Air 112 finial

6. The symbol for voltage is

"E" for electromotive force.

2. The symbol for current is

"I" for intensity.

4. The symbol for resistance

"R."

69. When the existing thermostat cable cannot be replaced or when an additional wire cannot be installed, an add-a-wire accessory may be used to take the place of the______________ terminals. 1. Honeywell THP9045A1023 Wiresaver Wiring Module.

"Y" and "G"

37. The primary side of a transformer is the________side of the transformer.

"input"

67. Cooling anticipation in a thermostat with a bimetal coil is performed during the _______cycle.

"off"

68. Heating anticipation in a thermostat with a bimetal coil is performed during the________ cycle.

"on"

36. The secondary side of a transformer is the _________side of the transformer.

"output"

1. Capacitors are connected between the __________terminals

"run" and "start"

3. Magnetic fields created by the ________ winding induce voltage in the _______ winding.

"run""start"

.2. The __________winding acts like the secondary coil in a transformer.

"start"

5. The voltage induced in the __________winding is greater than voltage impressed on the _____________

"start" "runwinding"

.6. Capacitors are subject to the higher voltage induced in the

"start" winding.

4. The ________ winding has more coils than the ________ winding.

"start""run"

55.. 1. Synchronous speed = (alternations x frequency) ÷ number of poles = RPM

(7200 ) ÷ Poles

15. The Watt input to an electric heater operating at 460-volts (1-phase) and drawing 7-amps equals

(W = volts x amps)3,220.

77. When voltmeter leads are connected across a switch (L1 to T1) in a contactor supplying a running motor, the meter will read

0-volts if the switch has good clean contacts.

14. One kilowatt (kW) equals

1,000 Watts.

74. Relays are generally used to control inductive loads that draw less than

1-15 amps

66. Wire used in the secondary circuit (thermostat circuit) of typical HVAC systems should be

18 gauge.

63. The voltage to ground of a "high-leg" on a 3-phase open Delta system will be approximately

208- volts.

13. Heat output (Btuh) of an electric resistive heater is ----x-----

3.413 x Watt input.

12. One horsepower equals

746 Watts.

84. an electronic control used for equipment operation and monitoring.

A direct digital control (DDC)

50. Motor that has the highest energy efficiency.

An ECM

1. The flow of electrons in a circuit.

Current

65. When the conductor in an AC circuit is wound into a coil, the resulting_______________ the supply voltage.

EMF opposes

5. Voltage is the electrical pressure impressed on a circuit and it is also known as

EMF or potential.

34. How many diodes are used to make a bridge rectifier connected to a center tap 3-wire transformer.

Four

35. How many diodes are used to make a bridge rectifier connected to a 2-wire transformer.

Four

72. A Wi-Fi thermostat communicates with the network by the thermostat's ________________address.

IP and/or Mac

8. The measurement of the opposition to the flow of alternating current through a circuit.

Impedance

48. Supply source connections are made to terminals on a contactor or motor starter.

L1, L2, and L3

3.The opposition to current flow.

Resistance

85. a material used as a semi-conductor.

Silicon

47. Load connections are made to _________________________ terminals on a contactor or motor starter.

T1, T2, and T3

10. Power input is measured in

Watts.

73. Excessive current can be caused by

a short circuit.

83. The most common type of transducer used with HVACR equipment creates a signal ______________.

based on pressure

29. A multimeter has a _________on-board that supplies a low voltage for measuring resistance.1. A multimeter set to measure resistance must never be connected to a capacitor until the capacitor has been discharged.

battery

56. To change the direction of rotation for a 3-phase motor?

change the position of any two supply wires.

59. When checking the windings of a single-phase motor, the _______ _______terminals will show the lowest resistance.

common to run

87. If a 24-volt, 20-Ohm, low-voltage contractor coil was wired in series with a 24-volt, 200-Ohm control relay coil, only the ____________ would operate.

control relay

33. A diode is used to

control the direction of electron flow.

53. The direction of rotation of a single-phase induction motor is determined by the direction of

current flow through the start winding.

79. When "reading" a schematic, the term "normal" refers to a circuit that is

de-energized.

80. When the temperature of a negative temperature coefficient (NTC) thermistor increases, its resistance will

decrease.

