PLC Battery

knichols · Nov 19, 2007

I have a plc system which loses it program when the battery dies. The end user may leave the machine off for extended periods of time, and the battery just goes. I wonder if any of you guys know of a system, which would charge a battery when external power is present. This would give the battery the maximum chance of success. I have googled extensively, but have only found overkill solutions meant to power an entire computer. Thanks in Advance...

PeterW · Nov 19, 2007

I would normally design the system so that the PLC remains powered when the panel is isolated.

The PLC being powered via the 'live' side of the panel isolator.

TConnolly · Nov 19, 2007

Does your PLC support an eeprom? If so then I recommend using one and configuring the PLC to load the program from eeprom on start up.

Oakley · Nov 19, 2007

Let me guess ...

An Allen Bradley ControlLogix L5x?

If so, there has been many many discussions on this issue. Other than designing an elaborate battery charging/distribution system, I'm afraid you are stuck with the proposed solutions.

knichols · Nov 19, 2007

Its actually a no-name pci card system. I saw the control logix folks talking about this issue a bit, and hoped someone had come up with something. You are right that it should have been designed with flash memory and a good startup intialization.

Oakley · Nov 19, 2007

What is the system doing?

Would it be easy enough to convert to a PLC program? Even the SLC series or the CompactLogix series would be good fits for a basic system.

I'm sure that others would chime in and suggest AD or some other type system. I'm just partial to AB since I have been dealing with them for so many years.

jrwb4gbm · Nov 19, 2007

Here's another brute force suggestion:
Get a fairly large UPS and connect it in between the 120v power source and the PLC power supply. This is similar to the suggestion that Oakley made.

PeterW · Nov 20, 2007

jrwb4gbm said:
Here's another brute force suggestion:
Get a fairly large UPS and connect it in between the 120v power source and the PLC power supply. This is similar to the suggestion that Oakley made.

Depends on how long they switch off, if they switch off every wekend for all weekend then a UPS would be useless.

I still say maintaining power is the best solution, maybe with a EEPROM if possible.

When you power up and power down are possible times of failure, so keep it powered up.

surfside_auto · Nov 20, 2007

I agree, EEPROM would be best. Just burn the card and set the program to boot from the EEPROM and it doesn't matter how long the PLC is powered off.

Lancie1 · Nov 20, 2007

I would normally design the system so that the PLC remains powered when the panel is isolated. The PLC being powered via the 'live' side of the panel isolator.

That is sort of illegal here in the States (National Electric Code and all). To make it legal you would have to install two isolators, and a big warning sign on the front of the panel that warns of more than more one power source, and exactly how to kill both sources.

PeterW · Nov 20, 2007

Lancie1 said:
That is sort of illegal here in the States (National Electric Code and all). To make it legal you would have to install two isolators, and a big warning sign on the front of the panel that warns of more than more one power source, and exactly how to kill both sources.

In the UK you would be required to put a sign stating that not all power in the panel is made dead with the isolator, inside there would be an isolator fed from the 'live' side which would be labelled and the terminals supplied would norm have a clear plastic cover with the old 'live' electric symbol on.

I was just stating what I would do, not the specific actions to do it.

PLC Battery

knichols

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TConnolly

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Oakley

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knichols

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Oakley

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jrwb4gbm

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surfside_auto

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