Page 466 - Basic Electrical Engineering

b. V ph = V L
c. 3I = I L
ph
d. I = I .
ph
L
4. In a delta-connected system the relationship between the phase and line quanties are

a. V ph = V L

b. V ph = V L
c. I = I L
ph
d. I = I .
ph
L
5. Line currents drawn by a three-phase star-connected bnalanced load is 12 A when connected
to a balanced three-phase four-wire system. The neutral current will be

a. 36 A
b. 4 A
c. 0 A
d. 3 A.

6. Power in a balanced three-phase system circuit is

a. 3 V I cos ϕ
p p
b. 3 V I cos ϕ
L L
c. V I cos ϕ
p p
d. V I cos ϕ.
p p
7. Reactive power of a three-phase circuit is

a. V I sin ϕ
p p
b. V I sin ϕ
L L
c. V I cos ϕ
L L
d. V I .
L L
8. power in a single-phase ac circuit can be expressed as

a. V I cos ϕ
p p
b. 3 V I cos ϕ
p p
c. V I cos ϕ
p p
d. V I cos ϕ.
p p
9. One single-phase wattmeter can be used to measure power in a three-phase circuit when