1. by:Celestino A. Cole, Jr.2/5/2012 cole.celestino/motor control fundamentals 1

2. OBJECTIVE At the end of the presentation we will know the following: 1. Power circuit and control circuit 2. Ladder diagram and logic equivalent 3. Control components and motor control protection 4. Advance applications.2/5/2012 cole.celestino/motor control fundamentals 2 3. I. CONTROL CIRCUITAND POWERCIRCUIT2/5/2012 cole.celestino/motor control fundamentals 3 4. POWER CIRCUIT AND CONTROL CIRCUITPOWER CIRCUIT- is a circuit used to supply electric energyto the motor.2/5/2012 cole.celestino/motor control fundamentals 4 5. POWER CIRCUIT AND CONTROL CIRCUITCONTROL CIRCUIT- is a circuit used to supply controlcomponents in the motor control circuit. CONTROL CIRCUIT2/5/2012 cole.celestino/motor control fundamentals 5 6. POWER CIRCUIT AND CONTROL CIRCUIT CONTROLCIRCUIT POWER CIRCUIT COMPLETEMOTOR CONTROLCIRCUIT POWER CIRCUIT + CONTROL CIRCUIT= COMPLETE MOTOR CONTROL CIRCUIT2/5/2012 cole.celestino/motor control fundamentals 6 7. II. LADDER DIAGRAM AND LOGICEQUIVALENTS2/5/2012 cole.celestino/motor control fundamentals 7 8. LADDER DIAGRAMLADDER DIAGRAM- is a specialized schematics used todocument industrial logic system.They are called "ladder"diagrams because they resemblea ladder, with two vertical rails(supply power) and as many"rungs" (horizontal lines) asthere are control circuits torepresent.2/5/2012cole.celestino/motor control fundamentals 8 9. LADDER DIAGRAMAdvantages:1. Capable of simplifying complicated motor control circuits compare to schematic diagrams.VS. = 2/5/2012cole.celestino/motor control fundamentals 9 10. LADDER DIAGRAMAdvantages:2. Easy to trace faults.System start/stopFloat control motor starter 2/5/2012cole.celestino/motor control fundamentals10 11. LADDER DIAGRAMAdvantages:3. Easy to translate with logical circuits for advance applications such as inPLC, process control automation, embedded intelligent systems andSCADA. PB1PL = PB1* PB2 PL PB2PB1PLPL = PB1 + PB2PB2 2/5/2012cole.celestino/motor control fundamentals 11 12. LADDER DIAGRAMHOW TO CREATE A LADDER DIAGRAM+24VDC 0VVERTICAL RAILS COMPONENTSRUNG2/5/2012 cole.celestino/motor control fundamentals 12 13. RULES IN LADDER DIAGRAM Input OutputAuxiliary contact Input determines the initial state of the system. Output functions either ON/OFF depending on the logic of the input combination. Auxiliary contact is dependent to the state of the device that they are into. It changes its initial state from close to open or vice versa once the device is activatedRUN SIMULATION2/5/2012 cole.celestino/motor control fundamentals13 14. III. MOTOR CONTROLCOMPONENTS ANDPROTECTION2/5/2012 cole.celestino/motor control fundamentals 14 15. MOTOR CONTROL COMPONENTSSWITCH Switch is an electrical device that can break and connect an electrical circuit, as well as interrupting the flow of current or divert it from one conductor to the other. Types of switches typically used in motor control applications: 1. Pushbutton switch 2. Limit switch 3. Selector switch 4. Footswitch 5. Toggle switch2/5/2012 cole.celestino/motor control fundamentals15 16. MOTOR CONTROL COMPONENTSMAGNETIC CONTACTOR main contacts Supply terminals AuxiliaryA magnetic contactor is an contact(s)electrically controlled switch usedfor switching a power circuit. It hasmain contacts used for powercircuit and auxiliary contact usedfor control circuit.2/5/2012 cole.celestino/motor control fundamentals 16 17. MAGNETIC CONTACTORControl circuit RUN SIMULATION Power circuit2/5/2012cole.celestino/motor control fundamentals 17 18. CONTROL RELAY A relay is an electrically operated switch. The principle of operation is similar to that of the contactor but differs in application. While contactor is used to control motors. Control relay on the other hand is used to control the operation of other control components particularly the magnetic contactor.2/5/2012 cole.celestino/motor control fundamentals 18 19. CONTROL RELAY Magnetic contactorB CIn PLC application thevoltage that activates V1and V2 is coming from thePLC. The circuit istransitioned from PLC to When terminals V1 and V2 are magnetic contactor via energized the initial state of eachcontrol relays for safetypurposes. Although contacts will change accordingly.possible, it is not From close to open and vice versa. technically practical towire directly magneticcontactor to PLC since alarge feedback AC currentfrom the contactor circuitmay harm the PLC unit.2/5/2012cole.celestino/motor control fundamentals 19 20. TIMER Relay timer contains an auxiliary contacts NO and NC that can be integrated into motor control circuits. The initial state of its contact will change when activated after pre-determined value. The timer unit can be set into seconds or minutes depending on the application requirements. For longer and iterative tasks, real time timers are available. RUN SIMULATION2/5/2012cole.celestino/motor control fundamentals 20 21. THERMAL OVERLOAD RELAYLine terminals Thermal overload relay is an electrical componentreset used in motor controlSet value dial applicationswhich provide protection for motor against excessive current. Auxiliary contact(s)2/5/2012 