Tag: instrumentation
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RTD 2, 3, 4 Wire Sensor Connections
The resistance temperature devices (RTD) can be connected directly to the controller peripheral amplifiers using 2-wire, 3-wire or 4-wire lead configuration. The wires in all these connections are in shielded cables. The RTD is usually driven from a constant current … Read more
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How to Connect a DP (Differential Pressure) Flow Sensor to a DP Transmitter
The DP Transmitter should be mounted with a manifold block as illustrated in the figure 1(a) below to allow for maintenance. Figure 1(a) connection of a DP flow sensor to a DP transmitter Valves B and C are the isolation … Read more
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Instrumentation Sensors and Transducers – Multiple Choice Questions & Answers (MCQ4)
The Answers have been provided at the end of the Questions: Q1. Which of the following sensors is used to measure displacement? A. Thermistor B. LVDT C. Dall tube D. None of the above Q2. Which of the below … Read more
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How Signal Processing Circuits are protected from high currents & voltages
Protection against high currents and voltages is a very important requirement for signal processing circuits. A high current can be protected against by the incorporation in the input line of a series resistor to limit the amount of current flowing … Read more
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How RS-232, RS-422 and RS-485 Networks are applied in Instrumentation
RS-232 Presently, this standard is known as TIA-232C. These are point-to-point networks with a purpose of connecting only two devices. The signaling is single-ended (unbalanced) which implies that the respective voltage pulses are referenced to a common ground conductor and … Read more
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Basic Features of Foundation Fieldbus (FF)
Foundation fieldbus (FF) and Profibus are the two most universal serial data bus formats that are used for interfacing between the central processor and smart devices in the process control system. The Foundation Fieldbus is mainly used in U.S. while … Read more
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Hazardous Locations Classifications
A hazardous location is defined as a location where fire or explosion hazards exist due to the presence of flammable gases, vapors, or liquids, combustible dusts or ignitable fibers. Fire explosions can occur in a wide range of industrial environments … Read more
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Functional Safety in Instrumentation Systems (SIS, SIF & SIL)
Functional safety is the risk reduction provided by the functions implemented to ensure the safe operations of the process. The IEC 61508 standard covers functional safety of electrical/electronic/programmable electronic safety-related systems. The purpose of IEC 61508 is to use safety … Read more
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4-20 mA Transmitters (2-wire, 3-wire and 4-wire Types)
Background of 4-20 mA Signal Transmission Initially signal transmission was dominated by pneumatics before the advent of 4-20 mA signal standard. The standard was 3-15 psi pneumatic signal where the 3 psi was the ‘live zero’ and 15 psi represented … Read more
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What is a Smart Sensor?
A smart sensor is the integration of a sensor with an analogue to digital converter (ADC), a processor and digital to analogue converter (ADC) for actuator control. A typical application of a smart sensor set up is a temperature control … Read more