# Electronics and Communication Engineering - Measurements and Instrumentation - Discussion

4.

In 3 phase power measurement by two wattmeter method, the reading of one wattmeter is zero. The power factor of load is

 [A]. 1 [B]. 0.5 [C]. 0 [D]. 0.8

Explanation:

When p.f. = 0.5, 0 = 60° and one of the wattmeters reads zero.

 Kiruthiga said: (Dec 7, 2015) I do not understand. What p.f = 0.5, o = 60.

 Badar Jahangeer said: (Dec 27, 2015) In 3-phase measurement O = 180, 60 degree for each wattmeter, here he told 3-phase measurement with one wattmeter is zero, the remaining two will share, so P.F = 0.5.

 Babu said: (Jan 4, 2016) Power factor = cos \$ = 0.5. So, cos \$ = 1/2, Or, cos \$ = cos 60. So, \$ = 60.

 Subhankar Palit said: (Jan 5, 2016) tan \$ = 1.732 (W1-W2)/(W1+W2). So tan \$ = 1.732 (0.5-0)/(0.5+0). So tan \$ = 1.732. so \$ = 60. cos 60 = 0.5.

 D Aiysha said: (Jan 7, 2016) Phase angle = 60 degree. PF = 0.5. W1 is positive and W2 = 0. One of the watt meter reads zero.

 Mohammad Inam Uddin said: (Aug 27, 2016) When the meter reading is 0 then power factor will not be 0 according to formula base the pf is 0.5 then meter reading is 0 then power factor will be 0.5.

 Krishna said: (Sep 11, 2016) If reading of one wattmetre is = 0, then \$ = 60, therefore cos \$ = 0.5.

 Omendra Singh said: (Jan 9, 2019) In 3 phase supply system phase angle is 120 b/w 3 phase. If one wattmeter is not giving reading then one phase is off. Now phase angle b/w 2 phase is 90 and cos 90 is 0 so how answer is 0.5?

 Kalyan said: (Aug 21, 2019) Please give me the explanation clearly to get the answer.

 Sravan said: (Aug 25, 2020) Can anyone explain me in a simple manner?