Motor Control


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This slideshow is a presentation for IIEE-Bahrain technical seminar (AUTOMATION MOTOR CONTROL SYSTEMS) that was conducted on December 2, 2011 at Kingdom of Bahrain. Seminar was conducted by Celestino Cole

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Motor Control

  2. 2. 1. Definition of motor controllers.2. Different types of motor controllers.3. How control circuit interacts with different components to met specific requirements.4. The use of motor control for energy savings. cole.c/motor_control 2/5/2012 2
  3. 3. ELECTRIC MOTOR- is an electrical machine that converts electrical energy tomechanical energy in order to produce work.  Modern civilization is incomplete without electric motors !!! cole.c/motor_control 2/5/2012 3
  4. 4. A motor controller is a device or group ofdevices that serves to govern in somepredetermined manner the performance of anelectric motor.A motor controller includes a manual orautomatic means for starting and stoppingthe motor, selecting forward or reverserotation, selecting and regulating the speed,regulating or limiting the torque, andprotecting against overloads and faults. cole.c/motor_control 2/5/2012 4
  6. 6. Full voltage starter is the most common type ofmotor starter where the motor is connecteddirectly across the line. When started this way the starting current will reach as high as 600% of its full load current. This method of starting is used for motors 10 HP and below. cole.c/motor_control 2/5/2012 6
  7. 7. Commonly known as across the line method of starting. This type of starter is used when controlling motor in one direction. * When the start button is pressed the contactor is activated closing the main contact M and causes the motor to run. * The auxiliary contact M that is connected in parallel with the “start” pushbutton will hold the whole rung remain activated whenever the pushbutton will return into its original position after pressing. RUN SIMULATIONcole.c/motor_control 2/5/2012 7
  8. 8. cole.c/motor_control 2/5/2012 8
  9. 9.  Depending upon the requirements every circuit may vary depending upon the application requirements. For example: The NC auxiliary contact of the pressure switch can be connected in series with the standard DOL starter in order to automatically off the motor once the set value for pressure is reach. cole.c/motor_control 2/5/2012 9
  10. 10. Commonly known as forward-reverse method of starting. This type of starter is used when controlling motor in two directions. * When the forward F contactor is activated the motor will put into forward direction. * The key for reversing the direction of the motor is that the lines that supplies the other contactor (R) L1and L3 is interchanged. * The 2 normally closed contacts that are connected in series in forward and reverse rung respectively are called electrical interlocking. This is to prevent simultaneous activation of the 2 rungs that might cause serious damage to theRUN SIMULATION equipment if happens. cole.c/motor_control 2/5/2012 10
  11. 11. cole.c/motor_control 2/5/2012 11
  12. 12. LS LS The NC contact from the limit switch can be connected in series with the UP branch of the reversing circuit to automatically stop the motor once it reach the desired level. Similarly the NC contact from the limit switch can be connected in series with the DOWN branch of the reversing circuit to automatically stop the motor once it reach the desired level. cole.c/motor_control 2/5/2012 12
  13. 13. Reduced voltage starter is a type of motor starter wherein the effect ofthe starting inrush current is suppressed. This can be accomplish bythe used of sequential switching from the initial to the final state. Oncethe motor has come up to some fraction of its full-load speed thestarter switches to full voltage at the motor terminal. Full voltage starting of motors can produce objectionable voltage flicker, mechanical stress to gear boxes or belt drive systems and create pressure surges or water hammer in pumping applications. Starting a motor at reduced voltage can help reduce or overcome these problems. Reduced voltage is typically used for motors 10 HP or more. cole.c/motor_control 2/5/2012 13
  14. 14. Wye-Delta is an electromechanical way of reducing the voltageapplied (58%) during starting. This can be accomplish byconnecting the motor at Y first during starting (3-5sec) andchanging it to DELTA thereafter. In 3-phase system: cole.c/motor_control 2/5/2012 14
  15. 15. RUN SIMULATION cole.c/motor_control 2/5/2012 15
  16. 16. T6CIRCUIT OPERATION INWYE-DELTA STARTING cole.c/motor_control 2/5/2012 16
  17. 17. float NC auxiliary contact for float control relay can be installed in series with the main contactor to automatically control the pump operation. The pushbuttons are replaced with selector switch since the latched circuit cannot be automatically activated once deactivated. cole.c/motor_control 2/5/2012 17
  18. 18. Once the start button is pressed the contacts from S and Y contactor will be close, thus reducing the starting current at the desired level. After 3-5 seconds these contacts will open followed by the closing of contacts from contactor R.cole.c/motor_control 2/5/2012 18
