Battery Backup

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Thread Starter

Peter Thornton

I have a PLC which has to have a battery backup (Uninterruptible Power Supply UPS).
This battery backup has to be small in size, but only has to provide 5-10 mins backup for a small PLC.
It needs to provide an output to tell me when the battery is low, so that I can connect this to an input on the PLC.

Has anyone come across this before, and do you have any product recommendations.

Best regards,

Peter Thornton
 
M

Moses Valdes

my idea is very simple....

if you plc have inputs of 110 V., just connect power energy to one input...and when that signal is not present, one timer must be start and you have to design or take some action...

Best Regards,

PD. If all inputs are 24 vdc, just put one power supply in the enclosure,,,
 
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Johan Bengtsson

Most UPS in the market have some relay that changes status when the remaining power starts to get low, ordinary used for interfacing to a computer (thru the COM-port) but since it (in the ones I have seen) quite often is a relay you can simply connect it to your PLC.

There is another possible solution - of course
if your PLC is to be feed by 24VDC just buy a battery and or the normal source together with the battery by two diodes. You can take the power before the diode from the original power supply and feed it to an input. In order for this to work the ordinary source have to give a little bit higher voltage than the battery.
It is even possible and quite easy to have the same power source feed the PLC and charge the battery at the same time. If you are interested in this contact me again.

This solution is more failsafe than any UPS
since there simply are fewer components that can fail.


/Johan Bengtsson

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P&L, Innovation in training
Box 252, S-281 23 H{ssleholm SWEDEN
Tel: +46 451 49 460, Fax: +46 451 89 833
E-mail: [email protected]
Internet: http://www.pol.se/
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J

Johan Bengtsson

Well, no I have not, but someone on the list might have.

You could ask anyone making ordinary power supplys for DIN-rail if they have something suitable.

(gel-type batteries) I suppose you refere to some kind of Pb batteries, is that right? if it is they are charged with a constant voltage and almost any power supply giving exactly the desired
voltage would be siutable. Typically 2.25-2.30V/cell That means for 24V you want the power supply to give 27.0-27.6V

Depending on the exact way the power supply is made you might need or might not need a diode to prevent the power supply to discharge the battery during power failure. In this case you might
need to compensate the voltage slightly to adjust for forward drop over the diode.

The PLC can then be connected directly to the battery, after you have checked that the PLC really accepts 27.6V of course.


/Johan Bengtsson

----------------------------------------
P&L, Innovation in training
Box 252, S-281 23 H{ssleholm SWEDEN
Tel: +46 451 49 460, Fax: +46 451 89 833
E-mail: [email protected]
Internet: http://www.pol.se/
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-----Original Message-----
From: MIME :[email protected] [SMTP:MIME :[email protected]]
Sent: Saturday, November 11, 2000 6:31 AM
To: Johan Bengtsson
Subject: Re: PLCS: Battery Backup - Question for you.

Dear Mr. Bengtsson,

Your note to the automation list caught my attention. Perhaps you may have already gone through the same problem that we have:
We have used battery backups for small PLC systems, but we have not found a low-cost (< $200) 24V- charger for gel-type batteries that is well adapted for control panels (DIN-rail mount, compact size, screw terminals). Have you found any manufacturer of such chargers ?

Kind regards,
Victor Sancho

PRAI - Proyectos de Automatizacion Industrial S.A.
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Systems Integration & Industrial Automation
Office: Mail address in the USA:
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P.O.Box 153 - 1150 La Uruca 1601 NW 97 Av. Unit C-101
San Jose Suite SJO2265
COSTA RICA - CENTRAL AMERICA Miami, 33172-2853 FLORIDA, U.S.A.
Telephone:+(506) 220-1055 Fax: +(506) 220-1402 e-mail:
[email protected]
 
H

Hakan Ozevin

Dear Mr. Sancho,

Siemens has such a Power Supply/Charger. 24 V DC/15 A, order no: 6EP1 931-2EC01. Price is about 150 USD.

Hakan Ozevin
 
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