big unresolved problem for 2 years

[dean7828]

Hi guys ill get straight to the point, I'm on a 3 phase system trying to resolve what many have tryed and failed over the last 2 years, the problem is compact pll lights dimming right down intermitently throught, actions taken are as followed...all other circuits switched off still problem, monetring device on incomer set up twice and left for a month and found no diffrence in voltage, voltage at ligts ok at 237v, swapped phase that circuit is fed from and still persists, tryed new light still same incoming voltage ok haven't tryed zs yet but now going to try

Be great to get this problem finaly resolved so please come forward with you're vews chers guys

 

[Paul.M]

Have you done a R1+Rn? Maybe a simple loose terminal fault.


Edit... Have you or others checked to see if any other circuit is tapped into your lighting circuit, that could account for a volt drop on start up of the other load.

 

[dean7828]

Who will be the first ummmm?

 

[dean7828]

No not yet that's one to try, just bit tricky as its a bank and the lights are in a banking hall

 

[ruston]

If it affects more than one fitting it does point to a supply problem or something stealing it's thunder.

Or faulty switching even.

 

[dean7828]

Edf has been out twice they say every think is fine, I'm now going to set up an r1+rn ill let you know the results

 

[dean7828]

Also by passed all switch gear and contactors

 

[ruston]

Points to a local supply problem then in my opinion. How many lamps are affected and are they all the same type?

 

[dean7828]

Yes all lights and lamps are the same and they all seem to be effected, supply voltage to eart and neutral both remain the same bit of a head scratcher I'd hate to walk away without an answer

 

[Guest111]

Is the load balanced across all 3 phases,or just on 1 phase?If just on 1 my money would be on a loose live or neutral at the start of the run,based on the fact that its still doing it with switcing bypassed.If balanced across 3 phases then possibly a loose neutral if the neutral is common to all lights.

 

[dean7828]

Live feed for the lighting board coms off a lage swithch isolator then onto a 100A catrage fuese then straight into the lighting board, lighting circuits consist of 4 indervidual circuits fed from that board, which is fairly new, trouble is the new lighting board is old colours and the new board is new so must be junctioned somwhere feel like I'm ****ing in the wind

 

[Engineer54]

If the lighting for the main banking hall is on a contactor, it may be well worth checking the contact tips for for burning and/or wear. I've experienced similar problems with this, on a few occasions with large inductive lighting loads...

Also, if you have tried a monitoring device on the incoming supply with no abnormalities showing up, try positioning the device on the load side of lighting circuit(s) directly after whatever method of switching is used....

 

[dean7828]

That could well be worth a punt

 

[MarkieSparkie]

Also by passed all switch gear and contactors

Although this aids testing, it may mask the fault if it's actually caused by worn or burnt contacts. My money would be on this being the likely cause due to switching the reactive load, particularly if all the lamps are on one circuit (originally designed for incandescent lamps) and snubbers have not been used to protect the contacts.

 

[grantr37]

could be an occasional supply frequency drop or distortion that affects the lighting, this could be caused by a heating or Air conditioning system connected to the building's main incoming supply via another distribution board elsewhere, knocking off the quality of the mains supply reaching your lighting network, I would think that its something like this, does it only happen during summer or both in summer and winter?...something is dropping the voltage on one (or all) of the phases and affecting the phase that you are using as lighting power.....a correction unit/cabinet could solve this...

 

[Brightspark2]

Had a similar problem before where low bay lighting would go off intermittently, then because there hot would take a while to re ignite.

Tracked the problem down to a large compacting machine that wasn't on the same DB but was on the same sub main bus bars, when the machine started it would cause a dip in the supply which was below the operating voltage of the fittings and hence them going off.

New supply from the mains to the lighting DB and problem solved...

Sent from my Xperia S using next doors WIFI.

 

[dean7828]

there is 4 ac units supplied from the same board as the lighting i tried switching off the ac units and turning them on and putting them all on test mode to insure full capacity and no noticeable dimming took effect about 20 mins later the lights started to dip, what sort of correction unit have you in mind? transient correction unit or harmonics?

 

[telectrix]

the first priority, as it's a bank, is to secure a huge loan at 0.5%, then consider looking at the fault.

 

[Guest55]

if its been going on for 2 years then the bank mustnt be that bothered otherwise they'd have just swopped all the lights over for a different type.
not exactly sort of cash are they lol.

 

[snowhead]

Lights all on the same phase on 1 board?

What else is on that 3ph board, are those the other circuits that were turned off?

What's the voltage at the board and at the lights at the time they dim, can't be 237v, that must be when they are O.K.?

Waste of time monitoring, I've tried that a few times and never got a result, you need a really high sample rate to catch anything.

It's a loose neutral to the 3ph board, but no-one's found it yet.