from the SIS department...
Continuous process industries, DCS questions. topic
Posted by Ram on 9 November, 2006 - 10:31 pm
What is the major difference between TMR and QMR technologies? What are the factors influencing in selection of above technolgies?

Posted by Nilanjan Mukhopadhyay on 14 November, 2006 - 12:30 am
1. TMR works in 2 out of 3 Voting
QMR works in 2 out of 4 Voting.
2. Both are SIL3 suitable.
3. Diagnostic may be little stronger in QMR.
4. Normally I/O is redunant by configuration in QMR, whereas in TMR I/O may be inbuilt TMR or triplicated.
5. Sources: QMR: Honeywell, Siemens
TMR: Triconex, ICS

Posted by Avi Chatterjee on 28 December, 2010 - 2:47 am
I don't think QMR is better than TMR. the only reason is that it works in the principle of two dual redundant plc being made redundant again. so more you increase the dependencies by complicating the system you have to calculate the PFD (probability of failure) on demand of each component. as in QMR you have to consider PFDs for two dual redundant PLC then PFD for the link. so if the link fails the you are left with redundant plcs 1oo2D mode. while in TMR you have three CPUs running for the same cause and giving you the output. if one fails you still be with 2 but the voting will be 2oo2D type.

Your use of this site is subject to the terms and conditions set forth under Legal Notices and the Privacy Policy. Please read those terms and conditions carefully. Subject to the rights expressly reserved to others under Legal Notices, the content of this site and the compilation thereof is © 1999-2014 Nerds in Control, LLC. All rights reserved.

Users of this site are benefiting from open source technologies, including PHP, MySQL and Apache. Be happy.

While having never invented a sin, I'm trying to perfect several.
Advertise here
our advertisers
Help keep our servers running...
Patronize our advertisers!
Visit our Post Archive