Do you have to shunt a timer?

[Skiroy]

I have seen what Capacitors and resistors connected to ice cube relays. I was told it was to prevent damage to the PLC because of the reverse voltage spike that can occur when a coil de-energizes and the magnetic field collapses. I have 24VDC timer that which the coil will be energized by a Allen Bradley Photo Sensor. The output contacts will be going to a light stack. Al 24VDC.

Does the timer need to be shunted?

[underthetire]

Is it a timer relay? Most of the new stuff has led's on them, those are just a diode.

[Skiroy]

Originally Posted by underthetire Is it a timer relay? Most of the new stuff has led's on them, those are just a diode.

Yes it does have LED on it. And its a new one. I also cant figure out how this crappy thing is supposed to be wired it came with no documentation and the terminals are not numbered. It only has A1 and A2, which I hooked up A1 to +24VDC and A2 to -24VDC and it causes my PSU to cut on and off. The attached PDF is all I can find on it. Can you please help?

[underthetire]

I didn't see anything on there that would help. I'm on my iPad though, so maybe I just don't see it. Usually they are labeled on the side of the relay. I hate those btw, a1 and a2 you would thinknshould be the coils, but they are not. Your shorting out the ps.

[Skiroy]

Yeah nothing is labeled. And it said it is a on-delay(On-Delay-Make).

What is a On-Delay-make timer? I think I read its resetting by itself?

If the timer is set to 10secs. My PSU is fine untill 10 secs then it shorts out. Same with every setting. I dont understand this freaking thing.

[Skiroy]

Originally Posted by underthetire I didn't see anything on there that would help. I'm on my iPad though, so maybe I just don't see it. Usually they are labeled on the side of the relay. I hate those btw, a1 and a2 you would thinknshould be the coils, but they are not. Your shorting out the ps.

Okay so if I have to shunt a relay or if I wanted to shunt this timer just to be safe,how would I do it. I know you can use various components but what is the easiest and how do I figure out what value of a cap,resistor ect. to use?
And its just a matter of connecting 1 point of the cap to the + side of the coil and the - side of the capacitor to the -24VDC side of the timer coil,right? Of course getting the Capacitors polarity right.

[Al_The_Man]

You only use r/c snubber if the relay power is AC, a BEMF diode if DC.
That link appears to show a SS timer that has an internal activated relay so it should be taken care of internally?
Also, if using a PLC, what is the reason for using an external timer?
Even the simplest of PLC's have internal timers and counters?
Al.

[Skiroy]

Originally Posted by Al_The_Man You only use r/c snubber if the relay power is AC, a BEMF diode if DC. That link appears to show a SS timer that has an internal activated relay so it should be taken care of internally? Also, if using a PLC, what is the reason for using an external timer? Even the simplest of PLC's have internal timers and counters? Al.

Because we do not have the cable or software to change the program. It is a proface also, and Im only familiar with Allen Bradley PLCs. And finally it would void the warranty if we mess with the PLC. The manufacturer would charge us $4000.00 to do what I am trying to doing for under $300.00

But could you tell me what rating of a BEMF diode I would need? I ask because I may be using a D/C ice cube relay either on this project or another. And how do you connect the diode to the coil? Im pretty sure I know this I just want to make certain.

[Al_The_Man]

A 1N4005 or 1N4007 would be ample.
The positive band on the diode, connects to the positive most terminal on the relay coil.
See bottom of page.
http://www.electronics-project-design.com/diodes.html
What make of PLC is it?
Al.

[mike_Kilroy]

24vdc coil meANS a 100v rated diode is fine. 1 amp good. 1n4003, 1n4004, etc.


+24vdc --------coil-------- common
+24vdc --------|<--------- common

10-4?

[Skiroy]

Why can I not find anywhere that sells a allen bradely timer like these style but for mins instead of only 10 secs?

Can you only buy allen bradley stuff straight from rockwell or what?

The only timers I can find like this are solid state ones that you have to wire in series with your load and I need the N.O. contacts to be on a wjhole seperate circuit.

I need this slim style and it does have to be allen bradely but I prefer a timer relay that doesnt have to be shunted and it has to be for 24VDC.
Can someone help?

[Al_The_Man]

Something in this range maybe?
http://www.crouzet.com/english/catal...r-88865305.pdf
It looks as though it is the same line as before, but maybe better choices?
Al.