Installation Problem In Service Garage

[walkabouttv 0]

G'day Guys

This is my first post, just discovered the site...very imformative

I did a 5 analogue infared camera install in to a car service garage workshop 6 months ago.

It is over cat5, using seperate cables for each camera, the longest 90 metres.

I keep losing video on the cameras.

I have changed the Blauns (both ends), I have used a combined 4 channel unit which supplies power and video on 4 of them, changed cameras, changed power supplies, cut off the cat5 plugs, re-pluged using a different brand.

I seem to have them all running ,then one fails, sometimes I just unplug the camera from the blaun (DVR end) and re-plug and it comes alive, other times turning the power supply on/off works.

It's not always the same camera.

I'm about to now put in a central power supply unit, thinking maybe the power is not enough.

I have done 12+ installations in the past no problems.

There is a lot of power running through the building, close (12") to my cameras and cat5 cables, 3 pahse, electric car charging cables etc.

The camera's 1-4 are the same camera 5 is different, they are numbered 1 closest - 5 farest camera 3 & 4 had waving lines occasionally, I fitted suppresors and the fixed that problem.

Does anybody have an idea what I have done wrong?

Thanks

Mark

[Soundy 1]

How many pairs of the Cat5 are used for power, and how much current do the cameras draw? Sounds typical of voltage loss caused by too much current draw over too-small wire. If that's the case, replacing the power supply won't fix it, as it's not a matter of how much current is available at the source.

[walkabouttv 0]

G'day Soundy

The cameras draw 2.5 watts each.

As far as I can tell one pair.

Thanks for a fast response

Mark

[Soundy 1]

The cameras draw 2.5 watts each

That must be with the IR off - that's only 200mA. Most IR cameras will pull anywhere between 500mA to a full amp when the IRs come on.

 

As far as I can tell one pair.

That's likely your problem. Assuming a camera pulls 500mA with IR on, at 90m (about 300'), you're going to see a loss of about 3.8V(!!!), so assuming a regulated 12V supply, the camera is only getting 8.2V. Even at 200mA, that's 1.5V loss, which may be borderline.

 

Step it up to use two pairs for power, and your loss at 90m and 200mA is only 0.7V... 3 pairs, and the loss is only 0.3V.

[walkabouttv 0]

Thanks Soundy,

I will try it on 3 twisted pair, so I do not have to buy new blauns I will put on new cat plugs at the camera end using just the video pair, then splice off 3 pairs and attach a power plug.

As a future idea could I put 24vac up a cat5, then put a 24vac>12dc converter on the camera end?

Thanks

Mark

[Soundy 1]

You could do that, but using multiple pairs should alleviate the problem. Using better cameras would as well, addressing both this issue AND the problem with the waving lines (sounds like a ground loop, common when using low-grade cameras with baluns and a shared power supply).

[walkabouttv 0]

Soundy

When you say shared powered supply, do you mean a regulated standalone supply split to different cameras or a dedicated supply like this:

 

http://www.ddstrade.co.uk/12vdc-central-distribution-power-supplies.html

 

Would this be a better option for powering multiple cameras from one location in the future?

Mark

[Soundy 1]

Soundy

When you say shared powered supply, do you mean a regulated standalone supply split to different cameras or a dedicated supply like this:

Either - both are powering all the cameras off a common power and ground rail. Having all the camera power grounds tied together like that can create ground loop problems in certain circumstances.

 

Would this be a better option for powering multiple cameras from one location in the future?

Mark

It makes for a cleaner install... that's about it.

 

Read this thread for more info on the ground loop issue: viewtopic.php?f=6&t=30871&hilit=+ground+loop