Author: John Mulindi
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Megohmmeter: Function & Operation
The megohmmeter or megger is a portable deflection instrument widely used to check the insulation resistance of electrical cables and equipment. In other words, a megohmmeter can be described as a high resistance measurement instrument. The instrument has a constant high-voltage source, normally produced by a hand-cranked generator. The voltage may range anywhere between 100…
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Microwave Passive Components: Types & Functions
The part of the electromagnetic spectrum referred to as the microwave region loosely includes 1-300 GHz for practical purposes. These microwave bands are especially advantageous for transmission services such as satellite transmission, telephone transmission, broadcasting of commercial radio & television, and oil platform transmission. Some of the key advantages of microwaves are that the energy…
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Sources of Coherent Interference/Noise in Instrumentation Systems
Introduction The knowledge of how to design low noise instrumentation systems is an essential skill that any practicing instrumentation engineer should strive to learn because noise and interference affects any measurement system in one way or the other and this in turn affects the precision of measurements and the detectability of the quantity of measurement.…
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What is Optimal Control?
Optimal control is whereby the requirements are formulated as either the minimization of a cost index or the maximization of a performance index of an operational control system. Optimal control is utilized in a number of disciplines such as aircraft and spacecraft, satellites and aerospace, communications engineering, robots and robotics, electric drives, power systems, computer…
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Fiber Optic Temperature Sensors: Principle of Operation & Applications
As the name suggests these sensors employs fiber optics technology to function. A fiber optic sensor generally guides light to and from a measurement zone where the light is modulated by the measurand of interest and returned along the same or a different optical fiber to a detector at which the optical signal is interpreted.…
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Non-Destructive Testing (NDT) Instrumentation
The increasing requirement to demonstrate the integrity and reliability of engineering materials, products and plant has contributed immensely to the development of non-destructive testing instrumentation. Efficient materials manufacture, the assurance of product quality and re-assurance of plant at regular intervals during use represent the need for non-destructive testing (NDT). The failure in engineering components generally…
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Standards Used in Measurements & Their Classifications
For anyone performing a measurement using a particular instrument, it usually matters to know whether the instrument is calibrated or not. Calibration is required, along with precision, to enable accurate measurements to be made. Calibration means observing the instrument’s performance when measuring a standard of some kind. A standard is a physical representation of the…
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Radar Level Transmitters: Operating Principle & Applications
Radar level transmitter basically employs electromagnetic waves to determine the fluid level in a tank. It converts level information into a 4-20 mA signal and transmits it to the controller; this signal may then be used in a measurement and control loop to control a process. The level is also displayed by an inbuilt display…
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Pneumatic Signal Transmission System
Signal transmission in process instrumentation and control systems is largely done via electrical transmission but there are a few areas where pneumatic transmission of signals is vital especially where electrical signals or sparks can ignite combustible materials for example in petroleum refineries. In pneumatic transmission systems, the measured quantity (pressure, level, temperature, and so…
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How Redundancy is Achieved in Process Plants
In similar way to electronic systems, redundancy is extensively employed technique for enhancing the reliability of many industrial plants and processes. Because many process plants units such as pumps, valves and compressors involve moving parts, they are prone to wear and therefore require periodic inspection and maintenance. Where the plant is required to operate continuously,…