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Flashcards in Study info Deck (85):
1

T or F After a DC test has been completed on a long cable, it is most important that the conductor under test be grounded for a sustained period of time.

Answer: True

2

T or F Single conductor, 750 kcmils core-flex services are normally grounded at both ends.

Answer: True if high voltage otherwise False

3

T or F Before an SCR is fired, it acts like an open circuit

Answer: True

4

T or F An SCR can only be fired if the polarity on the anode is negative with respect to the cathode.

Answer: False

5

T or F On a DC drive with the potentiometer adjusted so that the DC motor is turning at minimum speed, the firing angle of the SCR is zero degrees.

Answer: False

6

T or F High voltage DC lines are not subject to corona.

Answer: False

7

T or F Single conductor 25 KV URD cables are normally tested at 55 KV.

Answer: False

8

T or F the autotransformer can be used for starting large motors to increase Torque.

Answer: False

9

T or F Dynamic braking on a three-phase AC motor is impossible.

Answer: False

10

T or F Three-phase rectifiers always employ six diodes in their construction.

Answer: False

11

T or F P.I.V. Is a term used when talking about the forward voltage drop of solid-state devices.

Answer: False

12

T or F Three-phase bridge rectifiers are normally connected star supplies for full wave operation.

Answer: False

13

T or F Single conductor URD cables are normally grounded at both ends.

Answer: True

14

T or F By code, high voltage means 750 Volts or over

Answer: False 751 Volts

15

T or F On a stress cone the finishing tape is normally wrapped by starting at the lug and taping toward the cone.

Answer: False

16

T or F The total capacitance of a circuit containing a 20 uF and a 30 uF capacitor connected in series is 50 uF.

Answer : False

17

T or F There is more line current drawn by a fully loaded five horse power 0.9 PF motor than a 0.7 PF horse power motor.

Answer : False

18

T or F DC hipot testing is normally done after the cable has been in service for 5 years.

Answer: False

19

T or F The power factor of a three-phase squirrel cage motor is better at no load than at full load.

Answer: False

20

T or F URD concentric neutral high voltage cables are used only on three-phase power circuit.

Answer : False

21

T or F Hypot testing is the only method of testing high voltage equipment.

Answer : False

22

T or F “Pot heads “ are found only on three conductor P.I.L.C. cable.

Answer: Fasle

23

T or F A fully charged lead acid batter will have a relative density of 1.125

Answer: False

24

T or F With a large hard disk drive it is not necessary to back up any file.

Answer: False

25

T or F In a nurse call system the reset button is located where the incident has happened.

Answer: True

26

T or F Windows XP is an operating system that is newer than Windows 8 .

Answer: False

27

T or F Connecting a capacitor in parallel with an inductive AC load will change the line current without affecting the load current.

Answer: False

28

T or F The speed of a synchronous motor can be controlled by changing the rotor resistance.

Answer: False


Nope it's false

29

T or F The purpose of a thermocouple in a gas furnace is to indicate the presence of a pilot flame.

Answer: True

30

T or F The secondary voltage of a delta/wye three phase transformer is in phase with the primary voltage.

Answer: True

31

T or F A resistor has 3 orange bands, it is a 33 kilohms resistor.

Answer: True

32

T or F Every 12 revolutions an 8 pole field will generate 48 cycles in a stator winding.

Answer: True

33

T or F An alternator with 6 pairs of poles generating at 60 Hz would be driven at 600 RPM.

Answer: True

34

T or F The power of a half-wave single-phase DC circuit can be determined by : ( EDC X 1.11)X(IDC X 1.11) =watts

Answer: False

35

T or F An “Inductive” load is supplied from an AC source. The current (I) maximum is 310 amps. Voltage (E) maximum is 140 Volts. The effective power In KW supplied to the load is 21.7 KW.

Answer:True

36

T or F Reactors may be used for limiting fault current surges.

Answer: True

37

T or F A capacitor put across a set of contacts used in an inductive circuit will act as an arc suppressor.

