Series 280: Process Control Systems
Course 282: How Control Loops Operate
Covers definition of control loop terms and characteristics. Includes specific examples of operation of control loops of many kinds. Discusses proportional, integral, and derivative modes in detail. Describes advanced control methods by means of four strategies with specific examples. Examines the effects of loop dynamics on system stability.
TPC Training Systems is authorized by IACET to offer 0.5 CEUs for this program.
Lesson 1 - Fundamentals of Control Loops
Topics:
Definitions; Process sensors; Sensor characteristics; Controllers; Recorders; Signal conditioners; Final control elements
Learning Objectives:
- Explain the difference between an open loop and a closed loop.
- Define error, feedback, disturbance, and feedforward control.
- List several kinds of process sensors and describe the operation of each.
- Explain how accuracy, resolution, sensitivity, linearity, and step response affect sensor operation.
- Describe the functions of process controllers, recorders, signal conditioners, and final control elements.
- Explain the basic operation of a typical control loop.
Lesson 2 - Control Loop Characteristics
Topics:
Two-position and floating control; Proportional, integral, derivative, and PID mode; Supervisory control; DDC; DCS
Learning Objectives:
- Describe the difference between continuous and discontinuous control modes and give an example of each.
- Describe the action of the various continuous control modes.
- Define proportional band, reset time, and rate time.
- Discuss the advantages of each of the combination control modes.
- Name several advantages of digital controllers.
- Discuss the differences between supervisory control, direct digital control, and distributed control systems.
Lesson 3 - Advanced Control Methods
Topics:
Cascade and ratio control system; Feedforward control; Ratio control in a secondary loop; Multivariable control systems
Learning Objectives:
- Describe how a cascade control system works.
- Identify the primary and secondary variables in a cascade loop.
- Compare feedforward and feedback control.
- Identify dependent and independent variables in ratio control.
- Explain the advantage of having a secondary control loop in ratio control.
- Describe how a multivariable control system works and define interaction.
Lesson 4 - Loop Dynamics
Topics:
Effects of process time lag; Dead time compensation; System stability; Transient response; Gain; Phase shift
Learning Objectives:
- Describe two kinds of process time lags and give an example of each.
- Discuss the effects of capacitance and resistance on loop dynamics.
- State the three main objectives of a well-designed process control system.
- Describe how PI, PD, and PID controllers are adjusted to achieve optimum response.
- Discuss the effects of system gain and phase shift on system stability.
Lesson 5 - Loop Protection
Topics:
Explosion-proof enclosures; Intrinsically safe instrument systems; Fail-safe mechanisms; Hard and soft constraints; Alarms
Learning Objectives:
- Discuss the classification of hazardous locations as identified in the NEC Handbook.
- Define volatility and flash point, and explain the purpose of a purged enclosure.
- Describe two kinds of explosion-proof enclosures.
- Discuss ways of making a system intrinsically safe.
- Describe examples of fail-safe mechanisms, and differentiate between hard and soft constraints.
- Compare latching and nonlatching alarm systems, and explain the function of annunciators.
- Discuss the purpose and operation of interlocked and sequential control.
