Temporary building power problem

[equityfarmer]

I am on a project here in Las Vegas working on a temp power crew. The problems are with 1p 20A Gfi breakers. Siemans panels... We have 4 different risers feeding different areas. All areas seem to be affected. We have tried bringing a ground from another area.... checked for loose neutrals. A panel does not even need a load on it to trip. Sometimes all breakers trip at once. This is a high rise hotel that is being built steel and concrete. The iron workers have their equipment grounded to the iron. They are shooting with the nelson stud machines continuousluy and arc welding.... has anyone heard of defective breakers by siemans? Any ideas??? Thanks Bob

 

[waross]

Are any of the GFCI protected circuits running close to and parallel with welding cables or welding current return paths?
respectfully

 

[rbulsara]

If the circuits are long, capacitive leakage itself will nuisance trip a 3-6mA GFCIs. If circuits are long, GFCI outlets near the tools will be more effective than GFCI breakers.

May be some tools are defective to have enough leakage current to trip a GFCI.

 

[equityfarmer]

We are thinking that the welding cables are causing our problems. We have tried bring additional grounds to the transformers but to no avail.... The runs are relatively short. 40 feet of wire between panels. In some cases the entire panel will trip with out any load on it.... Thanks for the help so far... now I need to know what do do about the return path current from the welders...thanks...

 

[waross]

Have you checked the sub panels to see if the neutral bnding screw or connection has been removed? There should be a connection from the neutral to ground at the main panel only.
If the neutral is connected to the ground at the sub panels, the neutral may share welding currents that should be traveling only in the steel structure. A sudden surge of welding current may cause a voltage spike on the ground grid. If the ground and neutral are improperly interconnected, this may result in a voltage/current pulse on the neutrals (the voltage pulse may cause a charging current due to the capacitance of the cables).
Many panels have a green screw installed in the neutral bar that connects the neutral bar to the panel "can". This screw should be installed in the main panel only and removed from all sub panels.
Note: Some panels use a grounding jumper instead of the screw.
This is another instance of the reason that building systems should have one and only one connection between the neutral and ground.
respectfully

 

[rbulsara]

Provide some rational of your "conclusion" that welding cableis doing it? What do you mean by whole panel tripping?

The main trips or all GFCI branch breakers? Does the main have GFP or GFCI?

Trips on what? Overcurent/ GF? If it trips without load, it has nothing do with any load, inclusing welding. Does the welding fed off the panel(s) in quesiton?

I would look for a faulty machine or cable fault that connects to this panel.

Or check the GFP (ground fault relay) setting, if there is any.

 

[equityfarmer]

More INFO
Now we part of our p[roblem solved. When you "key" a Motorola radio near a panel with the door open every breaker trips at once. When you key it near the panel with the door closed only one or two will trip. So some of our issue is people leaving panel doors open... Now the part to add is that there are swing stages plugged into 2pole breakers and this is a motor load possibly sending spikes or dips.... Last week a High Voltage specialist was called in and is "monitoring" the voltage and recording to analize later. They think it could be an imbalance on our 3 phase distribution panels....when one floor has alot of activity that may cause an imbalance and who knows..... Any siemans reps read these post??? Anything anyone could add would much appreciated....Thanks....Bob

 

[davidbeach]

No High Voltage to worry about, no need for a "High Voltage specialist". High Voltage doesn't start until you get above 69kV; everything below 1000V is low voltage, including your temporary power. sounds like someone is trying to rip you off, promising expertise they don't have.

 

[equityfarmer]

Thanks for your concern but I probably mis spoke calling this company a High Voltage specialist. They are equipted to monitor our problems because of what they do primarily. Our company does not have the monitoring equipment. Anyways... looking back on other post.... The welding does not feed off any panels in question. And the main ckt breaker does not trip only branck gfci breakers trip. Tripping the entire panel with the Motorola radio does not happen on all panels. Anothe consideration... We are feeding a lighting load that consist primarily of 400w MH fed overhead by MC . So the installation is more permanent. No chance of isolating by using SO cord etc... So we are still in search.. I will update after the monitoring is "read". Thanks to all.....

 

[rbulsara]

Metal halide or any HID circuit will trip GFCIs. Leakage current of HID circuits usually are enought to trip GFCIs. Why do you even have GFCI for HID lights? Get rid of GFICs.

And if choose to for come obsucre reason you need to use 30ma or higher sesitivity Equipment GFCI and not 3-6mA personnel GFCI.

I find it hard to swallow the correlation between radios and GFCI trips. Involve someone experienced consultants.

 

[dpc]

I can believe that a VHF transmitter very close to a GFI breaker could cause it to trip when keyed. Should be simple enough to verify through repeated testing.

I have seen a 5 watt transmitter cause an electromechanical instantaneous trip element to operate (tripping a 600 MW unit), so I think it could trip a cheap solid-state device such as a GFI breaker.

As for imbalance - I doubt that is the cause unless something is miswired (neutral lead connected to ground). But normally, the GFI breakers are so sensitive that you find those mistakes pretty quickly.

 

[ozmosis]

equityfarmer
to answer your other question; yes, there are Siemens people within this forum but if you need somebody from Siemens USA to assist with your site issue, I strongly recommend you go through the Siemens channel for support:

http://www.sea.siemens.com/support/contact.asp