Answer: True

38

T or F A 20 kilohms/voltmeter has an insertion circuit resistance of 6 megaohms when switched to a 300 volt scale.

Answer: True

39

T or F In a series DC circuit containing resistance and capacitance, increasing the capacitance increases the charging time.

Answer: True

40

T or F To change rotation of any three phase induction motor you simply interchange any two rotor leads.

Answer: False

41

T or F In a FA system, an E.O.L. ( end of line resistor) is required for electrical supervision.

Answer: False

42

T or F Power cords have only one proper end to which a power plug may be installed.

Answer : True

43

T or F The volt amps at the primary of a transformer are greater than the wattage is the secondary.

Answer: False

44

T or F All three-phase AC motors must have overload protection set at 125% of full load current.

Answer: False

45

T or F A 20 and 30 uF capacitor are parallel connected to a 200 volt high frequency line. If the total line current to the capacitors is 3 amps, there will be close to 1.9 amps in the 30 uF branch.

Answer: True

46

T or F The anode is a silicon diode is symbolized by a bar.

Answer: False

47

T or F Pull boxes used in straight runs of #35 or larger conduit containing 3- #3 R 90 XLPE, shall have a length of at least six times the internal diameter of the conduit.

Answer: True

48

T or F Amortisseur windings are used to prevent hunting of synchronous alternators.

Answer: True

49

T or F In general semi conductor material has a positive temperature coefficient.

Answer: False

50

T or F A thermistor is a power resistor.

Answer: True

51

T or F It is possible to read the wattage of a balanced three-phase three-wire load employing the two wattmeter method.

Answer: True

52

T or F In a heat pump the flow of refrigerant can be reversed to supply heating as well as cooling.

Answer: True

53

T or F When synchronizing AC alternators with the three dark method a considerable difference in voltage could exist even though the lights are dark.

Answer: True

54

T or F When the frequency to a three-phase Induction motor is reduced by 10% the motor speed will be reduced by 10%

Answer: True

55

T or F Two 100 KVA transformers connected in open delta will deliver a maximum of 115.4 KVA to a load.

Answer: False

56

T or F The capacitors in a rapid start ballast are for radio interference and power factor correction only

Answer: False

57

T or F A diverted rheostat is connected in a series with the series field of a DC generator.

Answer: False

58

T or F Field discharge resistors in a synchronous motor starter are used to limit field current.

Answer: True

59

T or F Disconnects are used with high voltage circuit breakers to provide visible proof of voltage isolation.

Answer: True

60

T or F The purpose if an end of line resistor (EOL) in a supervised fire alarm system is to short circuit the detection devices.

Answer: False

61

T or F Line loss is found by multiplying the voltage drop and the line current.

Answer: True

62

T or F The most common word size for a PLC is 2 bytes.

Answer: True

63

T or F A PLC user memory is factory configured and cannot be changed.

Answer: True

64

T or F A thermocouple is an example of a discrete I/O

Answer: False

65

T or F Fail safe wiring refers only to motor control stop circuits.

Answer: False

66

T or F A PLC can use a 4-20 ma signal as an input ?

Answer: True

67

To reverse the direction of rotation for a single-phase, shaded pole motor, the :

A.) stator must be removed and turned over
B.) shading coil must be interchanged
C.) starting winding must be interchanged
D.) running winding must be interchanged

Answer: A. Stator must be removed and turned over.

68

The single-phase, AC series motor has characteristics which are very similar to the :

A.)universal motor
B.)wound rotor motor
C.) AC squirrel-cage motor
D.) AC induction motor

Answer: A. Universal motor

69

Which of the following statements is true in Boolean algebra:

A. A•B= A+B
B. — — = ———
A•B A•B
C. ——
——
A= A
D. —— + —- = ———
A. B A+B

Answer : C. A = —

A

70

The type of light transmitted in most fibre-optic communications system is:

Answer: Infrared

71

The greatest drop output voltage will occur if full load is taken from an alternator at:

A.)unity power factor
B.) high leading power factor
C.) low leading power factor
D.) high lagging power factor

Answer: B. High leading power factor .

