At which angle in two wattmeter method, one wattmeter show zero readings -
At which angle in two wattmeter method, one wattmeter show zero readings - Correct Answer Φ = 60°
Concept:
The diagram of 3 phase 2 wattmeter is given below.
(Phase angle)
Wattmeter readings (W)
Remarks
W1
W2
1.
Pf = unity
(ϕ = 0° )
+ve
+ve
W1 = W2
2.
0.5 < p.f.< 1.0
(60° > ϕ > o° )
+ve
+ve
W1 > W2
3.
Pf = 0.5
(ϕ = 60° )
+ve
zero
Total power = W1
4.
0 < Pf < 0.5
(90° > ϕ > 60° )
+ve
-ve
|W1|> |W2| (Total power is positive)
5.
Pf = 0
(ϕ =90° )
+ve
-ve
|W1|= |W2| (Total power = zero)
From the above table, it is clear that when the phase angle is 60°(Φ = 60°) then one wattmeter shows zero reading.
মোঃ আরিফুল ইসলাম
Feb 20, 2025