MicroLogix 1100 and 240v digital inputs

[SamboQLD]

I have an application where I need to monitor the status of a number of 240vac circuits, unfortunately there is no room in the enclosure to add interposing relays.

Is there a simple way I can run 240vac direct to a digital input? could a resistor be used to reduce the voltage?

As far as I am aware, only 115vac digital input cards are available.


Cheers,
Sam

 

[milldrone]

I have an application where I need to monitor the status of a number of 240vac circuits, unfortunately there is no room in the enclosure to add interposing relays.

If there is room for some 6mm wide din rail terminals then these may work for you.

http://www.phoenixcontact.com/onlin..._P-16-01/82c88f5d-4d57-42c8-b56d-249e69159fb4

http://www.phoenixcontact.com/onlin..._P-16-02/aac5d024-0e1a-4462-a6da-0a4fe3c95645

http://catalog.weidmueller.com/catalog/Start.do?localeId=en&ObjectID=8556020000

http://dkc1.digikey.com/us/en/tod/Omron/G2RV_NoAudio/G2RV_NoAudio.html

http://industrial.omron.eu/en/produ...s/industrial_plug_in_relays/g2rv/default.html

http://www.automationpart***press.com/Weidmuller-8556020000-Relays-contact-connection/dp/B006HAB1HI

 

[DamianInRochester]

The inputs are pretty high impedance, so theoretically you could probably just use a simple voltage divider circuit. Aside from the safety concerns and possibly confusing the next guy down the road, you would also have to worry about the case where you loose your resistor tapping to neutral and having the full 230VAC being seen at the input. So you are probably better off just putting an extra box next to this one and putting the interposing relays there.

My question would be, how hard would it be to convert your inputs to 115vac? Obviously with all the pushbuttons and limit switches it would be as simple as sourcing the 115vac to where the 230vac previosuly was. Most sensors like AC proxes will work on a full range of 115vac and 230vac. There may be just a couple things that actually require 230vac and you could deal with those separately.

 

[Tom Jenkins]

I'm against baling wire and chewing gum style fixes like voltage dividers and such. If there is no room in you panel I suggest getting a terminal junction box, mounting it adjacent to your main panel, and installing some of the compact interposing relays the Mill Drone reccommended. By the time you are done it will be less expensive than the other soulution, more reliable and clan, and will simplify for future trouble shooting.

 

[SamboQLD]

Thanks for the suggestions... those 6mm wide relays seem like the way to go, I might just be able to squeeze them in.

Cheers.

 

[Lancie1]

As far as I am aware, only 115vac digital input cards are available.

Sam,
There are some 240 VAC input modules, such as the Allen Bradley Flex I/O "240 VAC Digital Input Module 1794-1M16".

Also other brands have 240 VAC input modules, such as Fanuc 90-30 and 90-70 PLCs, Omron ZEN AC Input Expansion Module, Square D Sy-Max, and the Automation Direct P3-16NA AC Input Module. I think the old Schneider Modicon would accept 240 Volts. There probably are many others.

 

[leitmotif]

I would consider using instrument or small control transformers.

Even better would be current transformers with a resistor across the 5 amp output to yield voltage compatible with PLC input. Now you know not only that the receptacle is hot but you know if the load is running or not.

Dan Bentler

 

[OkiePC]

By now they shoulda come up wid' ...:

-1000 to +1000V AC or DC, 0-100 amp input or output modules with 128 bit resolution.

Seriously, though, +1 for Omron, Phoenix or Wago terminal size relays. If you use A/B be sure to order the correct base for the voltage.