Tight space simple requirements & need some equipment suggestions

[xprtcp]

While it might be possible to use the Click PLC power supply, I never suggest using the same power supply to power both Electronics and Coils. Coils cause too much interference and if not properly snubbed will eventually kill the electronics. Power supplies are so inexpensive any more it just makes sound practice to use two.

Which coils? Not interposing relay's coils? The Click high current block is direct connected to the Click so that should be protected by Click, right?

The two remote relays are in other equipment and cannot be changed to 24 VDC. The six solenoid valves likewise cannot be changed to DC.

(This is a retrofit to provide time delay due to a change in the process plumbing.)

The distance should be fine assuming a proper wire gauge is used.

The wire gauge is 12AWG for all conductors outside of the panel.

Battery Backup, this is easily fixed by changing the retentive ranges in the PLC.

retentive ranges I have no clue what that means. Does the Click have that option?

Proper Sizing and Protection - Yes. All coils should always be snubbed. More so when it is DC powered.

Where can I get the right snubber? The solenoid is marked "5A 120VAC". The remote relays are not marked but are also 120VAC. It is possible to install the snubbers on both the relays and the solenoids close to the coil.

 

[xprtcp]

Hi, xprt!
Have a look at these RC plug adapters from Murrelektronik.
They takes the spike from the solenoids, and protects your relays.

Kalle

Edit: Aha! It must be these you call 'snubbers', right?

Yes, a snubber seems to be a resistor and capacitor in series installed in parallel with the contacts.

This one looks like it has an LED too.

Is this the one you are suggesting? https://onlineshop.murrelektronik.c...UP=1&BEGIN=1&sLanguage=English&pageturning=10

How is it installed?

It does not appear to be equipped with leads for installation at the coil.

 

[xprtcp]

I would use interposing relays on the Brick PLC...because it's a brick, if you lose an output, you replace the whole thing...

Would this be better than the Click approach with the high current output relays? Two Click four relay blocks leave two spare relays, and six spare relay points on the Click PLC itself. Am I right?

If you can get 24vdc into the box, and use a 24vdc version of the PLC, it will usually run cooler, be less expesive, and may make your choice of interposing relays even wider since you can use 24vdc coils and simple transistor outputs on the PLC. This means switching the input voltage to 24vdc too, which has other advantages, the caveats being noise immunity and distance.

Getting 24VCD into the box is just a matter of space. It should not be a problem if it is small enough. Better still, if it is DIN mounted on the same rail with the PLC. . . There are 14 inches of space for a DIN rail.

If you stick with AC, then that list looks like good recommendations. With only 6 relays, I guess you can go about 1.7" wide on the relays, making them easier to handle, but still fitting across one din rail in a 12" wide box...

Since this is a retrofit to provide time delay, everything is 120VAC now.

What's the ambient temperature in which this box will be located?

A most important question! The equipment shares a NEMA 4X SS outdoor (in Maryland) box with the controls. Sorry I did not think to mention this in the specifications. Click says theirs is good to 70C.

 

[MikeW]

Post 13 ...
Distances? The control system that is providing the contact closures is in the same cabinet. (BTW, the cabinet is NEMA 4X SS in the sun in Maryland.)The relays are <100' via conduit with other conductors. The solenoids are <100' likewise in conduit with other conductors. ...

"via conduit with other conductors." Are you going to mix AC & DC wires in the same 100' of conduit or will it all be AC only? Mixing AC and DC in the same conduit is not recommended.

 

[OkiePC]

Most PLCs will handle the heat pretty well, but power supplies in a small box with the PLC may create enough heat to put your PLC over its limit.

There are some calculations you can do to determine how much heat can be dissipated based on the size and construction of the panel.

http://www.hoffmanonline.com/stream_document.aspx?rRID=233309&pRID=162533

Using the high power relay output modules really looks pretty good since they're so cheap. Usually, (most PLCs) with 8 or more points you hate to replace a module due to one sticking relay because they typically cost a couple hundred bucks. Not so with the Click. $44 for four points and no need for separate interposing relays...I think the Click folks have given you some good answers.

 

[xprtcp]

"via conduit with other conductors." Are you going to mix AC & DC wires in the same 100' of conduit or will it all be AC only? Mixing AC and DC in the same conduit is not recommended.

The existing system is AC only. The remote coils are AC and there is no intention of installing conduit as it is all cast in concrete now. There is no reason to run DC outside of the cabinet which has both inside now.

I would prefer to stick with AC as it is a retrofit and needs to be as simple as possible for troubleshooting in the future.

 

[xprtcp]

Most PLCs will handle the heat pretty well, but power supplies in a small box with the PLC may create enough heat to put your PLC over its limit.

There are some calculations you can do to determine how much heat can be dissipated based on the size and construction of the panel.

http://www.hoffmanonline.com/stream_document.aspx?rRID=233309&pRID=162533

Using the high power relay output modules really looks pretty good since they're so cheap. Usually, (most PLCs) with 8 or more points you hate to replace a module due to one sticking relay because they typically cost a couple hundred bucks. Not so with the Click. $44 for four points and no need for separate interposing relays...I think the Click folks have given you some good answers.

Thanks for the link to Hoffman. I think the cabinet is about 8 X 20 x 40 inches. . . not sure.

 

[KalleOlsen]

Yes, a snubber seems to be a resistor and capacitor in series installed in parallel with the contacts.

This one looks like it has an LED too.

Is this the one you are suggesting? https://onlineshop.murrelektronik.c...UP=1&BEGIN=1&sLanguage=English&pageturning=10

How is it installed?

It does not appear to be equipped with leads for installation at the coil.

This type is installed by unscrewing the plug from the solenoid and put it inbetween. There are more types depending what kind of plug you use.

To select the best unit, do as I do; call a salesman.
Here's the address and phone in US.

Murrelektronik Inc.
1400 Nortbrook Parkway
Suite 300
Suwanee, GA 30024

Phone: +1 770 497-9292
Fax: +1 770 497-9391
E-mail: [email protected]
Website: www.murrinc.com

Kalle

 

[xprtcp]

Thank you for your comments and the contact info. I have called.

 

[xprtcp]

What do you think of the Tri-PLC equipment? It looks like I will have to use the 24VDC signals and a power supply (and snubbers), but otherwise everything else is out of the box.
http://www.tri-plc.com/products.htm

Update: just read their tech support policy...no phone support mentioned, just email. That could be a deal breaker as I often need support while in the field.

 

[xprtcp]

I found this software for heat calculations. It is free too! It is so simple that I could use it. http://www.eldon.com/en/Applications2/Thermal/Thermal-Management-Software/

 

[DamianInRochester]

I'd give a plug for a small Unitronics. Perhaps something out of the JAZZ line.

 

[xprtcp]

I'd give a plug for a small Unitronics. Perhaps something out of the JAZZ line.

It appears that interposing relays would be required. The current capabilitys may be <5A.

One JAZZ has 11 relay outputs.

I was unable to locate prices.

 

[xprtcp]

Thank you for your comments and the contact info. I have called.

>24 h still no response...

 

[xprtcp]

What do you think of the Tri-PLC equipment? It looks like I will have to use the 24VDC signals and a power supply (and snubbers), but otherwise everything else is out of the box.
http://www.tri-plc.com/products.htm

Update: just read their tech support policy...no phone support mentioned, just email. That could be a deal breaker as I often need support while in the field.

Correction to the Update: They do offer phone support as well as email.