Deck 9: Basic Control Circuits and Photodetectors

Question 1

Control circuits can be divided into two major types: three-wire control circuits and four-wire control circuits.

Answer 1

False

Question 2

Common voltage values for motor starter coils (in volts AC) are: 24, 120, 208, 240, 277, 480, and 560.

Answer 2

True

Question 3

Two-wire control circuits control the operation of three-phase motors by controlling the power applied to the motor ____.

A) starter coil
B) stator
C) shaft
D) bearing

Answer 3

starter coil

Question 4

____ voltage controls are simply controls that do not employ the use of a control transformer to change the voltage to a lower value.

A) Varistor
B) Line
C) Three-wire
D) Float

Question 5

Three-wire controls depend on a set of normally open contacts, generally called ____________________, maintaining, or sealing contacts.

Question 6

In a control circuit for a hot water boiler, a(n) ____________________-limit temperature switch will stop the burner if the water temperature should become excessive.

Question 7

What are some advantages of three-wire control circuits?

Question 8

What is the relationship between three-wire control circuits and momentary contact devices?

Question 9

Photodetectors can be used to sense the presence or absence of almost any object.

Question 10

Photo-operated devices fall into one of three categories: photovoltaic, photoemissive, and ____.

A) photomagnetic
B) photoresistive
C) photoconductive
D) alternative

Question 11

The transmitter section of a photodetector is the light source, which is generally a long life ____ bulb.

A) fluorescent
B) halogen
C) LED
D) incandescent

Question 12

Photoemissive devices emit ____________________ when in the presence of light.

Question 13

What is a cad cell?

Question 14

List some advantages of using a photodetector.