Automated Controls Flashcards by Benjamin Dunlop

What does IoT stand for

Internet of things

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What is an advantage and disadvantage of an automated system

-Ongoing labour is reduced
-initial labour is usually higher

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What are three characteristics of an open loop system

-requires an operator
-not self correcting
-not feedback

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What are three characteristics of a closed loop system

-not operator
-is self correcting
-has feedback

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Advantages of an open loop system

-low initial cost
-easy to install
-simple to troubleshoot

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Disadvantages of an open loop system

-ongoing labour
-error can occur (human)

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Advantages of a closed loop system

-self correcting
-reduced ongoing labour
-reduced error
-higher performance

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Disadvantages of a closed loop system

-high initial cost
-expensive to install
-more complex to troubleshoot

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Briefly describe what the error signal does

Sees the difference between the setpoint and the sensor signals

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What are the 5 most common process variables

-temp
-level
-pressure
-rpm
-light

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What are the two modes within a closed loop and an open loop

-dis-continuous
-continuos

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Describe a characteristic of discontinuous control

Discontinuous control uses actuators which are either on or off
-digital sensor

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What is a characteristic of a continuous control

The actuator is variable and is proportional to the difference of the sensor and setpoint

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Is continuous control analog or binary?

Analog

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Is discontinuous control analog or binary

Binary

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The process variables of a continuous control is dependent upon?

-resolution of the sensors
-performance of the actuators
Compliance of the process variable

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What does P & ID stand for

Piping and instrumentation drawings

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What does PID stand for

Proportional integral derivative

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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

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Describe what a transducer does

Converts one form of energy to another

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What are most sensors

They are transducers

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What do active transducers do

Generate output without external power

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What do passive transducers do

Do not generate an output
Only physically or electrically change
External power supply required

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Sensors often have two components what are they

Primary element
Secondary element

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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