40. A step-down transformer

decreases voltage.

62. A device with overload protection used to control a motor is a

direct on-line starter.

41. The secondary voltage of a transformer is _____________to its number of windings compared to the number of windings in the primary of the transformer.

directly proportional

76. When contacts on a contactor become badly pitted,

either the contacts or the contactor must be replaced.

52. A solenoid valve coil operates on the principle of

electromagnetism.

49. An ______________ used in HVAC air-handlers is designed to provide proper airflow under a range of conditions.

electronically commutated motor (ECM)

44. When loads (resistors) are wired in parallel, the voltage drop across each load will

equal the applied source voltage.

71. On a split-system heat pump with an electronic data type control (communicating),________ wires are the minimum number of wires that need to be run between the indoor unit and the thermostat.

four

23. The color of the equipment safety ground wire is usually

green or it is bare.

24. The "hot" conductor in an alternating current circuit may be any color except

green or white.

57. The capacitor start-capacitor run (CSCR) motor provides

high starting torque and medium running torque.

7. The letter "Z" is used to represent

impedance in an AC circuit.

Current can arc through an open fuse if it is

in a circuit with voltage higher than the fuse's voltage rating.

70. When using an existing heating and cooling thermostat with only 4 wires (R, G, W and Y), common is provided to a new electronic thermostat through an

inactive circuit.

81. When the temperature of a positive temperature coefficient (PTC) thermistor increases, its resistance will

increase.

19. Current (amp) flow will increase when voltage impressed on a circuit is

increased on a resistive load

39. A step-up transformer

increases voltage.

1. Motors, solenoid coils, and transformers are examples of

inductive devices

This opposition to current flow is called

inductive reactance.

The synchronous speed of a motor and the number of its poles are?

inversely related

51. Inductive loads______________ use to do work.

magnetism

75. Contactors are rated according to the

maximum amperage through the contacts.

28. Capacitors are rated in

microfarads and volts.

20. An electron has a ________ charge.

negative

27. Circuit breakers and fuses are primarily used for protection from an

overload of current.

21. Like charges __________each other.

repel

60. On a good single-phase compressor motor, the _____ _______terminals have the highest resistance.

run to start

61. Resistance is the function of a multimeter used to bench check a motor for

shorts or open windings.

58. When checking the windings of a 3-phase motor, all three terminals should

show the same resistance.

43. The total resistance of a parallel circuit will be less than that of the

smallest resistance.

42. In a series circuit, the sum of voltage drop across each load will add up to the

source voltage.

32. Capacitors are always connected in series with the

start winding.

54. Single-phase motor speed is determined by the number of

stator poles.

31. A capacitor analyzer is used to measure

the capacitance of a capacitor.

86. A___________________ can generate a small DC electrical current.

thermocouple

46. A three-phase load requires _________electrical supply wires or lines.

three

82. A ______________converts the pressure signal in an electronic oil safety switch to an electrical signal.

transducer

45. A single-phase load requires____electrical supply wires or lines.

two

30. To discharge a motor capacitor prior to testing with a digital multimeter,

use a 15,000 or 20,000 Ohm, 2 to 5-Watt resistor across the terminals.

38. Transformers are rated according to

volt-amps (VA) at the secondary.

9. Ohms Law describes the relationship between

voltage (E), current or amps (I), and resistance (R).

11. Watts (P) in a single-phase circuit equals

volts (E) x amps (I).

26. Fuses are sized by .

volts and amps

78. A pictorial diagram is a drawing that illustrates .

where components are located and the wiring between these components

25. The neutral wire in a 120-VAC circuit must be

white.

64. If a clamp-on amp meter is clamped around both wires in a 2-wire circuit (such as 120-volts) when current is flowing, the meter will read

zero because the two magnetic fields cancel each other.

18. Generally, the maximum allowable (±) voltage supplied to a motor is? 1. 230-volts

±10 percent. x 0.90 = 207-volts 2. 230-volts x 1.10 = 253-volts

17. Generally, the maximum allowable (±) supply voltage to a building or an HVACR unit is? 230-volts =

±5 percent 0.95 = 219, 1.05 = 242-volts