Process Control Loops: Trending PV, SP, OP and Mode

control-loop12Modern manufacturing and process industries are often largely run by distributed control systems (DCSs), with minimal input from operating personnel. This has largely been made possible by the evolution of computer and controller hardware and software.

The basic building block of a process control systems is the process control loop. Process control loops utilize sensors, transmitters, calculations or algorithms, processing systems, and actuators or outputs. Their ultimate goal is to help a process run in a stable, predictable, consistent manner. Some common examples of process variables that are controlled by control loops include tank levels, liquid flows, air temperatures, and steam pressures.

A large industrial processing facility, like an oil refinery or paper mill, utilizes thousands of process control loops. This type of facility also typically utilizes a data historian to store data related to their control system or systems, plus other significant data. This data contains a wealth of information that can be used as a powerful troubleshooting or optimization tool. The trick is knowing how to use it.
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Getting “High Performance” Process Data from your PIMS

high-performance-process-data-for-PIMSThe first step toward understanding and optimizing a manufacturing process is to collect and archive data about the process. Hopefully the system used to accomplish this is a “plant-wide” information system, or PIMS, which collects not just process data, but also quality information and laboratory results, and operations information such as upcoming orders and inventory. Collecting data and putting it in a historian is relatively easy, and most control system suppliers and some third party software vendors offer this capability. The real value of a PIMS is determined by how that collected data is organized, how it is retrieved, and what options are available to help you garner meaningful conclusions and results from the data.

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Guidelines for Effective Schematic HMI Design

Guidelines for Effective HMI DesignMost modern manufacturing processes are controlled and monitored by computer based control and data acquisition systems. This means that one of the primary ways that an operator interacts with a process is through computer display screens. These screens may simply passively display information, or they may be interactive, allowing an operator to select an object and make a change which will be then be relayed to the actual process. This interface where a person interacts with a display, and consequently the process, is called a Human-Machine Interface, or HMI.
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Human-Machine Interfaces for Process Industries

hmiOperating and troubleshooting a modern automated manufacturing process requires seeing and acting on hundreds or thousands of individual pieces of data. Digital control systems and plant-wide information systems have given us the ability to bring all of the data regarding plant status and performance to a single location. The challenge then is to create effective visual displays that allow the consumers of this information to easily understand and interact with the data.

In the world of digital controls, the visual portion of the human-machine interface, or HMI, is typically a configurable, electronic flat panel display. The challenge is to design graphics for these screens which “best” convey the status of the process to the operators.
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3 Key Benefits of Plant Information Management Systems (PIMS)

benefits of a plant information management systemWhen it comes to operating a manufacturing process of any kind, everyone will agree that it is beneficial to have a lot of data. However, simply collecting and storing data does not, by itself, yield measurable benefits. In order to take full advantage of the data, it needs to be organized, archived and then made available in a variety of formats throughout a facility.

This is the function of a versatile and robust plant-wide information system , also referred to as a Plant Information Management System (PIMS), or, alternatively, a Process Information Management System. No matter what you call it, the purpose of a PIMS is the presentation of well-organized data which should lead to informed and cost-effective decisions. Read More

Using Pareto Charts for Quality Control

Using Pareto Charts for Quality ControlThe Pareto chart is a quality improvement tool that is based upon the Pareto principle, the principle that 80% of an outcome comes from 20% of its inputs. Vilfredo Pareto, an Italian engineer and economist, first observed the 80/20 rule in relation to population and wealth. At the beginning of the 20th century, Pareto noted that in Italy and several other European countries, 80% of the wealth was controlled by just 20% of the population.

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How to Use Control Charts to Improve Manufacturing Quality

how-to-use-control-charts-to-improve-manufacturing-overlay2Note: a previous post on Centerlining is referenced in this article. It may be helpful for you to read that first, if you haven’t already done so.

Once a manufacturing process has been centerlined and is running relatively well, it is time to take the next step – measuring and tracking important product characteristics. One method of tracking involves the use of process control charts.

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How To Centerline A Process

centerliningConsistent product quality is important because customers want to know what they can expect from the products they purchase. One way to ensure consistency is to inspect every product after it is made and either reject or accept it.

However, in many cases, 100% product inspection is not efficient due to the variety, complexity, or volume of products being produced. A better way to ensure consistency is to make sure that the manufacturing process runs the same way all of the time. This is where centerlining can help.
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