  19. 19. Autotransformer starting method is commonly used in large submersible pumpmotors. Just like wye-delta the effect of starting inrush current is suppressed. BENEFITS: 1. Submersible pumps commonly have 3 leads out, making it unfit for wye-delta starting. 2. If there are 6 leads out submersible pump available then it is economically impractical to use wye-delta since it follows that an additional three conductors are needed to power up the motor. 3. Other applications where the starting voltage is to be reduced lower than 58% then autotransformer can be used since wye-delta starting is fixed at 58%. cole.c/motor_control 2/5/2012 19
  20. 20.  PWS can be accomplished by first energizing the half of the motor coil for at most 3 seconds then followed by the energization of the overall coil. Unlike the wye-delta starting that is used for accelerating the motor or provide reduced torque, PWS on the other hand mainly used to minimized voltage drop that keeps the nearby lights free from flickering. RUN SIMULATION cole.c/motor_control 2/5/2012 20
  21. 21. Soft starter is a solid state device used with AC electric motorsto temporarily reduce the load and torque of the motor duringstartup. This reduces the mechanical stress on the motor andshaft, as well as the electrodynamic stresses on the attachedpower cables and electrical distribution network, extending thelifespan of the system. cole.c/motor_control 2/5/2012 21
  22. 22. TYPICAL POWER CIRCUIT cole.c/motor_control 2/5/2012 22
  23. 23.  Auxiliary SCR output contact 13-14 is used for controlling the start/stop function directly wired from the control circuit to the soft starter.  Auxiliary SCR output contact 23-24 is activated when the ramp up time has elapsed causing theTYPICAL POWER CIRCUIT by-pass contactor to be activated. cole.c/motor_control 2/5/2012 23
  24. 24. DIRECT ON LINE WYE- DELTA SOFT STARTER cole.c/motor_control 2/5/2012 24
  25. 25. cole.c/motor_control 2/5/2012 25
  26. 26. VFD system cole.c/motor_control 2/5/2012 26
  27. 27. VFD can be controlled bymany ways such as:• Button or attached HMI• Discrete input from PLC or other remote controlled relay• Potentiometer for remote control operation • PID signal from transmitters and transducers• Computer ports thru RS-485 cole.c/motor_control 2/5/2012 27
  28. 28. VFD is controlled manually by keypad or attached HMI. cole.c/motor_control 2/5/2012 28
  29. 29. CAN SEAMER TIN COIL CUTTING LINE cole.c/motor_control 2/5/2012 29
  30. 30. For remote control manual operation: For automated operation:A separate remote control unit using A remote control unit and feedbacktoggle switch, pushbutton and control using transmitters andpotentiometer can be installed to control transducers forming close loop systemthe operation of the VFD. is installed to control the operation of the VFD. cole.c/motor_control 2/5/2012 30
  31. 31.  Discrete output from PLC can be connected directly to VFD. cole.c/motor_control 2/5/2012 31
  32. 32. BOILER CONTROL ROOM DEVICE LOCATION cole.c/motor_control 2/5/2012 32
  33. 33. --- 4-20 mA or 0-10 VDCAUTOMATING VFD SYSTEM CAN BE USED FOR ENERGY SAVING PURPOSES cole.c/motor_control 2/5/2012 33
  34. 34. Temperature HMI sensor motor Temperature PLC controller -analogue signal feedback: 4-20 mA or 0-10 VDC The VFD can be activated manually thru HMI or from PLC if the motor operation is dependent on the other parts of the industrial processes. The function of the analogue feedback signal is to keep the speed of the motor at the set value. cole.c/motor_control 2/5/2012 34
  35. 35.  In air-blast freezer where the fan are used to induced cool air to the products.  Once the cool air are uniformly distributed all throughout the products, the temperature will tend to go down until the temperature will reach into the saturated level (e.g. -35 degree C ).  When the temperature will go beyond its required value, it is already useless as far as the requirement is concern.  The fan that are continuously running at full speed once the temperature requirement is met manifests waste of energy.Solution: The temperature sensor will detect that the temperature level. The sensor will send feedback to the VFD thru temperature controller. The VFD now will regulate the speed of the motor so as to met the required temperature. cole.c/motor_control 2/5/2012 35
  36. 36.  In grain dryer the fan are used to induced hot air to the products.  The size of the drying bin is fixed and the fan is designed for that size.  Sometime the volume of the production is relatively lower than the drying capacity.  If the fan is operated at full speed it could result into substandard products.  The conventional solution for this problem is the installation of valve in the drying bin that would served as a passage to the excess hot air.  The evacuated hot air manifests waste of energy.Solution: The temperature sensor will detect that the temperature level. The sensor will send feedback to the VFD thru temperature controller. The VFD now will regulate the speed of the motor so as to met the required temperature. cole.c/motor_control 2/5/2012 36
  37. 37. AFFINITY LAW OF REMEMBER THAT: CENTRIFUGAL LOADS: Nsyn = (120 x f ) / P P2/P1 = (f2/f1)3 P2= (f2/f1)3 X P1 f = (P x Nsyn ) / 120 From the formula it is clear that an 80% speed reduction of the motor driving centrifugal loads such as pumps and fans can make 50% reduction of electrical consumption. SAMPLE cole.c/motor_control 2/5/2012 37
  38. 38. THANK YOUVERY MUCH… cole.c/motor_control 2/5/2012 38