Author: John Mulindi
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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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DC Transmission and Distribution
In most cases, the dc power is obtained from large ac power systems by employing converting mechanisms like synchronous or rotary converters, solid-state converters and motor-generator sets and so forth. The reasons why power generation is done in ac form rather than dc are: How DC Power is Obtained from AC Power A general layout…
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Optothyristors: Features & Principle of Operation
Silicon Controlled Rectifiers (SCRs), Triacs and other solid-state devices used for switching larger voltages and currents ON and OFF are referred to as thyristors. Thyristors control switching in an ON-OFF way, in the same way to a light switch which is different from a transistor that can vary the amount of current in its emitter-collector…
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Zener Diode and Emitter-Follower/Series Voltage Regulators
Almost all electronic devices and circuits need a dc source of power for their operation. While batteries and dry cells can be used as a form of dc power supply, their voltages are usually low and they require frequent replacement; additionally they are costly compared to regular dc power supplies. The domestic ac supply can…
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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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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…