PLC UPS for power outage

[bobster83]

I was asked to find a PLC backup for power outages. Does anyone have any recommendations of a system they have used and if so, how long will it keep power on my PLC? I have never setup anything like this.

 

[Bullzi]

Do you need DC to AC back up? If DC then I have used the Phoenix Contact Quint UPS System on several builds and have had very good luck.
For AC in panel mount UPS I have used the Allen Bradley UPS and have also had good luck. If you don’t need panel mount then there are hundreds of floor options out there.

As for how long it lasts, that will depend on how much power is drawn from the UPS and the size of the UPS. I normally only power the PLC, HMI and maybe the network switch.

 

[James Mcquade]

we used an apc backup on ab plc5's for years.
siemens on the other hand is picky from what I have been told by my coworkers at another plant. they require a true sinewave output from the ups, not a square wave. the plc power supplies would burn up if they had the square wave input.
the big question is why do you need to keep the units powered up?
WARNING ! even ups backups fail!
your best defense is a good offensive plan. upload the program out of each plc and store it on the network in a safe place.
despite your best efforts, plc power supplies die, cpu's fail.
if you have multiple plc brands, create a vm for each brand to prevent issues, ab and siemens don't like each other for example.
james

 

[mylespetro]

Working in a panel now that has a Tripp-Lite SU1000XLA UPS, very nice little unit. Can't comment on the quality of the sine wave on the output, but it has a lot of convenient features built in.

 

[I_Automation]

I bought an APC UPS years back and the battery went bad in less than 30 days - without any power outages.

A call to APC customer service about the bad battery became "you got 4 weeks of use, just buy a new battery". I asked him if he was saying a 28 day life was OK for a couple hundred dollar UPS and he repeated to just buy a new battery.

I have never bought another APC product since, and have not had any battery failures on CyberPower units that are years old and have been through multiple power failures.

 

[kallileo]

PC Quint power supplies with 24V UPS are great but also expensive.

If you need something inexpensive for a small control system then just for 60-70$ you can buy a Meanwell DRC-100B 24V Power Supply with UPS function and 2x 12V, 1.3Ah batteries to only supply PLC and HMI.
The max output of the DRC-100B is 2.25A. You also have two relay outputs for AC OK and Low battery alarms.

https://www.meanwell-web.com/en-gb/ac-dc-din-rail-single-output-power-supply-with-drc--100b

I have two DRC-100B in operation since December and they seem to be very reliable.
This system is enough to keep the PLC and HMI on for at least 90 minutes on battery power.

You can use DR-UPS40 if you need something more powerful with ability to be combined with a separate 24V power supply.

https://www.meanwell-web.com/en-gb/ac-dc-industrial-din-rail-power-supply-output-dr--ups40

 

[geniusintraining]

The first ones I installed YEARS ago I got from Grainger they ran for years before I left... man they saved them hundreds of thousands of dollars, they were Tripp lite post number 8

http://www.plctalk.net/qanda/showthread.php?t=43235

That was back in 2008

 

[jraef]

If your PLC has a 24VDC power supply running the CPU, then there are lots of options for adding a DC UPS module to it. A DC UPS is just a battery bank and a float charger that connects to the 24VDC system that you already have.

 

[JRoark]

One I'll tell you to avoid would be the SOLA SDUs. I recently had to remove a bunch of them for a client because when the battery goes they just cut out the circuit and kill whatever is downstream. They also say the battery inside is replaceable, and it is, if you almost completely disassemble them.

 

[cardosocea]

Whatever the solution, please do not buy a desk UPS and leave it in the bottom of the panel. It's absolutely disgusting to open up a panel and see that on the bottom plate and making it a pain to add a cable without risking an outage.

I've used Eaton UPS for the longest time from all sizes and must admit they were pretty good. About the battery, you do need to bear in mind the temperature it'll be exposed to as it will reduce it's life span as well as usage.

Depending on the customer, they may want to test it regularly so size it in order for a reasonable test not to take the battery level under 50% as that too will affect them.

There's also the possibility to network the UPS and have your system do a controlled shut down. I worked on a system once that had a few things on UPS power. 2 out of 3 servers would turn off depending on the remaining percentage of the batteries to ensure the process would continue to be monitored and operated manually if required.

 

[OkiePC]

If your PLC has a 24VDC power supply running the CPU, then there are lots of options for adding a DC UPS module to it. A DC UPS is just a battery bank and a float charger that connects to the 24VDC system that you already have.

+1

We use the Rhino battery control modules with 12v sla batteries. We were using the Puls equivalent, but the Rhino is $100 less expensive, has a built in fuse, and its battery fault contact works properly. (The Puls "battery ok" relay doesn't seem to behave like we would expect)

If you want just a few hours of backup:

 

[OkiePC]

Or if you need several days, like this water tower I/O monitor...only has to operate a 4-20 sensor, two digital inputs and a radioline with a combo card.

 

[ndzied1]

You might want to read this to make sure you are not causing any hazards by putting the SLA in an enclosure.
https://www.power-sonic.com/wp-content/uploads/2018/12/Technical-Manual.pdf

 

[James Mcquade]

you have a lot of good ideas here, but in my opinion, you need a copy of the existing program stored on your pc and on the network. any thing can happen.
james

 

[I_Automation]

I tried Rhino power supplies like Okie shows when I started my home solar power bank - before I had solar cells.

A 20 amp Rhino put out a consistent 45 amps and burned up the unit, a 10 amp unit put out 25 amps and I pulled it before it burnt up. Somehow they put out over double the rated current when charging a battery bank. Polarities were correct and the battery voltage was not too low. In my mind they should have shut down on short circuit protection before they put out that high of a current.

I ended up getting a 50 amp manual truck charger at considerably more cost.