basic concept of 3-phase power measurement.

1. FET GKV
MEASUREMENT OF 3- PHASE POWER BY USING WATTMETERS
SUBMITTED TO SUBMITTED BY
YOGESH KUMAR SAIYAM AGRAWAL
LECTURER OF EEE-353 ELECTRICAL ENGG.

2. CONTENT
 Introduction of phase
 Advantage of 3-phase power over 1-phase
 Measurement of electrical power in 3-phase circuit
 3-Wattmeter method
 2-Wattmeter method
 1-Wattmeter method
 Power factor effect on 2-Wattmeter method
 Error due to wattmeter connection

3. INTRODUCTION OF PHASE
PHASE ANGLE = 360 / number of poles .
= 360 / 3
= 120º

4. ADVANTAGE OF 3-PHASE POWER OVER 1-PHASE
POWER
3-PHASE POWER
 Output is greater than 1-phase.
 3-phase motor are self start.
 Torque of 3-phase motor is uniform.
 Power factor of 3-phase machine is
higher.
 Efficiency is higher than 1-phase
machine.
 More reliable and capable than 1-
phase machine.
 Required less amount of copper, For
the same output.
1-PHASE POWER
 Output is less than 3-phase.
 1-phase motor are not self start.
 Torque of 1-phase motor is pulsating.
 Power factor is lower than 3-phase machine.
 Efficiency is lower than 3-phase machine.
 Less reliable and capable than 3-phase
machine.
 Required greater amount of copper, For the
same output.

5. MEASUREMENT METHOD FOR ELECTRICAL POWER IN 3-
PHASE CIRCUIT
Following 4 methods are given below :
1) 3-Wattmeter method.
2) 2-Wattmeter method.
3) 1-Wattmeter method.

6. 3-PHASE WATTMETER METHOD

7. 2-PHASE WATTMETER METHOD

8. 1-PHASE WATTMETER METHOD

9. POWER FACTOR EFFECT ON 2-WATTMETER METHOD
 With Unity Power factor i.e. cosØ=1 & Ø=0
P1=√3VI cos(30-Ø) = √3VI cos(30-0) =3/2 VI
P2=√3VI cos(30+Ø) = √3VI cos(30+0) =3/2 VI
than P1+P2=3VI
 With 0.5 Power factor i.e. cosØ=0.5 & Ø=60
P1=√3VI cos(30-60) = √3VI cos(-30) =3/2 VI
P2=√3VI cos(30+60) = √3VI cos(90) = 0
than P1+P2= (3/2)VI
 With 0 Power factor i.e. cosØ=0 & Ø=90
P1=√3VI cos(30-90) = √3VI cos(-60) = √3/2 VI
P2=√3VI cos(30+90) = √3VI cos(120) = -√3/2 VI
than P1+P2= 0

10. ERROR DUE TO WATTMETER
CONNECTION

11. BIBLOGRAPHY
 Book by “ A Course in ELECTRICAL and ELECTRONIC MEASUREMENT and
INSTRUMENTATION “ by A.K.Sawhney.
 Book by “ Fundamental of ELECTRICAL ENGINEERING” by D.R.Nagpal.

12. THANK YOU
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