Chapter 13 - Controls & Sensors Flashcards
AC motor starters connect an AC motor to and disconnect it from an electrical power source.
True
AC starters employ two basic components, a contactor and an overload
True
Contactors are non-magnetically operated.
False
Manual starters are the most widely used in the USA for motors over 2 HP
False
Starters designed to meet NEMA and IEC standards differ in three important characteristics-ratings, life, and overload types.
True
Three-phase motors are reversed by interchanging any two of three power leads to the motor.
True
Solid-state starters use an intelligent regulator module similar to those used in adjustable-speed DC drives.
True
Solid-state starters can use current-limit ramping or tachometer feedback to produce different acceleration and deceleration characteristics.
True
Solid-state starters have an “energy-saver” function.
True
Class H fuses are not renewable.
False
Motor controllers often contain relays, push buttons, and manually operated switches.
True
The size of a PLC memory is defined in so many “K”
True
PLCs are unable to work with any form of local are network (LAN) communication
False
All personal computers come with an I/O structure.
False
Sensors are devices that respond to a physical stimulus such as heat, light, pressure and flow.
True
Tachometer-generators are used to measure speed of light.
False
Encoders are used for both position and speed feedback.
True
Message displays provide information in response to various control events.
True
Limit switches translate motion into switch actuation.
True
Bubble sensors are popular for water and waste treatment applications.
True
Piezoresistive sensors are based on the principle that resistance of the same element changes with humidity.
False
LVDT is the abbreviation for low voltage digital transformer.
False
Photoelectric sensors produce a voltage when exposed to light.
True
Vision systems integrate integrate industrial computers with video cameras that provide data about the light it receives.
True
PLCs and computers have
user programmability, Internal bus systems, Inputs and outputs, recallable memory (all of the above)
Optical encoders include
Incremental and Absolute (A and C above)
Control devices that can leak a small amount of current when turned off include
Solid-state switches
Relay contacts typically are rated for
10A
PLC’s are classified by the ability to
Add and subtract, multiply and divide, compare values and Diagnose (all of the above)
Character displays can use
Light-emitting diodes (LEDs), Light-counting diodes (LCDs) Electrolyte diodes (ELDs) (all of the above)
Incremental encoders have one limitation
A power interruption causes a loss of position information
The following considerations are important when selecting a proximity sensor
Sensing speed required, level of contamination potential, the type of enclosure required, target materials (all of the above)
Strain gauges and LVDTs are used to measure
Force, weight, tension
Sensors are devices that respond to physical stimulus such as
Heat, light, pressure, flow (all of the above)
These devices are used for both position and feedback.
Encoders
These switches translate motion into switch actuation
Limit
These sensors produce a voltage when exposed to light
photoelectric
_______ systems integrate industrial computers with video cameras that provide data about the light it receives.
Vision
