Unit 17 Quiz Part 2 Flashcards by Stirling Ragasa

Q

As temperature increases, a PTC’s resistance will _______.

A

Increase

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Hermetic compressors may be cooled internally by _____ and/or externally by ____.

A

1.Vapor
2. Air

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Pulsating DC voltage is produced in the ______section of the VFD.

A

Rectifier

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Four types of devices are commonly used to disconnect the start capacitor from the circuit. What are the four devices?

A

Centrifugal, potential relay, current relay, and PTCR

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: DC motors with brushes cannot be used in hermetic compressors.

A

True

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: To measure the resistance of a PTCR, wait until it cools to room temperature and then check its resistance.

A

True

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: The run and start winding resistance in a three-phase motor should add up to the resistance measured from the start and run winding.

A

False

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: Transistors can be found in the rectifying section of the VFD.

A

False

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: The term “soft starting” for a VFD means a motor is slowly ramped up to speed instead of starting at full speed and drawing locked rotor amperage.

A

True

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: The capacitors in parallel filter the voltage wave and the inductor filters the current wave in a VFD.

A

True

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: A three-phase dual voltage motor is wired in series when using low voltage configuration.

A

False

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

True or false: A 230V capacitor can be used for a 440V application.

A

False

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

Transistors

A

S

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

Diodes

A

R

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

Inductor

A

F

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

SCR

A

R

How well did you know this?

1

Not at all

2

3

4

5

Perfectly

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

Convert DC to AC

Study These Flashcards

A

S

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

Capacitor

Study These Flashcards

A

F

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

PWM

Study These Flashcards

A

S

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

Converts AC to DC

Study These Flashcards

A

R

Q

Match the component/function with the proper section of a VFD. Switching (S), Filter (F), Rectification (R).

Inverter

Study These Flashcards

A

S

Q

Holds the motor components in place and provide a means for securely mounting the motor itself.

Study These Flashcards

A

Housing

Q

Has less windings and resistance than the start winding.

Study These Flashcards

A

Run windings

Q

Winding resistance is the same in each winding.

Study These Flashcards

A

3-phase motor

Switching section of a VFD.

Inverter

The maximum EMF that the relay’s coil can tolerate continuously without overheating and opening the circuit.

Continuous coil voltage

Electronic device in a motor circuit that is used to control motor speed for variable speed motors.

PWM

The speed at which power devices switch on and off.

Switch/carrier frequency

Uses electronics to commutate the rotor instead of brushes.

ECM motor

More efficient to reduce the speed of a motor than to stop and start.

Variable speed motor

Very little starting torque and can be reversed by flipping the stator.

Shaded pole motor

Why can’t you have a centrifugal switch in a hermetic compressor?

An ARC may occur that would result in a explosion potentially occurring spark degrades refrigerant (sludge, acid)

How is a typical open electric motor cooled?

Air cooled

Motor wire configurations may use 3,6,9 or 12 lead wires. What wire leads can be configured in either the wye or delta configuration for dual voltage operation?

9 & 12

What wire leads can only be configured for single voltage operation?

3 & 6

Extra Credit 1. When joining Steel pipe, approximately how many perfect threads and imperfect threads for each joint?

7 perfect & 2/3 imperfect

Extra credit: 2. Nominal tubing used for plumbing is sized by its ____ diameter while ACR tubing is sized by its ____ diameter.

Inner Outer

Extra Credit: 3. What type of fastener is used to hold a component either onto a shaft or inside some type of housing?

Cotter pin Retaining/snap-ring Hairpin

Extra Credit: 4. When charging a chiller, refrigerant vapor is introduced into the system before charging with liquid refrigerant because _____.

Liquid charged into a deep vacuum will cause the refrigerant to boil and may lower temperatures enough to freeze the water in the tubes

Extra Credit: 5. ______ + _________+________= acids

Heat + moisture + refrigerant = acids