layer 1
N1 = 3(1)2 − 3(1) + 1
N1 = 1
For layer 2
N2 = 3(2)2 − 3(2) + 1
N2 = 7
In layer 2 no. of conductor = N2 − N1 = 7 − 1 = 6
For layer 3
N3 = 3(3)2 − 3(3) + 1
N3 = 19
In layer 3 no. of conductor = N3 − N2 = 19 − 7 = 12
Voltage = 440 V
Frequency = 50 Hz
Slip = 10% =0.1
Rotor frequency = slip × frequency
= 0.1 × 50 = 5 Hz