Tag: instrumentation
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Digital Multimeter: Principle of Operation and How it is used
A Multimeter or volt-ohm-milliammeter (VOM) is an instrument used to measure current, voltage, and resistance. It can be used for measuring dc as well as ac voltages and currents. The two common types of multimeters include the analog multimeter and the digital multimeter. Analog multimeters employs a moving pointer mechanism that swings a long a…
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Single-Ended vs. Differential Amplifiers
Most often than not, the signal from the sensor in a measurement and control or monitoring system is very small (one millivolt or less) and a key step in signal conditioning is amplification. Therefore, the sensor is often connected to the input terminals of an amplifier. The amplifier in this case can either be single-ended…
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Causes of Ground Loops in Instrumentation & How to Avoid Them
Causes of Ground Loops In Instrumentation We may have situations in instrumentation and control systems, where the sensor and the signal conditioning unit such as an amplifier or current-to-voltage converter are located some distance apart and are connected by a cable. This can lead to several problems that can reduce the accuracy or in extreme…
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Telemetry in Instrumentation Systems
Telemetry can be defined as the science of gathering information at some remote location and transmitting the data to a convenient location to be examined and recorded. Importance of Telemetry Within instrumentation there is usually a requirement for telemetry in order to transmit data or information between two geographical locations. The transmission may be needed…
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How Capacitive Probes are Used to Measure Level
Capacitive probes can be used to measure the depth of liquids and solids. A rod, normally coated with PVC or PTFE, is inserted into the tank and the capacitance measured to the tank wall. The capacitance has two components C1 above the surface and C2 below the surface. As the level rises C1 will decrease…
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PFDs vs. P&IDs
Process Flow Diagrams (PFDs) defines the major elements of the process schematically i.e. the interconnections of process vessels, pipes and flow paths of process fluids. On the other hand, Piping and Instrument Diagrams (P&IDs) shows the layout of all relevant process vessels, pipes and machinery but with instruments superimposed on the diagram showing what gets…
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Process Instrumentation Diagnostics & Communication Interfaces
There are various technologies that are available that help plant automation personnel to obtain diagnostic data which inform the type of maintenance to be undertaken. For example, using Distributed Control System (DCS), PC software tools, or handheld communicators, plant automation professionals can diagnose the health of an instrumentation device while it is in the line.…
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How a Bubbler Device is used for Level Measurement
An often utilized technique of indirectly measuring a liquid level is to measure the hydrostatic pressure at the bottom of the container. The level can then be extrapolated from the pressure and the specific weight of the liquid. This is the principle that a bubbler device operation is based on. Pressure is commonly used as…
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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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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.…