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3442 Industrial Instruments 2 Chapter 7 Final Control

Princess Sumaya Univ. Electronic Engineering Dept. 3442 Industrial Instruments 2 Chapter 7 Final Control. Dr. Bassam Kahhaleh. 7: Final Control. Objective

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3442 Industrial Instruments 2 Chapter 7 Final Control

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  1. Princess Sumaya Univ.Electronic Engineering Dept. 3442Industrial Instruments 2Chapter 7Final Control Dr. Bassam Kahhaleh

  2. 3442 - Industrial Instruments 2 7: Final Control Objective The function of the final control element is to translate low-energy control signals into a level of action commensurate with the process under control.

  3. 3442 - Industrial Instruments 2 7: Final Control Operation • Block Diagram Signal Conversions Actuator Control Signal Final Control Element Process

  4. 3442 - Industrial Instruments 2 7: Final Control Operation • Block Diagram Signal Conversions Actuator Control Signal The devices that perform such signal conversions are often called transducers because they convert control signals from one form to another, such as current to pressure, current to voltage … etc. Final Control Element Process

  5. 3442 - Industrial Instruments 2 7: Final Control Operation • Block Diagram Signal Conversions Actuator Control Signal Final Control Element Theactuator is a translation of the (converted) control signal into action on the control element. Process

  6. 3442 - Industrial Instruments 2 7: Final Control Operation • Block Diagram Signal Conversions Actuator Control Signal Final Control Element Thecontrol element is operated (run) by the actuator. Process

  7. 3442 - Industrial Instruments 2 7: Final Control Operation • Block Diagram Signal Conversions Actuator Control Signal Final Control Element Theprocess is operation (objective) under control. Process

  8. 3442 - Industrial Instruments 2 7: Final Control Operation Example: Baking of Crackers

  9. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Relays • Mechanical • Solid-State • Amplifiers • Transistor • Op-amp

  10. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Relays • Mechanical

  11. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Relays • Mechanical

  12. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Relays • Mechanical

  13. V (Volts) 10 5 I (mA) 4 20 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Op-amp Example: Convert a “4 – 20” mA control signal to a “5 – 10” V signal. Solution: Vin = Rin * Iin Vout = K Vin + VB

  14. Vout (V) 10 5 Vin (V) 0.4 2 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Op-amp Solution: Vin = Rin * Iin Let Rin = 100 Ω

  15. Vout (V) 10 5 Vin (V) 0.4 2 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Op-amp Solution: Vout = K Vin + VB 5 = K * 0.4 + VB 10 = K * 2 + VB K = 3.125 VB = 3.75 Vout = 3.125 Vin + 3.75 Vout = 3.125 (Vin + 1.2)

  16. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Analog Electrical Signals • Op-amp Solution: Vout = 3.125 (Vin + 1.2)

  17. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Digital Electrical Signals • Op-amp • DAC • Direct Action Example: A 4-bit digital word is intended to control the setting of a 2-Ω DC resistive heater. Heat output varies as a 0 – 24 V input to the heater. Using a 10–V DAC followed by an amplifier and a unity gain high-current amplifier, calculate: a) the settings from minimum to maximum heat dissipation, and b) how the power varies with LSB changes.

  18. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Digital Electrical Signals • DAC Solution: DAC 10–V reference  24 = 16 Therefore: 1111  (15/16) * 10 = 9.375 V . . 0000  0 V Amplifier gain = 24 / 9.375 = 2.56 Incremental step = [(1/16) * 10 ] * 2.56 = 1.6 V ΔV = (1/16) * 10 V

  19. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Digital Electrical Signals • DAC Power (W) Solution: ΔP (from 0000 to 0001) = (1.6 V)2 / 2 Ω = 1.28 W ΔP (from 1110 to 1111) = (24)2 – (22.4)2 / 2 = 37.12 W Control Ward

  20. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Pneumatic Signals • Pressure signal travels down the pipe at a speed in the range of the speed of sound.

