TPC 206 DC Equipment

Question 1

Which of the following cells has the shortest service life?

Answer 1

Lead Acid

Question 2

In the electroplating plating process, the object to be plated is made the…

Answer 2

Cathode

Question 3

Which device converts alternating current to direct current?

Answer 3

Rectifier

Question 4

A typical motor-generator set for a charging storge batteries uses a ______ on the equipment to shut off the charger after the correct amount of charging time.

Answer 4

timer unit

Question 5

Electroplating a piece of metal requires a _____ potential difference between the anode and the cathode an a _______ current.

Answer 5

Low; High

Question 6

A solenoid used for closing a valve or releasing a brake is usually made with a _____ shaped magnet.

Answer 6

C-T

Question 7

The movable magnetic arm of a relay is called the…

Answer 7

Armature

Question 8

A major cause of a noisy solenoid is loose

Answer 8

Laminations

Question 9

Incorrect seating of its plunger can cause a solenoid to

Answer 9

draw too much current

Question 10

To increase the service life of DC relay contacts that carry large inductive loads, a _____ can be connected in parallel with the load.

Answer 10

Diode

Question 11

Which part of a generator makes electrical contact between the brushes and the coils of wire in the armature?

Answer 11

Commutator

Question 12

In DC generation, the number of pulses during each rotation of the armature ______ with an increase in the number of ______.

Answer 12

increase; field poles

Question 13

A DC generator that supplies a nearly constant potential difference between terminals is called a _____ generator.

Answer 13

Compound

Question 14

Eddy currents in a DC generator cause _______ losses.

Answer 14

Magnetic

Question 15

The main parts of a DC generator are the field poles, brushes and brush rigging, commutator, frame, and…

Answer 15

Armature

Question 16

The field windings in a DC compound motor are connected so that _____ with the armature.

Answer 16

one is in parallel, and one is in series

Question 17

The only kind of DC motor to run faster under high load than under low load is a _____ motor.

Answer 17

Differential compound

Question 18

Another name for potential difference is

Answer 18

electromotive force

Question 19

One horsepower is equal to 550ft-lb per second or

Answer 19

745.7 joules per second

Question 20

Shunt, series, and compound refer to different kinds of

Answer 20

DC motors

Question 21

A winding that doubles back on itself in a drum armature is called a ______ winding.

Answer 21

Lap

Question 22

Which type of power loss varies with the speed of a DC armature and the volume or iron in the core?

Answer 22

Hysteresis loss

Question 23

Each DC armature coil is wound on a form, then insulated, _______ and baked.

Answer 23

varnished

Question 24

The two types of windings used on drum armatures are lap windings and ________ windings.

Answer 24

wave

Question 25

Preventative maintenance of an armature involves periodic inspections and tests to determine its condition, as well as _______ to preserve the insulation

Answer 25

Periodic cleaning

Question 26

A time-delay feature can be added to a magnetic overload relay in the form of an

Answer 26

oil dashpot

Question 27

The current at which a series lock out relay will close can be changed by adjusting the

Answer 27

size of the air gap

Question 28

A disk brake is designed to be mounted on the ______ of a motor

Answer 28

end bell

Question 29

Overload relays are usually of the ______ or _______ type.

Answer 29

Thermal; magnetic

Question 30

Whenever lockout relays are used in DC circuits, the controller is called a ______ starter.

Answer 30

Current-limiting

Question 31

An adjustable-voltage motor controller varies the potential difference applied to the motors

Answer 31

armature

Question 32

Controllers are rated by duty as _____ or ________.

Answer 32

Continuous; intermittent

Question 33

A NC overload relay contact in a magnetic motor controller is opened by means of a mechanism tripped by an overcurrent. In a manual motor

Answer 33

Mechanically

Question 34

Overload relays and contactors are not designed to protect a motor from extremely high ______ ; fuses and circuit breakers offer this kind of protection

Answer 34

current

Question 35

If a motor is to be started and stopped from several stations, all of the START pushbuttons are connected in ________ and the STOP push buttons in ______.

Answer 35

Parallel; series

Question 36

The emissions of electrons by heating is called _______ emission.

Answer 36

Thermionic

Question 37

Semiconductor failures caused by high temperatures usually occur

Answer 37

in a fractions of a second

Question 38

Which of the following lowers the peaks and raises the valleys in a rectifiers output?

Answer 38

Capacitor

Question 39

Four diodes in a diamond shaped circuit can deliver full-wave rectification in a _______ rectifier circuit.

Answer 39

Bridge

Question 40

Most automobiles use a _________ generator called an alternator, along with rectifiers, to charge and run the car's battery and electrical system

Answer 40

three-phase AC

Question 41

The part of an SCR that either allows or prevents the flow of electricity is called the

Answer 41

Gate

Question 42

An SCR in an AC circuit can be turned on earlier in the half-cycle in order to _______ the ______.

Answer 42

increase; power to the load

Question 43

Increasing the effective current and power level from an SCR controller to a DC motor requires

Answer 43

narrower intervals between pulses

Question 44

What turns on SCR on and off?

Answer 44

trigger pulses

Question 45

One very effective method of controlling an SCR in an AC circuit is called _______ control.

Answer 45

phase

Question 46

A sudden drop in the potential difference between terminals usually indicated an _________ circuit in the field winding of a DC _________.

Answer 46

open; generator

Question 47

Before installing a new field coil in a machine, you should

Answer 47

determine the polarity of the new coil

Question 48

If silver relay contacts become roughened or pitted, you should

Answer 48

do nothing

Question 49

Inspect the commutator risers on a dc armature regularly to determine the condition of the solder that secures the windings to the

Answer 49

segments

Question 50

Unless the manufacturer's instruction book tells you otherwise, brush pressure should be _______ psi per brush contact area.

Answer 50

1 1/2- 2 1/2