Tag: Industrial automation
-
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.…
-
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…
-
Phase Locked Loop High Precision Motor Speed Control System
AC generators can be utilized in high precision control systems. The AC generator rotor is rotated by the rotating shaft (i.e. the shaft from the motor being controlled). The output AC frequency is proportional to shaft speed. Zero crossings per time interval can be counted to determine speed for a simple control system. If high…
-
Principle of Operation of Magnetostrictive Position Sensors
Magnetostrictive sensors detect the location of a magnetic ring that slides along a conductive metal tube; in other words this sensor operation utilizes the effect of a magnetic field on magnetostrictive wire to function. The figure below illustrates a Magnetostrictive position sensor: To detect the position of the magnet (in this case, an electromagnetic created…
-
How to Connect Discrete Sensors to PLC Inputs
Discrete Sensor Outputs Basically sensor outputs can be categorized into two types: discrete also referred to discrete or logic and proportional also called analog. Discrete sensors supply a single logical output (1 or 0) e.g. a flow switch used to detect the fluid flow through a pipe whereas proportional/analog sensors provide an analog electronic…
-
NAMUR NE 107 Standard for Modern Instrumentation Diagnostics
NAMUR NE 107 is a standard adhered to by manufacturers during the design and fabrication of instruments. NAMUR NE 107 provides status signals that communicate clear messages and remedies. These status signals or diagnostic codes are categorized into four standard icons and colors making it easier for users to comprehend them irrespective of the manufacturer…
-
Valve Positioners: Function & Types
Basic Features of a Positioner Pneumatically operated valves depend on a positioner to take an input signal from the process controller and convert it to valve travel. In other words, a positioner is a motion control device made to actively compare the stem position against the control signal, adjusting the pressure to the actuator diaphragm…
-
Input & Output Modules of a PLC – Types & Applications
The input/output modules act as the signal interface between the monitoring sensors and actuators, and the controller. Additional they provide electrical isolation, if needed, to convert the input signals into an electronic format appropriate for evaluation by the controller; the I/O modules provide the memory storage and format the output signals for displays and control…
-
The IEEE-488 Instrumentation Bus (GPIB)
A bus in computer systems means a collection of unbroken signal lines that interconnect computer modules; these connections are usually made by taps on the lines. Examples of parallel bus architectures and protocols include: IBM PC bus (IBM PC/XT/AT), the Intel iSBX bus, the MicroVAX Q-bus, the Intel Multibus (IEEE-796 bus), the IEEE-488 instrumentation bus…
-
Programmable Automation Controllers (PACs) – Features & Applications
What are Programmable Automation Controllers? Programmable automation controllers (PACs) are process controllers with an open configuration and possessing the enterprise integration power of a PC-based structure. In other words, PACs are industrial controllers that combine the functionality of a programmable logic controller (PLC) with the processing capability of a PC. Basic Features of Programmable Automation…