Arc Welder Screwing Up Alarm Panel

[inglishg]

A farmer has an alarm system in a barn, and recently he has taken to doing his maintenance in there - this involves arc welding.

Unfortunately, the power obviously interferes with the alarm system, which "locks up" and makes regular beeping noises. Only a full power-down and reset can recover the system.

Any thoughts?

The alarm is powered from the consumer unit through a 3A fused spur, and is NOT on the same circuit as the socket which the arc welder is plugged into.

Thanks in advance...

[jnealon]

Sounds like a case of cables running too close to each other. I had a similar problem with noise being picked up on the keypad wire and crashing the panel.

Check the wiring, are the cables using the same duct to the shed

[james.wilson]

if you can replicate it, ie if the welder does this everytime, personally id discconnect the mains to the panel and see if it still happens when only on bateries. If it doesnt its power related and you will need to filter etc, if it does then its cabling related and you will need to investigate why.

Have had this before when welding happens at or near a roller contact etc. Only way to to fix it is use a decent panel or consider opto isolators etc

[lawandorder]

if you can replicate it, ie if the welder does this everytime, personally id discconnect the mains to the panel and see if it still happens when only on bateries. If it doesnt its power related and you will need to filter etc, if it does then its cabling related and you will need to investigate why.

Have had this before when welding happens at or near a roller contact etc. Only way to to fix it is use a decent panel or consider opto isolators etc

Wow spooky!

I wrote the same thing yesterday (well almost) and just as I was about to post I lost internet connection!

Currently in a hotel in Qatar and the network is dead flaky.

As above diss the mains and think about filtering and possibly using screend cable if it's cable related.

Better quality panels, particualry metal panels which tend to be earthed and therefore screened can help reduce these issues.

Welding can cause havoc especially some of these modern inverter welders.

[A-G]

I'll lay odds it's a veritas panel with a low battery and the mains is going low when the welder is working. Result is low voltage to the pcb and it crashes. Seen it before.

[SUBS]

heres a thought......

Its in a barn, probably a fair way from the primary mains supply, if he's anything like the farmers I've come across, he put the mains in himself.

Is it heafty enough cable ? or 2.5m T&E. Arc welders are basically just a big transformer, and draw a huge current momentarly when the spark is first struck, volts drop on a weedy cable would be quite high for a millisecond or two, ie big spike.

even if the panels on its own cct from the consumer unit, that wont make a lot of difference.

Course, I could be wrong and its done properly.......I aint a sparks.

[inglishg]

Thanks for the replies...

Ok, the power to the barn is sufficient - armoured 10mm cable.

The panel IS a fully earthed metal panel...but I admit it's a rather elderly Optima 2+

The back-up battery is brand new

There are two dualtecs, and NO contacts.

The only cables which run any where near the mains are the bellbox feed and one PIR, and the RKP feed, but none of these run for a significant distance next to a mains feed, and certainly not for long near the socket outlet that the welder is plugged into.

Hope this helps...the fault certainly suggests the power is being interrupted in such a way that the back-up batt can't react quickly enough. Would a larger battery help? Currently there's just a 2.3ah in there, and obviously I could go all the way to a 7ah.

Thanks for all the replies so far - much appreciated!

[SUBS]

Thanks for the replies...

Ok, the power to the barn is sufficient - armoured 10mm cable.

The panel IS a fully earthed metal panel...but I admit it's a rather elderly Optima 2+

The back-up battery is brand new

There are two dualtecs, and NO contacts.

The only cables which run any where near the mains are the bellbox feed and one PIR, and the RKP feed, but none of these run for a significant distance next to a mains feed, and certainly not for long near the socket outlet that the welder is plugged into.

Hope this helps...the fault certainly suggests the power is being interrupted in such a way that the back-up batt can't react quickly enough. Would a larger battery help? Currently there's just a 2.3ah in there, and obviously I could go all the way to a 7ah.

Thanks for all the replies so far - much appreciated!

Not familiar with this panel, but You might try replacing the resevoir capacitor, thats the big one on the PSU. You should be able to measure about 16V DC across it, but if its gone low value or dried up with age, the PSU will still give you 13.2V .

As its heavy, you often find dry joints where they are soldered to the PCB.

You dont need the exact one, up to 50% higher value wont hurt, but make sure its a least the same voltage rating, again - an extra 50% wont do any harm, no real advantage in increasing it above the priginal though.

Not expensive, and wort a go IMO.

Have you tried supressing the mains with a filter from RS or somewhere like that.

Funny things happen around arc welders, once had a telemetry reciever fail that hadnt even been connected to anything, but it had been left on the floor a few yards from a guy welding to a girder.

[hpotter]

I think on those panels the earth into the panel dont go anywhere, just the casing. i.e. psu is floating, not tied to earth.

A big problem with welding kit is RFI.

I'd be looking at rewiring the keypad with screened cable, using an act 12v filter on the power to the keypad, another 12v filter on aux power & a mains filter.

Even if I was fitting a new panel (which wont cost much more than those filters - for a basic), i'd still fit the filters and screen the comms/keypad cable to save agg later.

How bigs this welder (kit I mean) and how close to the panel/keypad does he weld?

[NitroN]

Some welding machines, never had this with an arc welder, can create huge amounts of RFI, wich can affect panels and detectors.

Is the panel mounted in a metal or a plastic box? Metal boxes can protect PCB's from RFI, and may solve your problem.

I am always reluctant to use shielded cable as this can increase capacitance in some panels, reducing wiring run lengths.

If you still still have a problem why not contact http://www.actmeters.com/ and see if they have a solution.

Regards

Nitro

Jeez, I am so slow in compiling my answer, compared to others on this forum....

Regards

Nitro