Event Driven Interferance - Help !!

[TJCCTV 0]

I have a video problem that I haven't seen the answer to yet.

 

Doesn't appear to be a ground loop issue. Am I correct that a ground loop

problem should be pretty much consistant 24/7?

 

This problem occurs at specific times of the day when specific heavy

industrial equipment is turned on / off.

 

System specs: 12v. Some cameras are powered through box power

supply.

 

Affects three cameras which have separate video cabling (cat5e/baluns),

and due to their distance from the power supply box, are running off their

separate transformers. All three transformers (due to their location), are

plugged into the same power plug-in.

 

1. After exhaustive testing and analysis of video I have narrowed down

that the three experience the interference and clarity in unison.

 

2. The events occur when an employee starts up / turns off a specific

piece of heavy industrial equipment that is crucial to the business, in an

adjoining section of the building.

 

The interference clears after the piece of equipment has had time to "wind

down" and not immediately when it is turned off, if that helps.

 

Any ideas on this one? I'm not having much luck yet.....

 

Thanks!

 

PS. Please don't post any images I may have sent. I will PM them

but can't have them floating on the internet or I can have a really

upset client on my hands to deal with. Everyone's help is truly

appreciated and welcomed.

Edited January 9, 2010 by Guest

[Soundy 1]

I have a video problem that I haven't seen the answer to yet.

 

Doesn't appear to be a ground loop issue. Am I correct that a ground loop

problem should be pretty much consistant 24/7?

 

Generally, yes, but not always.

 

This problem occurs at specific times of the day when specific heavy industrial equipment is turned on / off.

 

It COULD still be a ground loop, depending on how that equipment is connected... but it's more likely EMI, or induced noise.

 

It's often a lot easier to tell if we can see images of it, though.

 

System specs: 12v. Some cameras are powered through box power supply.

 

Affects three cameras which have separate video cabling (cat5e/baluns),

and due to their distance from the power supply box, are running off their

separate transformers. All three transformers (due to their location), are

plugged into the same power plug-in.

 

1. After exhaustive testing and analysis of video I have narrowed down

that the three experience the interference and clarity in unison.

 

2. The events occur when an employee starts up / turns off a specific

piece of heavy industrial equipment that is crucial to the business, in an

adjoining section of the building.

 

The interference clears after the piece of equipment has had time to "wind

down" and not immediately when it is turned off, if that helps.

 

Any ideas on this one? I'm not having much luck yet.....

 

Thanks!

 

That last bit does help - it definitely sounds like EMI being produced by this equipment, as any motor will continue to generate a current after being turned off, as long as it's turning.

 

I'd check whether the cameras are plugged into the same circuit as the equipment; it's quite likely the noise is being thrown back down the building's wiring. Also, have an electrician test both the equipment's and the outlet's wiring for proper neutral and grounding - normally, the neutral and the ground should be at the same potential, and if there's a difference, it can lead to increased noise, and yes, even a ground loop. In fact, I'd have him test the outlet that the DVR is plugged into as well.

Edited December 28, 2009 by Guest

[oldtimer 0]

It looks as if your power supply doesn't have good regulation. I believe you are running 12v DC. If this isn't the case. You mention balums. Try reversing the leads at one end. Getting back to the power supply. Check the input voltage and then leave your meter hooked up and turn on this piece of equipment that is causing problems. and see if you get a voltage drop. Speaking of this equipment, is it possible it is sending some RF in the area. Again I have seen ground loops through some of us for a loop ourselves. I stay away from balums and twisted pair if I can. Good quality coax is the best. Always use copper clad only.

[Soundy 1]

TJCCTV sent me a PM with links to screenshots... hope he doesn't mind if I repost the PM here, so others get a better idea of what's going on:

The interference occurs on three of sixteen cameras which are using their own power transformers but are plugged into the same source outlet. The others that are always clear are either through a common power box or from power supplied directly at the power poles. The three seem to experience the interference in unison when a specific event occurs. Employee turns on or turns off a certain piece of industrial equipment (which can't be replaced).

 

Color Clear (No Interference)

{photos removed by request}

 

Color With Interference (note the arrows)

{photos removed by request}

 

Infrared Clear

{photos removed by request}

 

Infrared With Interference

{photos removed by request}

 

Definitely looks like some low-level induced noise. As I suggested before, this is something you probably want to get a qualified electrician involved in (preferably one who's very experienced with industrial systems, particularly three-phase systems). Have him confirm proper wiring and grounding of the equipment in question, and have him check whether the camera power is on the same circuit leg as the equipment (unless this equipment is three-phase, then it's pretty much guaranteed to be sharing a leg).

 

He should also check for proper wiring of the outlet the camera power is on - specifically, he'll want to check for proper ground AND neutral wiring. Even something like a corroded connection could lead to a ground loop that can allow or even exacerbate the induction of such noise.

Edited January 9, 2010 by Guest

[oldtimer 0]

Switch the effected cameras over to the power supply. I think those transformers on a power strip may be the problem. Individual power supplies (tramsformers) can cause a lot of goofy things.

[cglaeser 0]

Switch the effected cameras over to the power supply. I think those transformers on a power strip may be the problem. Individual power supplies (tramsformers) can cause a lot of goofy things.

 

Agreed. If the distance is too far or too difficult to run to the existing power supply, you can replace the three transformers with an Altronix (or similar) for modest cost.

 

Best,

Christopher