ARAMCO STANDARD!! 2

[milgaru11]

I am an instrument engineer in SAUDI ARAMCO PROJECT.
ARAMCO requires very difficult two things to meet.
1. The maximum voltage drop shall not exceed 5%.
2. If a discrete loop length exceeds 305 meters (≈1000 feet), 120 VAC signal shall not be used due to potential capacitive (phantom voltage) or inductive coupling. In such cases, DC voltage shall be used.

Instrument are usually 24DC powered circuit with max 12AWG cable.(but normally max 14AWG, 12AWG is unusual case for us)
Some instrument power consumption 30~40W with 600~1000m. (Horn & Beacon for Gas detectors)
With these condition, 24VDC power is impossible to meet above requirement. (even manufacturer's allowable working voltage 20~27VDC cannot meet)
I think 120VAC signal to be used.

1. Anybody has experience for these things?
2. How to avoid potential capacitive or inductive coupling?
3. Phantom voltage can make work horn & beacon which has 30~40w?

 

[waross]

Run power to the horn and beacon.
Control them with a low wattage DC relay.
You may run a higher voltage (380V, 400V, 480V) and step it down with a small transformer.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

milgaru11; I'm thinking you're mixing up terms. "AC signal" is just that. It's not "power". They don't want you using 120Vac as a signal. You can have nasty problems with AC signals on long runs. But AC power has no problem with the long distance, unless of-course, you have voltage drop issues due to loading.

waross's suggestion does as I've stated by separating the power and the signal.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[marcoleer]

We use high frequency (860Hz) and voltage (190Vac) to power our offshore/marine foghorn products.
I quickly calculated (so correct me if I'm wrong) 2.5mm2 can power up to 1000m at 4% voltage loss.
The controllers are powered from 230Vac or 24Vdc power supplies, and converted to 190Vac.

 

[itsmoked]

marcoleer; You are apparently hijacking this thread which will get you few responses and confuse people. [!]Please copy this and start your own thread - then DELETE this.[/!]

Keith Cress
kcress -

http://www.flaminsystems.com

 

[marcoleer]

itsmoked; just trying to help. I just mention what I've seen that has been delivered to Aramco. If you thinks its not helpful, just ignore.

Marco van der Leer
ORGA BV -

http://www.orga.nl/remote-power