Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
82 Cards in this Set
- Front
- Back
TRUE OR FALSE
Pilot-duty devices are not normally used to switch horsepower loads. |
TRUE
|
|
TRUE OR FALSE
A motor starter would normally be classified as a primary control device. |
TRUE
|
|
TRUE OR FALSE
AC and DC contact current ratings are the same for a given switch. |
FALSE
|
|
TRUE OR FALSE
Mushroom head pushbutton operators are used for emergency stop push-buttons. |
TRUE
|
|
TRUE OR FALSE
A pushbutton assembly can have multiple contact block. |
TRUE
|
|
TRUE OR FALSE
Using maintained contacts in emergency stop pushbuttons prevents a motor control process from restarting until the maintained pushbutton is physically reset. |
TRUE
|
|
TRUE OR FALSE
Emergency stop pushbuttons must be of the maintained contact type |
TRUE
|
|
TRUE OR FALSE
The NEMA and IEC symbols for a pilot light are exactly the same. |
FALSE
|
|
TRUE OR FALSE
Push-to-test pilot lights can be energized from two separate signals of the same voltage. |
TRUE
|
|
TRUE OR FALSE
Drum switches are used for starting and reversing single phase motors that are designed for reversing service |
TRUE
|
|
Limit switches are usually actuated by hand.
|
FALSE
|
|
A micro switch is normally actuated by a permanent magnet.
|
FALSE
|
|
A flow switch is used to sense the height of a liquid.
|
FALSE
|
|
All selector switches operate with spring to provide momentary contact operation.
|
FALSE
|
|
An N.C. (normally closed) pushbutton makes a circuit when it is pressed and returns to its
open position when the button is released. |
FALSE
|
|
A micro switch is capable of operating with extremely small pressure on its operating lever.
|
TRUE
|
|
Temperature switches open or close when a designated temperature is reached.
|
TRUE
|
|
All pressure switches use only N.O. (normally open) contacts.
|
FALSE
|
|
Sensors are devices that are used to detect and often to measure the presence of something.
|
TRUE
|
|
A proximity sensor can not detect the presence of an object without physical contact.
|
FALSE
|
|
An inductive proximity sensor can be actuated by non-conductive materials.
|
FALSE
|
|
The standard detectable target for an inductive sensor is made of a ferrous material.
|
TRUE
|
|
The proximity switch leakage current is due to the switching characteristics of solid-state
devices. |
TRUE
|
|
Never directly operate a motor with a proximity sensor.
|
TRUE
|
|
Hysteresis is a desirable feature of a proximity sensor may prevent it from chattering.
|
TRUE
|
|
When the target enters the field of an capacitive proximity sensor the oscillator circuit stops
oscillating. |
FALSE
|
|
Photovoltaic (solar) cells produce DC voltages.
|
TRUE
|
|
Light shinning on a photo conductive (photo-resistive) cell will cause its resistance to
increase. |
FALSE
|
|
Color detection and discrimination are not possible with photoelectric sensors.
|
FALSE
|
|
The photoelectric sensor receiver is tuned to the emitter's modulation frequency, and will
only detect light pulses at the specific frequency. |
TRUE
|
|
The size of a target for a photoelectric sensor may be as small as a needle.
|
TRUE
|
|
In a through-beam scan sensor the emitter and receiver are housed in the same enclosure.
|
FALSE
|
|
An ultrasonic sensor requires a constant current bias current between two of its terminals.
|
FALSE
|
|
As the temperature of a thermistor with a negative temperature coefficient increases, its
resistance increases. |
FALSE
|
|
The basic operating principle of thermocouples is that the electrical resistance of metals
varies with temperature. |
FALSE
|
|
The operating temperature range of the IC temperature sensor is much lower than that of a
thermocouple. |
TRUE
|
|
A magnetic pickup sensor generates a voltage that is proportional to the speed at which it is
driven. |
FALSE
|
|
An encoder sensor is used to convert linear or rotary motion into an analog signal.
|
FALSE
|
|
Encoder sensors are used in applications such as robotic control where positions have to be
accurately determined. |
TRUE
|
|
The usual approach taken to measure fluid flow is to convert the kinetic energy that the fluid
has into some other measurable form. |
TRUE
|
|
The contacts of an electromechanical relay are switched by energizing the contacts.
