what will be effect on system if 240v ac and 24v dc cables will run in same cond

Diwan, the specifics and detail in your question is admirable, in that detail is sadly missing from most questions lately. Thank you.

However, it seems to be detailed as part of a homework assignment. Please let us know if this is the case, and we will assist in an appropriate manner.

For now I can state that the issues involved when mixing different voltages, and mixing electric and different communication conductors together in a raceway or close proximity involve, but are not limited to:

1. Magnetic interference and induction issues, and

2. Safety issues (shorts, crossed wires, etc.)

As for the code requirements you seek, they will be dictated by the region of the earth and the standards enforced in that region. The engineering considerations will be dependent on a myriad of details about the insulations, voltages, armors, grounding methods etc.

You would do well to lay out a matrix of the properties of each type of cable and of what it conducts, then determine the possible inter-actions, and correlate them with the details you have provided lengthwise. Some will not matter, some will have great effects in certain proximity.

Google and other search sites will prove most useful to you in this endeavor, as I assume it has occurred to you to search this sites previous threads where most of your queries have already been answered at length.

Regards, CJM

The mutual inductance may provide a bit of AC voltage in the DC line.

the 24V DC is for what purpose ? our place it is for the handlamps etc, in that case no problem , but ensure that there is no chance of the two conductors coming in contact due to some insulation damage etc. If you have proper grounded armour, you can avoid the normal interference and safety aspects also especially if it is in the DC line.

Instrument and power cable can never be in the same tray, The interference despite the shielding will affect both ends of the instrumentation and may also damage them. Okease note that in many casem especially in digitals, you may not have that effective filter.

Fiberoptic cables can run in the same trench. This is the only one that can run.

Your sentence is too long, Could have split it into a) b) c) but broadly the above three are your sub-categories. Length immaterial.

a) