Monday, May 7, 2018

Industrial Control Panels and Instruments

Instruction Manuals of Process Control Instruments and Industrial Automation Solutions, Control Panel Diagrams, Wiring, and Facia.

Temperature and Pressure Controllers form a large part of Process control Instrumentation. Then you have Flow, Humidity and many more custom parameters.

Electronics Theory - Industrial Control Panels

All Real Life Physical Phenomena are reduced to Analog Numbers by Sensors and Transducers. This analog value is amplified and linearized and brought into standardized windows like 1-5 Volts or 4-20mA and more.

Industrial Control Panels and Instruments

These Analog Values go to Analog Closed Loop Controllers or Meters for Measurement and Control. In Embedded Controllers, the Analog is converted to Digital ( At least 12 bit, 8 bits are cheap not used for industrial automation, more than 16 bits is not required as sensor accuracy/linearity never transgress such precision )
Embedded Process Controllers may use Microcontrollers with Floating Point Arithmetic, Lookup Table, Logic and Basic Math. Advanced Controllers may use DSP and Complex Algorithms for Adaptive control. (self learn, fuzzy logic.).

Monday, April 2, 2018

Mixed and Interface Circuits

Most of the sensor interface and instrument inputs are analog; even if it event based like a limit switch, analog circuit protection and signal conditioning is required before it reaches the level sensitive digital circuit blocks.

Starting with Schmitt triggers and to the VCO and A-D Converters, are grades of Mixed Circuits. I feel Comparators like LM339, Timers like the 555 and Phase Locked Loop PLL are fundamental mixed circuits as they have a analog voltage detection.

DSP and uC with built in A-D or D-A or even SOC are Public ASICs and Fall in the Embedded Systems Block. Public ASICs are not user specific, they can be branded, numbered and provided with Application notes for the use of the Design Departments of any firm. User Specific ASICs are custom built and have only an application with that manufacturer for a Specific Product type. This also protects the IP of Code and Device Design. Custom ASICs are limited to the Platform and Technologies for which they were designed. Then we have programmable and configurable chips other than uC for logic like PLD, CPLD, FPGA and SOC, there is even some talk of mixed or analog configurable chips.

It would be nice if they made a breadboard chip with 12 opamps, 24 comparators, Some PLD and a couple of uC. Then we certainly need software trimmable or tweakable Resistors and Trimpots. This is the Magnum Opus of EDA. A EDA Chip Printer may be coming soon ! (Affordable by small firms).

Read More - Mixed and Interface Circuits - delabs

Friday, February 23, 2018

Control Interface to PC Ports

A computer can be used to control or automate systems. From turning lights on/off at your home to shutting down motors or heaters in industries. Speed control and PID Control too.

PC based Instrumentation is easy to implement using USB Devices and Plugin Cards for Test and Measurement.  Most instruments can communicate with PC on the GPIB interface.

Control Interface to PC Ports

USB interfaces have made such PC based Data Acquisition and Controls much easier. In the early days it was Printer Port and Serial Port. The future is for Wireless Device Networking.

When Intelligent Devices (embedded systems) are privately and securely networked, it is called the Intranet of Things. This is like a Home-Office-Business private closed Cloud. This is ideal for Home and Infrastructure Automation and even Big Business or SMB Automation.

This can get you started too. The few examples above show an instrumentation - Logic Analyzer 'Like' interface and a relay-display driver circuit. They are examples i tried for students to try out and learn.

Control Interface to PC Ports.

Monday, January 1, 2018

A Practical 2018 Engineer

Making Simple, Safe, Sensible and Sturdy Electronic Products should be the aim of any Electronic Engineer. A prototype should be developed to become a Cost effective Solution.

A Practical 2018 Engineer

Never ship Beta products or sell them at High Prices. New products if not tested and developed completely should be marked Beta and Sold at lower prices. When a manufacturer is on "The Rising Edge of the Learning Curve" (delabs phrase 1998) for a product line, he has to sell products marked beta at lower price or wait till the development is mature. I have learnt this from my own blunders.

In Software Beta markings are clear, even in Webapps they mention. Hardware Industrial products are never sold in beta state. Then the Smartphones and Tablets boom led to many beta products being sold to consumers at regular prices. This should be avoided to protect the brand name and the reputation of that business segment itself.