|
FALSE
|
|
The normally open contact of a relay is closed any time the coil is energized.
|
TRUE
|
|
For DC solenoids, a non-laminated frame and plunger is acceptable.
|
TRUE
|
|
An AC solenoid rated for 120-V direct current if connected to a 120-V alternating current
source would draw lower than normal current. |
TRUE
|
|
Continuous duty is the same as 100% duty cycle
|
TRUE
|
|
If an AC solenoid sticks in the open position a burnout of the coil is likely.
|
TRUE
|
|
For most effective and efficient operation, the length of a solenoid stroke is kept as long as
possible. |
FALSE
|
|
A brush-less DC motor, like the brush type, can be driven by connecting it to a source of
direct current. |
FALSE
|
|
Generally, stepper motors are rated for less than 1 horsepower and are used in low-power
position control applications. |
TRUE
|
|
All open loop control systems operate without feedback.
|
TRUE
|
|
All servo motors operate using a closed loop control system.
|
TRUE
|
|
Which of the following would be classified as a pilot control device?
|
PRESSURE SWITCH
|
|
The _______ push-button makes a circuit when it is pressed and returns to the open position
when the button is released. |
N.O.
|
|
NEMA “types” enclosures are selected according to the
|
operating environment
|
|
Which of the following would be classified as a mechanically operated switch?
|
limit switch
|
|
When a metal object enters the high-frequency field of an inductive proximity sensor, it
causes |
a decrease of energy in the oscillator circuit
|
|
Which of the following scan techniques is best suited for long-range scanning?
|
Through-Beam
|
|
Which of the following scan sensors is best suited to detect shinny targets?
|
Polarized Retro-reflective
|
|
Fiber optic sensor systems
|
are immune to electrical interference
|
|
Which of the following sensors is designed to sense the strength of a magnetic field?
|
Hall-effect sensor
|
|
Which of the following converts rotational speed into an analog voltage signal?
|
Tachometer
|
|
Which of the flow-meters operates by measuring the changes of induced voltage of a
conductive fluid? |
Magnetic
|
|
The coil current for AC solenoids is primarily limited by the ______ of the coil.
|
inductive reactance
|
|
Which of the following would not be classified as an actuator?
|
Tachometer
|
|
Apprentice A says that the amount of puling or pushing force produced by a solenoid is
determined by the number of turns on the coil. Apprentice B says that is determined by the amount of current flowing through the coil. Who is correct? |
Both Apprentice A and Apprentice B
|
|
Solenoid valves are available to control ________ flow
|
ALL FLUIDS HYDRAULIC, PNEUMATIC AND WATER
|
|
A __________ solenoid valve blocks flow when the solenoid is De-energized and allows flow
when the solenoid is energized. |
normally closed
|
|
For a DC stepper motor the amount of rotation is directly proportional to the:
|
number of pulses
|
|
_______ switches are small assemblies designed for mounting on printed circuit boards.
|
Micro
|
|
The break-make push-button is used for ______________ of control circuits.
|
jog, start and stop
|
|
The _______________ is the part of the push-button assembly that is pressed, pulled, or
rotated by the person operating the circuit. |
e-stop
|
|
Selector switches require the operator device to be ____________ instead of pushed or
pulled to to actuate the attached contact block. |
turned
|
|
A float switch is used to sense the_______ of a liquid.
|
amount
|
|
Drum switches are used for starting and _____________ motors.
|
reversing / direction
|
|
The main difference between inductive and capacitive sensors is that capacitive sensors
produce an ______________ field instead of an electromagnetic field. |
electrostatic field
|
|
The two basic parts of a photoelectric sensor are the ________ and __________.
|
transmitter and reciever
|
|
The _________ technique refers to the method used by photoelectric sensors to detect a
target. |
scan
|
|
__________ readers are used for sorting of products on a conveyor.
|
Bar code
|
|
Hall-effect sensors are used to detect the _____________ and ______________ of a
magnetic field. |
proximity and strength
|
|
An ______________ sensor operates by sending high frequency sound waves toward a
target and measuring the time it takes for the pulses to bounce back. |
ultrasonic
|
|
An actuator is any device that converts an electrical signal into ____________
______________. |
mechanical movement
|
|
The stepper motor converts electrical pulses into discrete rotor movements called
____________. |
steps or resolution
|