Feedback transformers

[inick2005i]

Hello forum, I have an oddball question and wanting to pick some electrician brains on here.



We are currently using starter contacts on 4 of our kiln fan motors to give running feedback. The contacts are used in series to keep a "Purge Complete" relay latched in the entire time the burners are on. The motors are also electrically latched ON using another auxiliary starter contact. Our PLC's do not provide the run command, so we don't have any fail alarms if we lose feedback.....but we do lose our purge circuit if we briefly lose feedback. The fans continue to run, so troubleshooting involves 4 dry contacts and 4 relays that are pulled in by those contacts. We have the feedbacks data-trended, but we think we are losing it in-between trend updates and possibly even in-between PLC scan times. Enough to drop a latched relay out, but not enough to see in PLC or trending.



My question is regarding feedback transformers. Since we have small buckets and limited space, the larger sized 480/120 transformers won't fit in the bucket (to use as feedback). At one time we were able to source some small (like golf ball size) transformers to convert 480v to 120v, but can't seem to source those anymore.


Does anyone know of any small transformers 480 primary 120 secondary that we could hang off the starter output to give a reliable feedback? The dry contacts from the starters eat our lunch every few years, wish we could eliminate them.


A VFD would be the ultimate fix for our dilemma, but that would be a very large chore. Appreciate any feedback (pun

 

[TWS]

You could swap your motor overloads for an electronic overload relay that can be networked. Or you could use CT's with relay outputs, like this: https://www.functionaldevices.com/products/building-automation/details/RIBXGHF/.

I would look for something intermittent (relay, wire ect). causing the purge complete circuit to fail. I am assuming something has changed or has this been a continuous problem?
Post a wiring diagram someone here will help you.

 

[Phil Buchanan]

Here you go https://www.functionaldevices.com/products/lighting-controls/details/LT150-120/

 

[inick2005i]

You could swap your motor overloads for an electronic overload relay that can be networked. Or you could use CT's with relay outputs, like this: https://www.functionaldevices.com/products/building-automation/details/RIBXGHF/.

I would look for something intermittent (relay, wire ect). causing the purge complete circuit to fail. I am assuming something has changed or has this been a continuous problem?
Post a wiring diagram someone here will help you.

Thank you for the reply, those CT relays look like a great way to get running feedback. I'm going to look into those and see if I can find one rated for 480VAC. We aren't currently having any drop outs, but earlier in the year we had several and a dirty auxiliary was thought to be at blame.

 

[Mickey]

Thank you for the reply, those CT relays look like a great way to get running feedback. I'm going to look into those and see if I can find one rated for 480VAC. We aren't currently having any drop outs, but earlier in the year we had several and a dirty auxiliary was thought to be at blame.

The one posted fits your needs. See pdf

 

[inick2005i]

Here you go https://www.functionaldevices.com/products/lighting-controls/details/LT150-120/

Thank you Phil, I'm going to look into the CT relays mentioned above. This transformer is 4"+ in size. We stock some that are this size, they are too big to fit comfortably in our buckets. The transformers we were sourcing years ago for feedbacks were only 2" in size at most. They were tiny little things.

 

[inick2005i]

The one posted fits your needs. See pdf

Thank you, Mickey!


Thankful to everyone for your help on this!