  21. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Pneumatic Signals • Pressure signal travels down the pipe at a speed in the range of the speed of sound. • Amplifier (booster or relay)

  22. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Pneumatic Signals • Pressure signal travels down the pipe at a speed in the range of the speed of sound. • Amplifier (booster or relay) • Nozzle/Flapper system

  23. 3442 - Industrial Instruments 2 7: Final Control Signal Conversions • Pneumatic Signals • Pressure signal travels down the pipe at a speed in the range of the speed of sound. • Amplifier (booster or relay) • Nozzle/Flapper system • Current-to-Pressure converters

  24. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics • Silicon-Controlled Rectifier (SCR) • Maximum forward current • Peak reverse voltage • Trigger voltage • Trigger current • Holding current

  25. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics • SCR Operation: Half-wave

  26. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics • SCR Operation: Full-wave

  27. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics • SCR Operation: Full-wave (with digital control)

  28. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics SCR Example An SCR with a 4.0–V trigger is used as a light–dimmer control. What resistance, R, should be used to provide approximately 10% to 90% ON time?

  29. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics SCR Example

  30. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics SCR Example VC(t) = VO(1 – e-t/RC) 4.0 = 10 (1 – e-t/RC) t = 0.511 RC T half a cycle = 10 ms 10%  1 ms 90%  9 ms With C = 0.12 μF Rmin = 16.3 KΩ Rmax = 147 KΩ

  31. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics • TRIAC • DIAC

  32. 3442 - Industrial Instruments 2 7: Final Control Industrial Electronics • TRIAC

  33. 3442 - Industrial Instruments 2 7: Final Control TRIAC Example An DIAC with a 28–V breakdown voltage is used in the light–dimmer control. What resistance, R, should be used to provide approximately 10% to 90% ON time? Industrial Electronics

  34. 3442 - Industrial Instruments 2 7: Final Control TRIAC Example When does VAC reach 28 Volts so that it becomes possible to trigger the TRIAC? Industrial Electronics 28 = 310 sin(314 t) t = 0.288 ms ≈ 2.9% of the period And for 40 Volts: 40 = 310 sin(314 t) t = 0.412 ms ≈ 4.1% of the period

  35. 3442 - Industrial Instruments 2 7: Final Control TRIAC Example Industrial Electronics • 28 = 40 [ 1 – e – t / RC ] • t = 1.2 RC • If t = 1 ms: Rmin = 6.9 KΩ • If t = 9 ms: Rmax = 62.5 KΩ

  36. 3442 - Industrial Instruments 2 7: Final Control Actuators • Electrical Actuators • Solenoid

  37. 3442 - Industrial Instruments 2 7: Final Control Actuators • Electrical Actuators • Solenoid • DC Motor • AC Motor

  38. 3442 - Industrial Instruments 2 7: Final Control Actuators • Electrical Actuators • Solenoid • DC Motor • AC Motor • Stepping Motor

  39. 3442 - Industrial Instruments 2 7: Final Control Actuators • Electrical Actuators • Solenoid • DC Motor • AC Motor • Stepping Motor • Pneumatic Actuators

  40. 3442 - Industrial Instruments 2 7: Final Control Actuators • Electrical Actuators • Solenoid • DC Motor • AC Motor • Stepping Motor • Pneumatic Actuators • Hydraulic Actuators

  41. 3442 - Industrial Instruments 2 7: Final Control Control Elements • Mechanical • Solid-Material Hopper Valves

  42. 3442 - Industrial Instruments 2 7: Final Control Control Elements • Mechanical • Paper Thickness

  43. 3442 - Industrial Instruments 2 7: Final Control Control Elements • Electrical • Motor Speed Control

  44. 3442 - Industrial Instruments 2 7: Final Control Control Elements • Electrical • Temperature Control

  45. 3442 - Industrial Instruments 2 7: Final Control Control Elements • Fluid Valves

  46. 3442 - Industrial Instruments 2 7: Final Control End of Chapter 7

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