3 Phase

Question 1

Wye connections are characterized by?

Answer 1

The fact that one terminal of each of the devices is connected together

Question 2

In a wye connection, phase voltage is less or more than line and by what

Answer 2

Phase voltage is less than line by root3

Question 3

In delta, phase voltage is what to line voltage

Answer 3

Phase and line the same in delta

Question 4

Line current in delta is what to phase current

Answer 4

Line current in delta is more than phase by root3

Question 5

Wye load has a voltage of 480v , what is the voltage dropped across each phase ?

Answer 5

480/root3 = 277.13 Ephase

Question 6

Delta connection has a voltage of 560V how many colts dropped across each phase?

Answer 6

El =EP in delta = 560

Question 7

A c generators are commonly referred to as?

Answer 7

Alternators

Question 8

The voltage is induced in the part of the alternator called?

Answer 8

Armature

Question 9

Between maximum positive and maximum negative values of a single phase alternating current or voltage the difference is ?

Answer 9

180

Question 10

Between maximum positive and maximum negative of one phase of a three phase alternating current or voltage , difference of?

Answer 10

180

Question 11

In wye connected balanced 3 phase system the line current values and the winding current values are

Answer 11

The same

Question 12

In a balanced delta system, the line and coil voltages are

Answer 12

The same

Question 13

A 3 phase a c generator is connected in WYE . Each 3 coil windings rated 4000 V A and 120 bolts the line voltage would be?

Answer 13

208. 120xroot 3

Question 14

3 phase generator connected in WYE . Voltage of each phase or coil would be?

Answer 14

277. 480/root3

Question 15

In a delta system line voltage to coil voltage is what ?

Answer 15

Equals coil voltage

Question 16

In a 3 phase WYe circuit the power in WATTS is equal to?

Answer 16

Cosine/_ x ELine x I Line x root 3

Question 17

Improvement of the power factor of a three phase circuit has this effect on the a c circuit

Answer 17

Decreases volt amps

Decreases current for the same power output power out

Question 18

Line to line voltage of a c wye generator is 208 what’s voltage rating of each winding

Answer 18

120. 208/ root 3

Question 19

In three phase power systems , the delivered power…?

Answer 19

Never falls to 0

Question 20

The three phase connection which one end of each of the windings are connected together is called the

Answer 20

WYE connection

Question 21

In a three phase connection, voltage measured from one external voltage connector to another is the ________ voltage

Answer 21

Phase

Question 22

In a 3 phase connection the current that flows in the winding is the ______ current

Answer 22

Phase

Question 23

Line current and phase current are the same in?

Answer 23

WYE configuration

Question 24

Three phase connection which all three of the coils are connected end to end to form a closed loop is the _______ connection?

Answer 24

Delta

Question 25

Multiplying apparent power by the power factor gives you what?

Answer 25

True power

Question 26

Calculating power ina. Three phase circuit, the product of line current and power factor are multiplied by what?

Answer 26

Square root 3

Question 27

If a 3 phase load is purely reactive then power calculated has units of?

Answer 27

Vars