Control.com - Nerds in Control

Hi all,
I received an enquiry for a project which requires the PLC control panels to be placed outdoor in the field. The problem is that the external
temperature could go as low as -40 degrees Celsius. Any idea how to
overcome this?

Thank you.

M C Yeow

Wow, that's cold!

Hoffman makes enclosure heaters rated up to 800 watts. I have used their heaters before and they seem to work quite well. http://www.hoffmanonline.com/

Also, Siemens makes an "outdoor" version of their S7-300 line of plcs that is rated -25C to +60C. I am in the process of designing a system using this hardware.

Good luck -
Kevin Hammond
Electronics Engineer
Norfolk Southern Corp.
kshammon@nscorp.com

Incorporate an internal heater into the control panel.

Mark

This is a perfect application for a Modicon TSX Compact PLC platform. The extended temperature range cpu's and I/O are rated -40 to 70 deg C. Go to www.modicon.com for more info.

Nick Liloia

Use a thermostat in the enclosure to control a small heater (search the web for
electrical enclosre heaters). Set the thermostat to some minimum
temperature that you are comfortable with and it will simply turn on the
thermostat when it gets too cold. You should also consider insulating the
enclosure to minimize heat loss, but if it gets warm in the summer this
would be a detriment.

If you have some type of communications to the controller I would also install a
temperature transmitter in the enclosure and monitor that to verify that the
heater is working correctly.

Dean

Obviously the enclosure will be rated for outdoor use and power will
be available. When we need to keep NEMA 4X or similar boxes dry (or warm in
your case) we use strip heaters which most enclosure manufacturers can
provide. You can also safely use the flat heaters used for herpetological
cages or the type used for waterbed mattress warming. Many options
available but the choice should be based on the actual environmental
criteria at the site. Some URL's follow.

http://www.proxim.com/products/accessory/odencl.shtml

http://www.wellmanthermal.com/fireheat.html

http://www.hotwatt.com/

http://www.maoyichina.com/boiler/electric%20boiler/


Carl Ramer, Engineer
Controls & Protective Systems Design
Space Gateway Support, Inc.
Kennedy Space Center, Florida

Usually just a light bulb and a temp sensor is enough to heat the cabinet.

Jeff

Thermostatically controled heaters. see them at www.hammfg.com

If these are going to be pole-mounted or panel mounted controllers out of
doors, you might also think about O'Brien Enclosures. These have been used
successfully in applications on the Alaska Pipeline, etc. They are sewn,
custom fit, insulated enclosures that can be removed for access to the
instrument or control panel.

Walt Boyes

---------------------------------------------
Walt Boyes -- MarketingPractice Consultants
walt@waltboyes.com
21118 SE 278th Place - Maple Valley, WA 98038
253-709-5046 cell 425-432-8262 home office
fax:801-749-7142 ICQ: 59435534

Probably not at 40 below!

You can use a resistance bar heater with temperature control, or wrap the
outside of the cabinet with heat tracing and insulate it (as previously
mentioned, O'Brien bags work great).

Walt Boyes

A 400 watt bulb will put out the same amount of heat as a 400 watt heater,
and cost much less.

Use the wattage you need. 4 X 100 watt bulbs, or 6 X 100 watt bulbs. If you
want to spend money on special heaters, then go ahead.

Jeff

How about a panel heater and a thermostat. In regards to the suggestions
regarding using lights, my experience is that they break or burn out and
sometimes cannot be reliably counted on.

What about the upper temperature range? While PLCs have a good temperature
range, it is not generally good practice to locate them in the field.
Without proper protection(which can
be expensive), it exposes them to environmental conditions such as
temperature cycling which not only causes a temperature problem but a
humidity problem. Other potential exposures are environmental pollutants
and weather extremes. Maintenance abuse will also be higher in the field.

I would also suggest an environmental purge to keep nasty things out.

I would also be concerned with my field I/O temperature exposure.

Bill Mostia
=====================================================
Wil liam(Bill) L. Mostia, Jr. PE
Independent I &E Consultant
WLM Engineering Co.
P.O. Box 1129
Kemah, TX 77565
wlmostia@msn.com
281-334-3169
These opinions are my own and are offered on the basis of Caveat Emptor.

If these are going to be pole-mounted or panel mounted controllers out of
doors, you might also think about O'Brien Enclosures. These have been used
successfully in applications on the Alaska Pipeline, etc. They are sewn,
custom fit, insulated enclosures that can be removed for access to the
instrument or control panel.

Walt Boyes

---------------------------------------------
Walt Boyes -- MarketingPractice Consultants
walt@waltboyes.com
21118 SE 278th Place - Maple Valley, WA 98038
253-709-5046 cell 425-432-8262 home office
fax:801-749-7142 ICQ: 59435534

"Strategic marketing, sales and electronic
business consulting for the small and medium-sized
enterprise: http://www.waltboyes.com"
------------------------------------ ---------

But I strongly suspect that an industrial grade heater has a lot longer
expected lifetime than a 100 watt bulb, especially at extreme temperatures.
Going out in a blizzard at 40 below to change light bulbs can't be much
fun.

By the way, how do you know when your remote light bulbs start burning out?

Diana Bouchard

****************************************************** *************
Diana C. Bouchard
Pulp and Paper Research Institute of Canada (Paprican)
Process Control Group
570 St Johns Boulevard
Pointe Claire Quebec H9R 3J9 Canada
phone: (514) 630 4100 x2376 fax: (514) 630 4120
email: dbouchard@paprican.ca
********************************************* *********************

If the decision to heat the outdoor control panel does eventually lead to the installation of light bulbs as a heat source, be sure to install bulbs for a much higher voltage, such as 230 volt bulbs on a 115volt source. The life of the bulb will be extended by a very significant amount. Also "ramp up" turn on rather than straight on-off will also extend the life by a whole bunch. Just remember to consider that running at half the voltage yields only a quarter of the wattage. I have seen this technique used in remote sites such as the top of
communications towers and the original bulbs are still working after years of operation in Quebec winters!

Gerald Beaudoin

Be aware that i had two panel that burn with the 800w Hoffman Heater! Hoffman have paid for the domage but...

Try using a cabinet heater.....

Mark

Hi,

My recomendation is to use the space heater. We have used the space heaters in our PLC cotrol cabinets working at temp. below -40 deg C.
Sincerely,

Mike Nova

They make internal panel heaters for keeping PLCs and electronics from freezing...

Check http://www.ab.com. This is an Allen-Bradley site.