relays

[fourperf]

Hi guys, I got my fluctuating spindle speed under control (it was the power distribution board) on my trm. Now what is happening is once in a while say every 4 to 7 days when you power on I get a press jog to reset axis message. When I tap the relay on the new power dist board they click on and all is fine (the relay at k1 and k2) Once they click on the machine runs perfect for days until it happens again. It doesnt seem like it can be a problem with the board as the machine runs great all the other time. Could it be a relay issue thats sticky or something else related to the relay? My warranty runs out in one month and it is so intermittant that if someone comes out the chances of it happening when they get here are slim to none. They told me at Fadal that the new ownership is so strict about warranty that even though I have made them aware about the issue before my warrant expired, once it expires there is nothing they can do. Thats a bummer for someone that does not run the machine everyday.

Mark

[Al_The_Man]

If it is a new board, then presumably the relays are new, so it sounds like it could be a marginal pick up voltage, if the relays are picked up by a solid state device (most likely) then for some reason the circuit, or the power supply to the circuit, is not providing sufficient voltage/current.
There is a pick-up voltage and drop-out voltage for a DC relay, and the drop-out is usually much lower, once it has picked up it will stay picked up untill the voltage is quite a bit lower than the rated voltage.
I would measure the coil voltage when the relay acts up again and when it is working.
Al.

[fourperf]

Originally Posted by Al_The_Man If it is a new board, then presumably the relays are new, so it sounds like it could be a marginal pick up voltage, if the relays are picked up by a solid state device (most likely) then for some reason the circuit, or the power supply to the circuit, is not providing sufficient voltage/current. There is a pick-up voltage and drop-out voltage for a DC relay, and the drop-out is usually much lower, once it has picked up it will stay picked up untill the voltage is quite a bit lower than the rated voltage. I would measure the coil voltage when the relay acts up again and when it is working. Al.

thanks Al, the relays were off the old board. The new one came without new relays. How would a susperct relay act?


It happens sp infrequently that I wonder if I should just get new relays or maybe switch those relays with the spindle forward and reverse relays to see what happens.

Mark

[Al_The_Man]

For the price of relays, I would replace them anyway, and if it persists, then take a voltage reading across the coil.
Al.

[fourperf]

Originally Posted by Al_The_Man For the price of relays, I would replace them anyway, and if it persists, then take a voltage reading across the coil. Al.

Thanks I will, just thinking it through more. If it were a voltage thing when I tap the relays (when they were not powered) why would they click on at that point)?


Mark

[Al_The_Man]

I had assumed you meant that the relays were supposed to be picked up at that point, the board has power on it at that point?
Al.

[fourperf]

Originally Posted by Al_The_Man I had assumed you meant that the relays were supposed to be picked up at that point, the board has power on it at that point? Al.

what actually happens is after I power up sometimes the relays are not powered (they should be) If they are not powered I give them a tap with my finger and then they power up and the machine runs great until it happens again maybe 5 or 6 days later.

Mark

[Al_The_Man]

Originally Posted by fourperf what actually happens is after I power up sometimes the relays are not powered (they should be) If they are not powered I give them a tap with my finger and then they power up

Then that takes me back to my first point/post.
Al.

[fourperf]

Originally Posted by Al_The_Man Then that takes me back to my first point/post. Al.

I guess what I dont understand is why if it is insufficient voltage then why when I tap the relay with my finger will it click on. Not trying to be a pain but I just dont understand

Mark

[Al_The_Man]

When a relay is powered, the coil magnetically attracts the armature to the pole end, it has to overcome the resistance of closing the contact, also the farther away from the pole the stronger the field is necesary.
If the voltage, and hence the field is slightly low, it may be insufficient to attract the armature.
BY tapping the relay, you can jog the armature toward the pole face, and once it gets closer the field takes over, and like I mentioned before, it takes much less voltage/field to hold the armature in place, once it has closed.
Al.

[Geof]

I have seen some relays that have a little metal tab that the armature rests against when the relay is off. Sometimes it is possible to give this tab a little bend so the armature is moved closer to the pole in the off position so the field can pick it up better.