View Full Version : Fat Fingers and Fat Probes!

05-06-2017, 09:42 PM
Ok, So today I went back to a site which last week had suffered yet another power loss/ spike.
Which had resulted in the 4 Under Floor heating display's to show 100c and error "Out of range" on the Scada display.

Following on from earlier investigations of the circuits last week.
Where both the power supplies and probe connection were disconnected at the display Module (Hoping to "Reboot the display's") failed.

The Apprentice and I agreed we would meter out the relevant 24v dc Fused supplies.
Armed with the trusted Fluke Multi meter and having both discussed that the dreaded H&S had reduced the Probes to useless fat miniscule ends.
The type with the plastic cap which obscures all but a tiny pin on the very end!

So common to earth and Live to one side of the first fuse.. Nothing!
To other side of the fuse... Nothing.
Double check the fuse holder next to the test one.
From earth to the top of the fuse carrier, pushing a little harder to try and ensure a sound contact is made... Nothing.
I pull the red probe away and the fuse carrier comes away with the probe ...Argh!

Flash bang Wallop! Critical alarms (Computer generated) Plant shutdown!

BUT the Temperature displays had reset!!! Brilliant!

It was just a case of resetting and restarting the 2 Unisab controlled screws which were in alarm. ( control circuit supplies had been interrupted and the Unisab was in Alarm)

Big Grins all around, Oh! Yes.
It transpires that the displays were fed by some sort of 4-20ma module which also supplied the computer.
Interrupting the control voltage before these had allowed everything to reset.
Whereas just shutting down the displays did not!

I am still smiling about it now.
I still think the latest fat probes are a pain in the Ar*e. But Hey sometimes you are just born lucky.
The apprentice recons its the luck of the Irish because he has Irish ancestry!

A nice one to end the day all the same.
Cheers Grizzly

Rob White
05-06-2017, 10:01 PM

Sometimes all the skill and training in the world can't beat
a bit of old fashioned good luck.

Take credit because we all know life isn't always so fair :D



05-06-2017, 11:02 PM
US old timers have had some good fortune and fun,although balanced by bad luck and sadness,had my fair share of them all!

05-06-2017, 11:56 PM
So many times this has happened that one has chanced upon the the problem. Always feels good. Some if not all the most amazing discoveries of all time where found by accident.

But one would never admit that in this case, was down to years of experience, life long and ongoing training and that sixth sense gut feeling that only the Grizzliest of Grizzliest Fridgie achieves in time. :)

09-06-2017, 07:14 AM
Hi Grizzly
I like the way Goober put it.
Take the credit mate and tell everyone it was your years of experience that solved the problem.