What is an On-Off Controller?On-Off Controller DefinitionAn on-off controller is defined as a control system that fully opens or closes the control element when the process variable crosses a preset level.Working PrincipleThe on-off controller works by fully opening or closing the output value, causing the process variable to change direction and cycle continuously.Example of ApplicationA typical example is the cooling fan control in transformers, which activates based on temperature levels.Actu

What is Control Engineering?Control Engineering DefinedControl engineering is the field of engineering that focuses on designing and optimizing systems to function in a desired, controlled manner using principles of control theory.Classical vs. ModernClassical control engineering uses transformed equations to analyze Single Input Single Output systems, while modern control tackles complex systems with state-space and vector methods.Historical SignificanceThe history of control engineering showca

Simple emergency lighting circuit

What is Nyquist Criteria ?Nyquist Stability Criterion DefinitionThe Nyquist stability criterion is defined as a graphical technique used in control engineering to determine the stability of a dynamical system.Application of Nyquist CriterionIt applies to open-loop systems and can handle transfer functions with singularities, unlike Bode plots.Criterion FormulaZ = number of roots of 1+G(s)H(s) in right-hand side (RHS) of s-plane (It is also called zeros of characteristics equation)N = number of e

Double supply lighting circuit

What is a SCADA System?SCADA DefinitionSCADA is defined as Supervisory Control and Data Acquisition, a system used for high-level process control and data management.Component Master Terminal Unit (MTU) Remote Terminal Unit (RTU) Communication Network (defined by its network topology)Functions To monitor and gather data in real-time To interact with field devices and control stations via Human Machine Interface (HMI), To record systems events into a log file To control the manufacturing processe

What is Steady State Error?Steady State Error DefinedSteady state error is the discrepancy between a control system’s desired and actual output values once the output has stabilized.Influence of Input TypesThe size of the steady state error varies with different types of inputs—zero for step inputs, a constant for ramp inputs, and infinite for parabolic inputs.System StabilityUnlike steady state error, the stability of a control system does not depend on the type of input but on the system’s tra

Fire alarm circuit

What is a Transfer Function?DC Gain DefinitionDC gain is the ratio of the steady-state output to the steady-state input of a control system when given a step input.Transfer FunctionA transfer function represents the relationship between a control system’s input and output using the Laplace transform.Final Value TheoremThe final value theorem helps find the DC gain by evaluating the transfer function at zero for continuous systems.Continuous vs. Discrete SystemsDC gain calculations differ between

What is Rise Time?Rise Time DefinitionRise time is defined as the duration it takes for a signal to increase from 10% to 90% of its steady value, indicating how quickly a signal changes.Rise Time FormulaThe rise time formula varies based on the system type.Calculation MethodTo calculate rise time, use the transfer function to determine time constants and calculate the times when the signal reaches 10% and 90% of its final value.Practical MeasurementRise time is typically measured using an oscill