Proportional-only Control Theory
Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets the stem position of a control valve. As the liquid level rises, the…
On/off Control Theory
Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I did. I began to explain my job, which was essentially…
Feedback Control Principle
Before we begin our discussion on process control, we must define a few key terms. First, we have what is known as the process: the physical system we wish to…
Flow Meter Installation Guidelines
Flow measurement accuracy of any flow meter becomes compromised is incorrect installation, and pressure-based flow meters are no exception to this rule.
Power Plant Interview Questions & Answers
We prepared an article on Power Plant Interview Questions & Answers which covers basics about power plant operation. Power Plant Interview Questions & Answers 1. Name the four major circuits…
Top 100 Power Plant Engineering Objective Questions & Answers
Top 100 Power Plant Engineering Objective Questions & Answers 1. The commercial sources of energy are (a) solar, wind and biomass (b) fossil fuels, hydropower and nuclear energy (c) wood,…
Why Restriction Orifice is some distance from Blowdown valve ?
Very basic does not imply obvious...i really like this statement. Very often the answer is very fundamental and basic to us, somehow it always does not obvious to us. Restriction…
Calibration and Preventative Maintenance Procedures
Calibration and Preventative Maintenance Calibration: A comparison of two instruments or measuring devices one of which is a standard of known accuracy (traceable to national standards) to detect, correlate, report…
What is a Active Barrier ?
An active barrier uses transformers, optoisolators or relays to provide isolation between the hazardous area and the non-hazardous area. It does not require an intrinsically safe ground connection. Either or…
Zener Diode Barrier Principle
The zener diode barrier works by diverting potentially dangerous energy to ground before it can reach the hazardous area. Zener Diode Barrier Principle The zener diodes limit the fault voltage…
