AC & DC in 1 Cable Ducting

It depends upon a lot of things that have not been revealed.

http://en.wikipedia.org/wiki/Crosstalk_(electronics)

However, the following have been successful:

• Crossing heavy power and light signal cables at right-angles.
• Using current for signal transmission rather than voltage. 4-20mA DC is an industry standard that is largely immune to cross-talk from high power AC cables nearby.
• Shielding within the cables' construction.
• Maintaining segregation between different types of cables where they run in parallel.
• Railway track circuits for detecting trains that use AC in DC-power districts and DC in AC-power districts, despite using one of the running rails a common return for both power and detection.
• Use of fibre-optics for data signal transmission.

so there's plenty of opportunity for some bedtime reading on the subject.

2) Is there any interruption interaction ?! between AC and DC current flow?

In what context?

...other than the examples given in #1↑, of course?

Exacturemont! Just tried to untangle the wording of OP - but seems I tangle myself up in words . . .

Yes.

and of course the cable insulation on the 12 to 24 V cable should be rated to the highest voltage present in the enclosure (unless they are segregated through the entire run)

1) What will happen if i put AC cable (110 or 240) and DC cable (12 or 24) in one cable ducting?

Nothing under normal circumstances.

2) Is there any interaction between AC and DC current flow?

With a sensitive instrument you would probably be able to detect the presence of the AC signals on the DC wires, but, there would be no discernible effect on any equipment powered by the DC.

Inductive interference is caused by the magnetic flux generated by electrical currents

inducing voltages in nearby conductors.

Countermeasures

•Do not run power cables close to control or signal cables

•Use either segmented trunking or different cable tray sections for power and control

•Use twisted pair cables for connection of devices requiring supply and return

connection

•Use shielded signal cables and connect the shield to earth at both ends.

Capacitive interference can occur if signal cables with different voltage levels are

run closely together. It can also be caused by power cables running close to signal

lines.

Countermeasures

• separate signal cables with differing voltage levels;

• do not run signal cables close to power cables;

• if possible use shielded cable for vulnerable signal lines.

Electromagnetic interference can induce both currents and voltages in signal cables.

It really depends on the application. Can you provide much more detail including ducting size, type of cables used and what signals are on the DC cables.

What do your local electrical standards say?

1,. YES 2,. YES.

The question is equivalent: the ship is this high, that wide. How fast is it moving?

Well, it is a nonsense without the missing parts.

So, as to put in some sense, I presume household wiring for AC, a modest solar cell DC from the roof enroute to a battery bank.

I presume also, that the code permits such colocation.

I would put in twisted pairs for both the AC and DC, and have a cold brewsky without any second thought.

Now, if and when the insulation between the two sets fail, all the bets are off.

I guess, that is the answer you were looking for.

Use 3 compartment duct(metal or metal coated plastic)one for power,one for telephone and one for data.Verify from manufacturer whether it is ok.

If you are doing it for a customer you no doubt are violating the customer's electrical specifications. This is a universal no-no in electrical specifications. If for the plant where you work, again there should be a specification or directive against this. For yourself - no real problem, assuming proper insulation ratings and such. Now if the 240VAC mentioned in your post is coming from a VFD, and the 24VDC is a 4-20ma signal, then we have a real potential for a noise problem here.

Only DC I really wouldn't put beside normal AC is an RTD signal.

I know this is not really conduit, but the same idea - We put AC as high as 575V in a small (36" x 30" x 12") motor control panel with 24VDC for control signals all the time with no interference problems. We usually try to keep high voltage VFD's seperate from 24VDC signals as much as possible, but I've seen customer's require us to put 480VAC VFD's up to 20HP rating in the same small control panel as a PLC - and of course the conductors must run parallel in some wiring ducts. Shielding is very important here.

A bit off the subject - Only real noise problem I've seen in 25 years of building automated process skids was with a Profibus signal and a VFD driven motor. Grounding of shields is very very critical here.

If the cables will have on - off or power applications you could do it, if they are modulating signals then it is not advisable, even if the 12 and 24V signals are in shielded cables.

Personally, if there were any way to avoid it, I wouldn't do it.

1) The AC cables will probably induce noise signals onto the DC cables. Whether that's tolerable or not depends upon what those cables are connected to. But it's not advised (see other posts for details).

2) It is possible that signals induced by the AC cables onto the DC cables could produce noise spikes that could "interrupt" the DC current flow. Actually, the "interruption" or interference would mainly be seen at the input stages of equipment connected to those DC cables - they saturate the DC inputs, disrupting the work performed by the DC equipment.

By "ducting" do you mean installing both types of cabling into the same metallic conduits or raceways? In the U.S. the National Electrical Code (NEC) doesn't allow that not only for interference reasons but also for safety reasons. It does allow an exception if you have a continuous metal separator (wall) between the AC and DC cablings. So you could run a small conduit (containing one cabling type) inside a large conduit (with the other cabling) but it could be impractical / a last resort. Try to use separate conduits.

Your "ducting" reference reminds me of a bid we lost. The customer was concerned that we would have to breach several building firewalls to run cables across his building, and that he had asbestos in those ceilings. Our salesman suggested that we'd run our cables inside the existing HVAC ductwork - not only violating the NEC but also some building codes!