Instrument Signal Isolation

Signal Isolators, Converters and Interfaces: The "Ins" and "Outs" - Whether you call them signal isolators, signal converters or signal interfaces, these useful process instruments solve important ground loop and signal conversion challenges everyday. Just as important, they are called upon to do a whole lot more. They can be used to share, split, boost, protect, step down, linearize and even digitize process signals. This guide will tell you many of the important ways signal isolators, converters and interfaces can be used, and what to look for when specifying one - from Moore Industries.

What is Signal Isolation? - In most processes there are pieces of electronic measurement and control equipment from many different manufacturers. The signals from these instruments are interconnected to each other and to sensors, transducers and output devices connected in the process loop. In any such measurement and control system there are several electrical interfacing problems that are likely to occur, all of which can be solved by incorporating the appropriate isolation between the signals - from APCS.

Instrument Isolators & Splitters

The following technical papers are from Acromag:

Introduction to the Two-Wire Transmitter and the 4-20mA Current Loop - In two-wire 4-20mA control loops, we use 2-wire transmitters to convert various process signals representing flow, speed, position, level, temperature, pressure, strain, pH, etc., to 4-20mA DC for the purpose of transmitting the signal over some distance with little or no loss of signal. This paper reviews the operation of this transmission standard and its advantages, in particular as it relates to two-wire transmitters and the associated 4-20mA current loop.

White Paper: Why You Need USB Isolation for Industrial I/O - The USB port has become the most popular method for connecting virtually anything to a computer such as simple flash drives to complex industrial I/O equipment. Most computers built in the last 5 to 10 years have at least 1 USB port with newer computers having upwards of 6 or more. For most home users, having an isolated USB connection is not an issue, however for things such as industrial/remote I/O, data acquisition, IT or medical equipment, isolating a USB connection can be a necessity. This paper will look at the advantages of using USB, what isolation means, types of isolation, when and why USB connections should be isolated.

A Guide to Selecting the Right Isolator - A classical application isolates the control room equipment (computers, PLC, DCS etc.) from field devices which may have different ground potentials. In addition to breaking up ground loops, the isolators protect control room equipment from damaging transient spikes and noise generated in the field. Choosing the proper and most cost-effective isolator requires an understanding of the application and consideration of future expansion requirements.

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