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Let there be Φ = Useful flux/pole in Wb Z = Number of conductor per phase f = Frequency of induced e.m.f. in c/s P = Number of poles N = Speed in r.p.m. As we know that e.m.f. induced is directly proportional to the rate of change of flux, so the flux cut in … Read more
The power in three phase, which is equal to √3VLILcos Φ.
It can be measured by these following methods:
In ac circuits the power factor has its own significance. There is a lowest limit beyond which it cannot be permitted. In big industries and organisations, special arrangements are made to indicate and limit the lowest power factor for example the power factor demand indicators etc.
Two Wattmeter Method of power measurement can be used for both the balanced or unbalanced loads of 3 Φ 4 wires or 3 Φ 3 wire systems. In this method two wattmeters are connected as shown in Fig. 1. The current coils are connected in series with the load and the pressure coils are connected across the line voltage. The total power consumed by the load is the algebraic sum of both wattmeters reading keeping in view the value of power factor of the load i.e.
p = W1 + W2
In this method, the current coil of the two wattmeters are connected in any of the two lines and the potential coil of both wattmeters are connected with the left third line, in which no wattmeter is connected.