Deck 12: Ventilating, Air Conditioning, and Other Facilities

Question 1

Low-pressure refrigerant flows through the to provide cooling for the motor of a hermetically sealed compressor.

A) valves
B) rotor
C) load
D) stator winding

Answer 1

D

Question 2

Whenever the specific area is cooled to the desired temperature, a(n) opens the control circuit to the motor controller and the air movement stops until the area again requires cooling.

A) fan coil
B) thermostat
C) fin tube coil
D) overload protector

Answer 2

B

Question 3

What precautions must be taken when installing drive belts?

Answer 3

After the raceway is installed, the electrician usually is responsible for aligning the motor and adjusting the drive belts. The drive for the cooling unit requires three V-belts. It is recommended that the three belts be purchased as a set so that they all have the same length. The belts should be installed only after the motor is loosened from its base and moved closer to the fan sheave. The belts should not be pulled on over the sheaves because the belt fabric can be damaged. The motor should be placed so that the sheaves are in perfect alignment. The motor is then moved to tighten the belts.

Question 4

In most instances, the rated-load current is at least equal to 64.1 percent of the hermetic refrigerant motor- compressor's current.

A) maximum continuous
B) direct drive
C) branch-circuit selection
D) oscillating

Question 5

What is oil mist and why is it detrimental?

Question 6

In the precipitator, wires made of which metal give the particles a positive charge?

A) aluminum
B) palladium
C) tungsten
D) silver

Question 7

What is the maximum deflection force in pounds for a belt in the cross-section class D?

A) 2.5
B) 6
C) 13
D) 25

Question 8

What is the basic construction of a precipitation unit?

Question 9

The correct tension for a belt in the cooling unit drive can be determined from the .

A) maximum continuous current
B) rated-load current
C) motor manufacturer's literature
D) nameplate

Question 10

The exhaust blower unit consists of a three-horsepower, three-phase, 208-volt motor driving a propeller-type fan through a(n) drive.

A) V-belt
B) direct
C) O-ring
D) conveyer

Question 11

One method of removing oil mist is by the use of units.

A) precipitation
B) coolant
C) rotor
D) stator

Question 12

What overload protection is required for the motors of the fan coil units in the cooling equipment?

Question 13

A(n) converts high-voltage ac into high-voltage dc.

A) rectifier
B) transistor
C) capacitor
D) inductor

Question 14

The current draw of a precipitator is .

A) zero
B) very low
C) very high
D) widely variable and dependent on level of pollution

Question 15

The main parts of a precipitator are the , collector cells, and power supply.

A) fin tube
B) ionizer
C) cooler
D) oscillator

Question 16

When hermetic refrigerant motor-compressors are designed to operate continuously at currents greater than 156 percent of the rated-load current, the nameplate is marked with current.

A) maximum continuous
B) direct drive
C) branch-circuit selection
D) oscillating

Question 17

The current is determined by the manufacturer of the hermetic refrigerant motor compressor by testing at rated refrigerant pressure, temperature conditions, and voltage.

A) maximum continuous
B) direct drive
C) rated-load
D) oscillating

Question 18

The manufacturer determines the by multiplying the rated-load current, or the branch-circuit selection current of the hermetic refrigerant motor-compressor, by 125 percent.

A) maximum continuous current
B) maximum overcurrent
C) maximum circuit ampacity
D) minimum circuit ampacity

Question 19

The protective device is determined by multiplying the rated-load current, or the branch-circuit selection current of the hermetic refrigerant motor-compressor, by 225 percent and then adding all concurrent loads such as electric heaters, motors, and so on.

A) branch-circuit
B) rated-load
C) maximum continuous current
D) maximum overcurrent

Question 20

How are pollutants actually trapped by the precipitator?