PHEP 23

Question 1

TRANSFORMERS PERMIT THE TRANSFER OF ELECTRICITY BETWEEN TWO CIRCUITS WHICH ARE

Answer 1

COMPLETELY INSULATED FROM EACH OTHER

Question 2

IN A TRANSFORMER THE WINDING WHICH RECEIVES THE ENERGY INDUCTIVELY IS CALLED THE

Answer 2

SECONDARY WINDING

Question 3

A POWER TRANSFORMER TRANSFERS ELECTRIC POWER FROM ONE CIRCUIT FREQUENCY AND VOLTAGE AND TO A SECOND CIRCUIT AT

Answer 3

A DIFFERENT VOLTAGE AND SAME FREQUENCY

Question 4

TRANSFORMERS ARE CLASSED AS STATIC AC MACHINES

Answer 4

TRUE

Question 5

A TRANSFORMER DEVELOPED 120 VOLTS IN ITS SECONDARY WHEN A 2400 VOLT SOURCE WAS CONNECTED ACROSS ITS PRIMARY. ASSUMING A PRIMARY CURRENT OF .25 AMPERES THE SECONDARY CURRENT IS

Answer 5

5 AMPS

Question 6

WHEN THE NUMBER OF TURNS OR VOLTAGE ON THE SECONDARY OF A TRANSFORMER IS GREATER THAT THAT OF THE PRIMARY IT IS KNOWN AS A

Answer 6

STEP-UP TRANSFORMER

Question 7

TRANSFORMERS HAVING ONLY ONE WINDING ARE CALLED

Answer 7

AUTOTRANSFORMERS

Question 8

THE SECONDARY OF A POTENTIAL TRANSFORMER SHOULD NEVER BE

Answer 8

SHORT CIRCUITED TO REMOVE THE DEVICE IT OPERATES FROM SERVICE

Question 9

WHAT IS THE INDUCED SECONDARY VOLTAGE OF A TRANSFORMER HAVING A PRIMARY WINDING OF 3000 TURNS AND A SECONDARY WINDING OF 300 TURNS WHEN CONNECTED TO A 24OO VAC SOURCE

Answer 9

240 VOLTS

Question 10

IN A CORE TYPE TRANSFORMER

Answer 10

A SECTION OF THE PRIMARY AND SECONDARY WINDINGS ARE WOUND AROUND EACH LEG OF THE CORE

Question 11

CURRENT TRANSFORMERS ARE INSTRUMENT TRANSFORMERS USED TO

Answer 11

STEP CURRENT DOWN

Question 12

HYSTRERESIS CAN BE EXPLAINED AS

Answer 12

FRICTION OF THE MOLECULES DUE TO ALTERNATING CURRENT

Question 13

WHEN A TRANSFORMER’S WINDINGS ARE CONNECTED WYE

Answer 13

THE LINE CURRENT WILL BE THE SAME AS THE PHASE CURRENT

Question 14

A SERIES STREET LIGHTING SYSTEM REQUIRES WHAT TYPE OF TRANSFORMER

Answer 14

A CONSTANT CURRENT TRANSFORMER

Question 15

THE RATING OF A TRANSFORMER IS USUALLY GIVEN IN

Answer 15

VA,KVA,MVA

Question 16

BUSHINGS ARE USED ON TRANSFORMERS TO

Answer 16

SERVE AS ENTRANCES INTO THE TRANSFORMER FOR THE MAIN LEADS

Question 17

THE CONSERVATOR SYSTEM IS USED ON TRANSFORMERS TO

Answer 17

PRESERVE THE DIELECTRIC STRENGTH OF THE TRANSFORMER OIL

Question 18

THE SECONDARY OF A CURRENT TRANSFORMER SHOULD NEVER BE

Answer 18

OPENED TO REMOVE THE DEVICE IT OPERATES FROM SERVICE

Question 19

IN AN ENERGIZED TRANSFORMER IRON LOSSES ARE PRESENT EVEN IF THERE IS NO LOAD ON THE SECONDARY

Answer 19

TRUE

Question 20

IN A TRANSFORMER A_______ MUST ALWAYS EXIST BETWEEN THE PRIMARY AND THE SECONDARY FIELDS TO MAINTAIN THE REQUIRED PRIMARY CURRENT TO SUPPLY THE TRANSFORMER LOSSES AND SECONDARY LOAD

Answer 20

BALANCED CONDITION