cole.celestino/motor control fundamentals 21 22. THERMAL OVERLOAD RELAY Principles of operation: This component has a bimetal stripAs current rises, heat also rises. that is made of two dissimilarThe hotter the bimetal strip metals bonded together. The two becomes, the more it bends. In an metals have different thermal overload condition, the heat expansion characteristics, so the generated from the heater will bimetal strip bends at a given rate cause the bimetal strip to bend when heated.until the mechanism is tripped, stopping the motor.2/5/2012cole.celestino/motor control fundamentals 22 23. THERMAL OVERLOAD RELAY Typical set-up of contactor and overload relay2/5/2012 cole.celestino/motor control fundamentals23 24. THERMAL OVERLOAD RELAY Characteristics: 1. Allow harmless temporary overloads (such as motor starting) without disrupting the circuit. 2. Trip and open a circuit if current is high enough to cause motor damage over a period of time. 3. Can be reset once the overload is removed.2/5/2012cole.celestino/motor control fundamentals24 25. ELECTRONIC OVERCURRENT RELAY (EOCR) Electronic overcurrent relay is used to protect the motor against overload. Unlike thermal overload Typical installation diagram for EOCR relay this component uses current to trigger once there is overload.2/5/2012cole.celestino/motor control fundamentals25 26. OVER/ UNDER VOLTAGE RELAYThis component protects themotor against over voltageand under voltage situation.Typical installation diagram forover/under voltage protection2/5/2012 cole.celestino/motor control fundamentals 26 27. OVER/ UNDER VOLTAGE RELAY OPERATIONMotor contactor11 122122 11 14 Over-voltage alarm 21 24 Under-voltage alarm2/5/2012 cole.celestino/motor control fundamentals27 28. PHASE LOSS/ PHASE SEQUENCE RELAYIn 3-phase system, phase lossIs the event when one or twophases is/are disconnected inthe main supply. Phase sequenceon the other hand is when twoof the phases are interchangedresulting to a reverse rotation ofa 3-phase motor.Phase control relays monitor: Phase loss is mandatory Phase sequenceprotection to every motor Loss of one or more phasesoperation. Phase sequence is for Unbalance level selective purposes only such aspumps that reversing the motordirection may cause seriousdamage to the equipment.2/5/2012cole.celestino/motor control fundamentals28 29. PHASE LOSS/ PHASE SEQUENCEWIRING DIAGRAMMotor contactor PL/PS NC contacts PHASE PROTECTION RELAY2/5/2012 cole.celestino/motor control fundamentals 29 30. TRANSMITTER, TRANSDUCER AND SENSOR IN MOTOR CONTROL Transmitter, transducer and sensor sometimes used interchangeably inindustrial applications. It may simply called sensor, detector or switch. Thisdevices can be integrated in motor control systems to facilitate the function ofthe motor in any industrial processes. Depending upon the nature of requirements and device specification thesecomponents can be installed individually, composite or can be installedwith the aid of the other. Commonly integrated in motor control applications are: 1.Temperature controller 2.Pressure transmitter 3.Humidity sensor 4.Gas leak detector 5.Proximity switch 6.Light sensor2/5/2012cole.celestino/motor control fundamentals30 31. WORKING WITH TRANSMITTERS IN MOTOR CONTROL Example of composite system where two separate devices are integratedtogether to perform the desired function. Example: The specs indicate that the controller needs PT100 type thermocouple to operate Example of stand-alone unit.Example: A photo sensor that is commonly used in street lightingsthat can also be used in motor control applications can be installedstand alone.2/5/2012cole.celestino/motor control fundamentals31 32. TRANSMITTERS AND SENSORSIN MOTOR CONTROL Input in its raw form suchas:- Temperature INPUT The controller will- PressureDiscrete output- Light process theOUTPUT- Color such as NO and NC- Moisturedetected signal contactsINPUT and transformed it These inputs are detectedby the sensor and to beinto an output inAnalogue outputcarried out as electrical the form ofOUTPUT such as 4-20 mAsignals:discrete or and 0-10 voltsINPUT- Temperature sensor analogue.- Pressure transmitter- Gas leak detector- Smoke sensorTheoretical background2/5/2012 cole.celestino/motor control fundamentals32 33. TRANSMITTER AND SENSORS IN MOTOR CONTROL APPLICATIONS w/ analog output PLATINUM RESISTANCETHERMOMETERS FOR REMOTE SENSING= w/ auxiliary contacts TEMPERATURE CONTROLLER WITH ANALOG AND DIGITAL OUTPUT2/5/2012 cole.celestino/motor control fundamentals33 34. TRANSMITTER AND SENSORS IN MOTOR CONTROL APPLICATIONS In motor control discrete output are characterized by normally close and normally open contacts. This contact output are to be integrated to control circuits.15 162/5/2012cole.celestino/motor control fundamentals34 35. TRANSMITTER AND SENSORS IN MOTOR CONTROL APPLICATIONS In industrial control systems analog signals are commonly characterized by 4-20 mAor 0-10 volts. This is used when the application does not require fully activated ordeactivated systems. This output signal is then integrated into other devices thatdirectly controls the motor such as Variable Frequency Drive.