72

When a capacitor is charged, the dielectric has :
A.) a surplus of electrons
B.) a deficiency of electrons
C.) the same number of electrons

Answer: C. The same number of electrons.

73

The best method of controlling the speed of a series motor is to:
A.) change the load
B.) vary the current to the motor
C.) vary the position of the brushes
D.) add a brake drum

Answer: B. Vary the current to the motor

74

A DC series motor will run away if the load is removed while the power is still being applied. This is a result of:
A.) loss of C.E.M.F
B.) low input voltage to the armature
C.) increased C.E.M.F. acting to weaken the field.
D.) high voltage developed across the field.

Answer: A.loss of C.E.M.F.


Nope it's C

75

In a delta-star step down transformer bank each transformer has a turns ratio of 2:1 The primary voltage is 480 Volts and the unit supplies a 10 KW, three-phase load at unity power factor. The secondary line current is:

A.) 13.9 amps
B.) 12 amps
C.) 24.1 amps
D.) 36 amps

Answer:C 24.1 amps

76

HRC fuses are filled with silica to:

A.) make the fuse operate at a lower temperature
B.) speed the rate at which the fuse element melts.
C.) reduce arcing when the fuse element melts
D.) to give a longer time delay

Answer: A. make the fuses operate at a lower temperature.



Nope it's C

77

If the output voltage of an alternator drops due to heavy loading it is generally brought back up by :
A.) increasing the resistance is the field rheostat
B.) decreasing the resistance of the field rheostat
C.) increasing the speed
D.) decreasing the speed

Answer: C. Increasing the speed


Might be B

78

A receptacle located in a hospital and connected to the essential electrical equipment shall be :

A.) of the Class “A” GFCI type
B.) approved as hospital grade displaying a green dot or triangle
C.) orange in colour
D.) red In colour

Answer: D. Red in colour

79

Starting resistances of DC motors are connected:

A.) In the series with the line
B.) In series with the armature
C.) In series with the shunt field
D.) In parallel with the series field

Answer: B. In series with the armature

80

To determine the state of charge of a nickel-cadmium battery, you could use a :

A.) voltmeter with a load connected to the battery
B.) hyrdrometer
C.) ammeter with a load connected to the battery
D.) voltmeter to measure the open-circuit voltage

Answer: B. Hydrometer

81

The specific gravity of the electrolyte in a fully charged nickel-cadmium battery is usually about:

A.) 1050
B.) 1100
C.) 1150
D.) 1200

Answer: D. 1200

82

Emergency systems should be tested:

A.) once a week
B.) once a month
C.) Once every 6 months
D.) Once a year

Answer: B. Once a month

83

A NO-LOAD terminal voltage of a fully-charged, six cell nickel cadmium battery would measure as:

A. 6 volts
B. 12 volts
C. 13.2 volts
D. 7.2 volts

Answer: D 7.2 volts

84

A disadvantage of a PV (photovoltaic) system is :

A.) Initial Cost
B.) Maintenance Cost
C.) Reliability
D.) Mobility

Answer: A. Initial Cost

85

The following loads are fed from a 600 volt, three-phase, 60 Hz source: 10 kW of electric heating, 20 kW at 0.6 Pf lagging, 15 KVA at 0.8 Pf leading, and 50 KVA at 0.65 Pf lagging.

Total KVA

Total KVARS

System PF

Total KW

Line Current

The KVARS rating of a capacitor bank to bring the system power factor to 0.955

The capacity of ONE capacitor in microfarads connected Delta _____ WYE________

Answers Total KVA =93 KVA
Total KVARS= 55.67 KVars
System PF = .8012
Total Kw = 74.5 KW
I Line =89.49 A
KVARS to bring PF to .955 =32.53 KVAr
Capacitor connected Delta = 79.967 uF
WYE= 239.1uF