PLC Control and Sensor Integration for Industrial Automation
Explore the principles of programming logic controllers, configuring input/output devices, and motor controls in Chapter 4 of a PLC system. Learn to manage output control, adjust motor speed, and monitor parameters like temperature, pressure, and humidity using pushbuttons, switches, and sensors.
PLC Control and Sensor Integration for Industrial Automation
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Presentation Transcript
Programming Logic Controllers Input/Output Devices & Motor Controls - Chapter 4
PLC Control • Output control • Turn on/off a circuit • Increase/decrease motor speed or torque • Input parameters • Temperature • Pressure • Humidity • Time
Pushbuttons and Switches • Discrete input devices • either on or off • Connected to PLC inputs • When ON they place a positive voltage • When OFF they apply zero voltage to the port • (NO) Normally open – on until switched off • (NC) Normally closed – off until switched on
Pushbuttons • Momentary • Must hold open/closed • Return to normal position when released • Locked-position • Latch until state changed again physically
Switches • Manual • Require human intervention • Automatic • Mechanical or electrical • Thermostat • Limit switch
Switches cont’d • Temperature Switch • Pressure Switch • Liquid level Switch • Flow Switch • Float Switch • Foot Switch • Proximity Switch • Led + phototransistor
Sensors • Digital – high low voltage • Analog – varying voltage levels • Proximity Sensors • Inductive Sensor – detects current induced from magnetic fields to detect metal • Capacitive Sensor – measures change in sensors dielectric caused by nearby objects • Optical sensors • Emitter + detector • Visible, ultraviolet, infrared, or laser • Reflection varies with object type
Hall Effect Sensor • Reed switch • Switched by magnetic fields pull or push • Solid state • Resist vibration • Relay used wire coil to generate magnetic field • Reed switch used permanent magnate
Ultrasonic Sensor • Above 16kHz sound ping (like submarine) • Time for reflected sound to return proportional to object’s distance • Accurate over short distances and cheap • Electrostatic up to 50kHz • Capacitive • Longer range but sensitive to environment • Piezoelectric up to 1MHz • Rugged • Crystal lattice produces voltage
RADAR Sensors • Radio Detection and Ranging • Detect metal objects • Not used in factories
Cameras & Object Recognition Software • Can identify defects • Detecting which parts • Quality assurance • Getting better
Indicators • Pilot lights • Red yellow green for states/conditions • Ammeters & Voltmeters • Looking for undervoltageor overcurrent conditions
Relays & Contactors • Relay • like a reed switch but with a coil • energized (magnetized) • de-energized (demagnetized) • Power relay (contactor) or control relay (relay) • Contactor • Power relay • Uses a small amount of voltage to control a large amount • Solid state relays • No moving parts to wear out • perform well in harsh environments
Solenoids • Convert electrical energy into mechanical motion • Movable plunger at core with spring • When energized plunger is pulled • When de-energized spring reverses action
Motor Control • Motor Starters • Constant speed motors (on/off) • Contactors and Overload protection overload relays • Temperature or thermal overload relay - common • Magnetic overload relay - faster but $$$ • Motor Drives • Soft start stand still to operating speed • Plugging when motor reverses direction
Electrical Symbols http://www.techtransfer.com/resources/wiki/entry/1829/#Contacts
Electrical Symbols http://www.wadeinstruments.com/ez_schematics/description.htm
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