Automated Controls Flashcards
What does IoT stand for
Internet of things
What is an advantage and disadvantage of an automated system
-Ongoing labour is reduced
-initial labour is usually higher
What are three characteristics of an open loop system
-requires an operator
-not self correcting
-not feedback
What are three characteristics of a closed loop system
-not operator
-is self correcting
-has feedback
Advantages of an open loop system
-low initial cost
-easy to install
-simple to troubleshoot
Disadvantages of an open loop system
-ongoing labour
-error can occur (human)
Advantages of a closed loop system
-self correcting
-reduced ongoing labour
-reduced error
-higher performance
Disadvantages of a closed loop system
-high initial cost
-expensive to install
-more complex to troubleshoot
Briefly describe what the error signal does
Sees the difference between the setpoint and the sensor signals
What are the 5 most common process variables
-temp
-level
-pressure
-rpm
-light
What are the two modes within a closed loop and an open loop
-dis-continuous
-continuos
Describe a characteristic of discontinuous control
Discontinuous control uses actuators which are either on or off
-digital sensor
What is a characteristic of a continuous control
The actuator is variable and is proportional to the difference of the sensor and setpoint
Is continuous control analog or binary?
Analog
Is discontinuous control analog or binary
Binary
The process variables of a continuous control is dependent upon?
-resolution of the sensors
-performance of the actuators
Compliance of the process variable
What does P & ID stand for
Piping and instrumentation drawings
What does PID stand for
Proportional integral derivative
Explain what each letter represents in PID
P proportional- how big is the error
I integral- how lang has the error been present
D derivative- how fast is the error changing
Describe what a transducer does
Converts one form of energy to another
What are most sensors
They are transducers
What do active transducers do
Generate output without external power
What do passive transducers do
Do not generate an output
Only physically or electrically change
External power supply required
Sensors often have two components what are they
Primary element
Secondary element
What does a sensors primary element do
Convert process variable into a format that can be measured
What does a sensors secondary element do
Convert the primary element into and electric change
What does lvdt stand for and how does it work
Linear variable differential transformer
Shows output voltage by moving a core through and inductor
What’s the difference between an lvdt and lvdt discriminator circuit
You can tell if the core has moved up or down
What is a low pressure pressure/vacuum sensor
Bellows
What is a pressor sensor with more pressure than a bellows
Diaphragm
What pressure sensor has the highest pressure
Bourdon tubes
What are two types of strain gauges
Bonded wire
Piezoresistive
What strain gauges is more sensitive
Piezoresistive
What are the different types of flow sensors 4
Flow switch
Manometer(atmospheric pressure gauge)
Turbine flow meter
Magnetic flow meter
What are the types of level sensors 4
Floats
Switches
Conduction
Ultrasonic
What kind of temp co does an RTD have
Positive
What kind of temp co does a thermometer have
Negative
What are temperature sensor common outputs 5
4-20mA
10-50mA
1-5v
1-10v
3-15psi
Is an ic a type of RTD T or F
True
What does ADC stand for
Analog to digital converter
What is a controlled variable
The parameter that is desired to be changed
What does DAC stand for
Digital to analog converter
What does DCS stand for
Distributed control system
What does DDC stand for
Distributed digital
Control
What are the common first letters of a balloon and what do they represent
T temperature
L level
F flow
P pressure
What are the balloon letters after the first letter and what do they represent
I indicator
R recorder
C controller
V valve
A alarm
What device is formed when several thermal couples are connected together in series
Thermopile
What is a radiation pyrometer used for
To measure heat loads of high temperature
Give two applications where thermal couples are used
Furnace
Gas fireplace
Identify three types of electrical equipment that use bimetallic sensors
Thermostat
OLR
CB’s
What is the most common material for RTDs
Platinum and nickel
What kind of temp coefficient does a RTD have
Positive
What kind of temp coefficient does a thermister have
Negative
What is a common application for thermisters
Sense motor winding temperature
What are two differences from RTDs and thermisters
RTD use bimetallic and have a positive temp coef
Thermisters uses semiconductor and has a neg temp coef
What is the function of a bifillar winding
Eliminate inductance
RTDs and thermisters both indicate a change in ____________ for a change in ______________
Resistance
Temperature
Bellows and diaphragm are both used to convert pressure in what
Motion
What advantage does a magnetic flow meter have over a turbine flow meter
No moving parts
Less maintenance
What basic principle is utilized by a magnetic flow meter
Faraday’s law
What are 5 common types of electrical actuators
Solenoid
Motor
Clutch
Stepper motor
Encoder
What are the 5 parts to the eddy current coupling
External coil exciter
Drum
Coil
Input shaft
Output shaft
How could you increase the speed on the output shaft of an eddy current coupling
Adding more excitation to coil exciter
What causes an eddy current coupling to produce a good amount of heat
Eddy currents
What two methods are used to cool an eddy current coupling
Air
Liquid
What is a characteristic of a photovoltaic device
Creates electric energy from light
What is a characteristic of a photo conductive device
Resistance is lowered with light
How does an LED differ from a photo diode
Led- emits light/fwd bias
Photodiode- exposed to light/is reverse bias
What is a common use for photovoltaic cells
Solar panel
What are characteristics of a diffuse sensing light sensor
-Emitter and receiver in the same housing
-Operation depends on reflective properties of the target
What are strengths of a diffuse light sensor
-Small object detection
-detects clear glass or plastic
Hole detection
What are characteristics of a retroflective light sensor
Emitter and receiver in same housing
Strengths of a retroflective light sensor
-Immune to colour or texture
-hole detection
-surface doesn’t have to be perfectly perpendicular
What are characteristics of a seperate light sensor
Emitter and receiver are in seperate housing
What is the strength of a seperate light sensor
Longest sensing distance
