Maximum Distance For A Psu From A Speed Dome?

[dsw]

Sorry to be asking another question but we are currently quoting a job with 2 ptz speed domes and 2 body cameras. Bodys are 24v and will be powered from central psu. We would like to power the ptz's from the same source but i know that the distance to the ptz to psu could be an issue as they are more sensitive to voltage loss. PTZ's would be around 50-80meters max from psu. This is probably too far but is there a recommended distance from psu with ptz's. It would save us having to get a qualified spark to put fused spurs in but will have to do that if its the only option.

Paul

[esp-protocol]

You need to double check the IEE regs for exact figures, and installation factors etc, but as a worst case, if you assume the mv/A/m for 1.5mm cable to be 30mv, the cable length to be 100 m, you need to know the maximum current draw from both ptz's.

Then basically, 0.030(mv/A/m) X 100 (m) X Current (ptz1 + ptz2) = volt drop

So if each PTZ draws .75 amps then .03 X 100 X 1.5 = 4.5 volts

This is a worst case rule of thumb assuming the whole load is at the end of the cable.

If you use 2.5mm cable, the mv factor is around 20mv/A/m.

[ian.cant]

I do a lot of CCTV work on a large supermarket where the 24 ac domes are powered from one source. I am supplied with .75mm 3 core flex, some runs are very short some are way over 100mtrs, never had a problem yet!

[Guest Trulloman]

Dont forget to allow for when the heaters kicks in, on a long run it could take approx 5-6v drop.