Thursday, June 22, 2017

Test Measurement Instruments

delabs designed and built many custom "engineered" Test Instruments. They were not prefect, as only one or two were fabricated. That means it will be costly to produce such instruments. It is just like tooling, you have to make some numbers to recover costs, or price it very high to compensate for the wastages and iterations. But things are better off now for building custom instruments. Yet a design firm has to make modules and keep ready, then put together a solution/system, program and ship.

Test & Measurement Instruments

When making custom equipment, you have to have an extended service agreement like 5 years. Also request a minimum order of at least 5. Make your R&D and Inventory Modular. That way it is profitable and some money available for reinvestment on instruments and Equipment for calibration and quality.

Test Measurement Instruments by delabs

Test and Measurement is all about Measurement or Metrics. Without this, every other part of electronics becomes like boneless entities.

Relationship between Instrumentation and Automation - In Test and Measurement and Industrial Process Control a common factor is instrumentation. The measuring aspect is common to both. T&M instruments are used in Testing, Research,Automated Testing, Troubleshooting and Servicing.

Instruments designed and built. (long ago).
Process control Instruments are used in Production Lines made of Machines in a Factory. It could be Counters and Timers used for Textile or Steel Industry. It can also be Temperature and Pressure Controllers used in Oil Refining or Food Processing.

So you see a difference. We have handheld Test Instruments like DMM and Scope and We have Handheld Instruments for Gas Monitoring or Humidity too. In automated testings we have rack mount test instruments. In Control panels we have Rail Mount carrying DIN standard Instruments.

Monday, April 24, 2017

Instrumentation and Measurement Circuits

Analog Circuits are the core in any instrument design, Even in a Instrument with Digital or uC control. The Interface to the Real World parameters is Analog. High Speed Analog and High Energy Measurements are the challenging areas.

T&M and Process Control Instrumentation have many things in common; but the conditions in which a Industrial Instrument works, may be very unfriendly.

Instrumentation and Measurement Circuits

Industrial Instruments are used both in Clean-Cool Control Rooms and also in a corrosive, humid, hot and vibrating industrial environment. Even high levels of Static, Magnetic influences in conjunction with spikes and brown outs can be expected.

Instrumentation and Measurement Circuits

Test and Measurement instruments are of two types, by way of its usage; Portable and Benchtop. Portable Instruments will consume low power, insulated and rugged. The Product Safety features are more stringent as they are HandHeld or slung over the shoulder. Some features and specs are sacrificed. The Benchtop version has more front panel space and can interface with other instruments or systems. More accuracy and features can be accommodated in this.

Basic Measurement
Other Circuits on this page are - in PDF -
  • Linearizing circuit  using opamps
  • Universal signal conditioner differential amp
  • Simple MilliVolt Source
  • 0-2V to 4-20mA Converter
  • Analog averaging circuit with Opamps 

Monday, February 13, 2017

Process Control Application

A Closed Loop Control System is the most important aspect of Maintenance, Regulation and Stability in any Live Process. Nature itself is self regulated in an intricate fashion, a keen observer can notice the subtle controls. In Human Created Industrial systems we have Process control as a complex science. We can start by understanding a Simple One.

Process Control Application Notes

When you fill a Bucket with water, You keep an eye on the Level of water, as you open the Analog Tap, which is an equivalent of a Motor operated Valve. Your Eye is an advanced Optical Sensor, which is able to sense the level by the computation in the brain, which in turn operates the muscles of your hand, thru the nervous system. The hand along with the Water Tap is is the Actuator. As the water fills up close to the top, you start reduction of the water flow and keep observing, then as it tops up, you tweak the tap to a trickle. When it reaches the limit you shut off the tap.

Closed Loop Control Systems

While you are half way filling the bucket, what happens if you take a short nap, or a friend comes by and you are get absorbed in conversation, the water overflows and goes waste. Then someone raises an alarm after the Runaway process happens. This is of minor consequence, but it is not so in the case of Temperature, Pressure and also many common systems like the driving of an Automobile. Remember the gears, brakes, accelerator to control and steer the car to the correct destination, a Runaway Process causes an accident.

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