Surge protection?

[Kari E]

Hi,

When surge protection is needed for trunk and when for the instruments?
We are designing now FISCO segments and trunk lengths are at max about 250m?
Does altitude of 3km and dry atmosphere affect on need?

Thank you beforehand for your comments!

BR,

Kari Elomäki

[sheusel]

Hello Mr. Elomäki,

surge protection is always good to implement it right from the planning phase of the installation. Retro-fit is always more of a hazzle.
If your installation is in a topographical area where lightning often occurs or where other machines or equipment are likely to create voltage surges.

Pepperl+Fuchs offers DIN-Rail mountable and field installable surge protectors for Foundation Fieldbus and profibus.
If you'd like to know more please contact me or check out http://www.fieldconnex.info

Best regards / mit freundlichen Grüßen

Stefan Heusel

Technical Support Manager Bus Systems
Process Automation Division

Pepperl+Fuchs GmbH
Koenigsberger Allee 87
D-68307 MANNHEIM
Phone: +49 621 776-1299
Directfax: +49 621 776-27 1299
Department Fax: +49 621 776-1429
E-Mail: sheusel@de.pepperl-fuchs.com
www.pepperl-fuchs.com

Signals for the world of automation

[Mike ONeill]

I would certainly agree with Herr Heusel that surge protection is better put in place at the start than as a retro-fit. At Hawke, we incorporate surge protection in both our I.S. solution and our non-I.S. solution. In the field, MTL's TP48 is an excellent addition to any transmitter - all it needs is access to the second conduit entry and it doubles as a great carrying handle. (One of my claims to fame is a significant input on its original design, since followed by the P+F unit).
I note that you mention FISCO. It seems odd to me that you are putting in surge protection to prevent induced lightning damage and increase up-time, but still using an I.S. technology with an MTBF a couple of orders of magnitude lower than simple Entity systems such as the Hawke RM100. The Hawke system with surge protection gives an MTBF of 5188 years per segment (assuming redundant power is selected). Suggest you review your FISCO interface with regard to MTBF if your overall aim is to build a system with the best possible availability.
www.ehawke.com/fieldbus

[Peter]

Kari,

MTL offers a range of useful application notes and technical papers that will help you decide. AN9026 is a general guide to FISCO system that includes a section on surge protection. MTL Surge Technologies has produced the FP32 and TP32 for protection of the trunk and instrumentation. The TP32 is the FF compatible version of the TP48 mentioned by Mike O'Neil. You can download or request information from www.mtl-inst.com

Regards, Peter Inns
MTL Australia

[Chris Ground]

Mr Elomaki

It is unfortunate that none of the respondents has actually answered your question and just pointed you to product offerings.

The location of your installation will be directly impacted depending on the frequency of lightning events. There are very few places in the world where there is no impact (north & south pole spring to mind). The effects on your system can be classed in several ways; no effect, moderate effect (some loss of operation, some downtime, equipment loss, equipment unreliability through degradation), large effect (constant reliability issues, downtime & equipment failure).

Once we know your location we can do some calculation to predict the type of effect based on statistical data from Nasa etc. Other effects from internally generated transients will be dictated by type of plant.

Generally, based on experience and calculations, the "rule of thumb" is that if the physical distance between two points of earth (that is between equipment that is mounted, not necissassarily electrically connected, on the structure or in a control room) is 100m or greater horizontaly or 10m vertically then surge protection should be considered.

I would be more than happy to help with your calculations to make sure you understand how you have arrived at your final conclusion of whether or not to fit surge protection.

Best regards

Chris Ground
MTL Surge Technologies
cground@mtlsurge.com

[Hamad_1974]

Dear Chris Ground,

You mention some good information about the surge protection. I heard that you only apply surge protection in some specific areas of the world. For example, in Europe. However, in areas like the Middle East, you would not normally apply this type of protection since it almost never occurs. What do you think about this claim? Just for the record, we do not use surge protection.

Thank you

Hamad Balhareth

[tibor]

Hello Kari,

It is true what Chris wrote about "rule of thumb" (limits are: 100m horizontaly, 10m vertically), but please consider all the surge protector has capacitance and inductance which all together effect to shape of communication signals. Therefore try to avoid to use too much. (How muchs means too much???)

However our practice is: We never use surge protection for indoor application. In outdoor aplication we allways use at the host side and depending on consideration before field devices.

If you need any more please let me know,
Best regards,

Tibor FARKAS
P+F agent
Hungary

[Kari E]

Thank you very much for your advices and comments.
Probably we are not going to use surge protection in our project. Lightnings are very very rare in this area.

Kind Regards,
Kari E

[shilpa]

In a document of surge protector 904-1010%20G%20TAN1010(MTL surge technologies), they have shown surge protector with each device. In my project there are low chances of lightening, and surge voltages are also less often happening. So how should i do?

Your answers are valuable.

[Mike ONeill]

You should consider the risk of the event happening plus the consequences of that event if it did happen, versus the cost of adding the protection and its effectiveness during its installed life.

You say that there are low chances of lightning, and low occurrences of surge voltages.

Now consider if the consequences of lightning and/or surge which then compromised your control system (I've just made these up; pay a consultant or MTL to do this properly);
minimal - no loss of plant operation
moderate - replacement of some plant items, small stoppage
severe - major damage, loss of plant operation, no plant output for days/weeks.

After that, you have something on which you can base a decision.

[rezabejd]

May I suggest another thought - do surge events adversely affect you or your neighbor's conventional 4-20 mA instruments, either the field side or the house side?

If it's not too uncommon, bear in mind the common-mode nature of many devices on a single trunk.

Experience has shown that rigid galvanized steel conduit is also a good preventive measure for all sorts of EMI, RFI, and other electrical maladies.

That said, I have had lightning fry a half-dozen or so conventional 4-20 mA temperature transmitters, which also caused an expensive spurious plant shutdown. I have had no issues with the FF devices, which were purchased with transmitter-manufacturer-supplied surge protection, about a 2% premium at the time.

I don't have any added surge protection on the house end - so might fry a power conditioner someday? If I have a surge protector, do I lose the segment anyhow? If so the choice is "replace a cheap surge protector or an expensive (?) power conditioner" - no process availability difference?

[jberge]

The FF engineering guideline AG-181 says:
"6.3.5 Lightning/Surge Protection
Where surge protection is deemed
necessary (e.g. areas of high lightning
incidence, or where large inductive loads
are started and stopped), surge protection
should be provided. This surge suppression
shall consist of low-capacitance silicon
avalanche diodes or spark gaps, wired for
both normal- and common-mode protection,
connected to the electrical safety ground
grid. Typical installations will be on field
devices installed in tank farms or on top of
distillation columns."
http://www.fieldbus.org/index2.php?option=com_content&task=view&id=218&Itemid=326
MTL Surge Technologies Application Note TAN 1002 rev F dated 6/13/07, Clause 1.1/5.6.1/5.6.3 is similar