hi good afternoon

We have pneumatic control system. Now we want to upgrade to DCS. But we have a difficulty for cable laying. Can we go for wireless transmitter? It is heavy rainfall zone? Is wireless working smoothly in bad weather?

sanjib

 

The only way to be sure is to try a pilot installation. Contact a supplier of either WirelessHART or ISA100.11a transmitters and ask if they will sponsor your experiment to install a transmitter and a gateway in your plant - probably for a utility monitoring point. Start it up and let it run through at least part of a rainy season. It is not necessary to receive every transmission, but a minimum of 75% should be OK for process control.

Rain absorbs RF energy in the 2.4 GHz band where the two standard wireless networks operate. Both of them do both frequency hopping and direct sequence spread spectrum in an attempt to overcome noise and interference in the radio band. I don't know of any hard data to support operation in the rain, so you would be doing all of us a favor to try it on an experimental point.

Dick Caro
===========================================
Richard H. Caro, Certified Automation Professional, CEO, CMC Associates,
2 Beth Circle, Acton, MA 01720 USA

E-mail: [email protected]
Subscribe to the CMC Wireless Report <http://www.CMC.us>
Web: http://www.CMC.us
Buy my books:
http://www.isa.org/books
Automation Network Selection
Wireless Networks for Industrial Automation
http://www.spitzerandboyes.com/Product/fbus.htm
The Consumer's Guide to Fieldbus Network Equipment for Process Control
Buy this book and save 50% or more on your next control system!!!
===========================================

 

Sanjib,

One question... you have mentioned that cable laying is difficult, then how will you over come the laying of power cable(s) for the instrument)?

With Regards, Ramu

 

Many instruments, especially of the Honeywell One Wireless and the wirelessHART design, are battery operated and do not need power. Additionally, power can be brought to the instrument from a light standard or convenience receptacle, wired properly and according to code, of course.

Walt Boyes
Editor in Chief
Control and ControlGlobal.com
555 W. Pierce Rd Suite 301
Itasca, IL 60143

wboyes [at] putman.net
www.controlglobal.com

 

Note that ISA100.11a was explicitly designed for long-life battery operation to be useful in applications where an electrical power source was not available. WirelessHART was also designed for battery operation when 4-20mA is not available. There are some new devices just appearing on the market to power wireless instruments by scavenging energy from available sources such as vibration, thermal gradients, and available light to generate electricity.

Dick Caro
===========================================
Richard H. Caro, Certified Automation Professional, CEO, CMC Associates,
2 Beth Circle, Acton, MA 01720 USA
E-mail: [email protected]
Subscribe to the CMC Wireless Report
Web: http://www.CMC.us
Buy my books:
http://www.isa.org/books
Automation Network Selection
Wireless Networks for Industrial Automation
http://www.spitzerandboyes.com/Product/fbus.htm
The Consumer's Guide to Fieldbus Network Equipment for Process Control
Buy this book and save 50% or more on your next control system!!!
===========================================

 

Dear Sanjib,

I work for Emerson and we have over 1,200 reference sites for WirelessHART networks working successfully in all sorts of processes and environments, including areas with heavy rainfall. We have network design tools to ensure that the network will be robust - these do not require a site survey. All of our WirelessHART devices are battery-powered, with battery life up to ten years, depending on the device and the update rate. I'm trying to cover all of the points in the thread - I think that the last one is that we typically see data reliability of >99%.

Please contact me on andrew.dennant[at]emerson.com and give me more details of your application and I will be delighted to help you to get you the right answers to your questions, and to put your local Wireless specialist in touch with you.

Best Regards,
Andrew Dennant