Showing posts with label temperature. Show all posts
Showing posts with label temperature. Show all posts

Saturday, September 06, 2014

Thermocouples and RTD Tables

The easiest way to measure temperature is with a glass diode like 1N4148 or a metal Transistor like 2N2222. These have a small temperature range, probably -5 to +120 is possible, but non-linear. A copper coil or any metal wire or even a wirewound resistor can work as temperature sensor but the thermal inertia makes it sluggish. IC semiconductor based sensors like LM335 and AD590 are easy to work with and pretty accurate. In industrial environment many types of Thermocouples, Pt-100 RTD and Optical Infra-Red Temperature measurements are used.

Input Levels for Thermocouples and RTD Pt-100. And the ways it has to be used. Thermocouples are selected on the basis on how they are mounted or fixed, the environment, the temperature range that is measured and finally the price you can afford for a particular application. Sometimes mechanical wear or chemical environments may eat away the sensors, so a cost-effective solution has to be evolved.

One customer wanted a special Pt-PtRh very high temperature sensor for molten aluminum. It was very difficult and costly to even arrive at a solution. So a non-contact infra-red sensor may save lot of time-money and even reduce risk of injury.

Thermocouples and RTD Tables

For J, K, and T Thermocouple Read "Temperature" + Room Temperature for mV shown applied to equipment, eg....

If Room Temperature is 25 Deg C and mv applied is 10.777 for J Type STC1000 then reading should be 200 + RT = 225 deg C. The mV shown are for Reference Junction at 0 Deg C.

It would be better if you refer links below, The above table i made long ago, then a Scan with OCR later formatting. It could have errors.

Read More

Tuesday, December 20, 2011

Interface a PC to Measure or Control Temperature

Thermocouple, RTD, Temperature monitoring is central to the majority of data acquisition systems, be it to save energy costs, increase safety, reduce testing time…whatever your reasons, you will need a device to measure the temperature - a temperature sensor.

How to Use Your PC to Measure Temperature

Thermocouples, resistance temperature devices (RTDs), thermistors and infrared thermometers are all types of temperature sensor. Which you choose depends on factors like your expected maximum and minimum temperatures, the accuracy you need and your environmental conditions.

Interface a PC to Measure or Control Temperature

Windmill data acquisition software with Microlink hardware

752-RTD: RTD Resistance Temperature Measurement, Digital I/O, Counting, Analog Output
  • Measure temperature using RTDs or Pt100 sensors, and voltage signals
  • With extra hardware monitor thermocouples and strain gauge bridges
  • Includes the powerful yet easy-to-use Windmill software for Windows: no programming required
  • Connect up to 8 USB units to one PC
Here is a way you can learn, How To Interface PC to the Outside World.

Temperature Control with a PC

delabs Notes

This is a project that will help students learn both hardware and software aspects of a control system. Here you can test out an automation program on a PC with minimum external hardware.

When you implement in the field, the system has to be a dedicated real time uC based product on custom firmware. Systems with OS + Software combination are not known to be reliable in Process Control. But OS + Software is good for Supervisory Systems which get their data from Real Time Controllers.

So a front end controller must be Rugged, Non-PC based and Non-OS based embedded system. With a Robust and Compact (means fast) firmware.

The firmware should be Polling or Interrupt based but with both internal and external watchdog. Most important a Power supply Management that resets system properly over Brown-outs and Black-outs. Even today some Embedded Systems i have to turn off and on after power resumes.

Don't Forget, Multiple Watch Dogs and Multiple Power Management for graceful start of system !! Use one big SuperCap if you want. Else people will go back to Thermostats.

Wednesday, August 03, 2011

Watlow Reference and Guides

Louis Desloge Sr. founds Watlow Electric Manufacturing Company in St. Louis, Missouri, USA, to manufacture electric heating elements for the shoe industry. 1922

Watlow Sensors, Processing and Heaters

'Watlow designs and manufactures industrial heaters, sensors and controllers - all of the components of a thermal system."

The SERIES F4 1⁄4 DIN industrial ramping temperature controller meets the requirements of the most demanding ramp soak controller processing applications.

SERIES F4 Ramping Controller
This ramping temperature controller features a four line, high-definition LCD interface display for quick and easy profile programming and controller configuration.

SERIES F4 Ramping Controller

Watlow reference data provides information for amperage conversions, thermocouple types, RTD tolerances and more.

Watlow Ltd- Reference - Guides and Tutorials

Wednesday, February 18, 2009

Electronics for Measurement Systems

Feedback and Temperature Control

System Model, Types of Feedback Control, On-Off Control, Proportional+Derivative Control, Proportional+Integral+Derivative Control, Proportional+Integral Control, Third-Order Systems..
 Capacitive Pressure Sensors

"Capacitive pressure sensors use a thin diaphragm, usually metal or metal-coated quartz, as one plate of a capacitor. The diaphragm is exposed to the process pressure on one side and to a reference pressure on the other. "


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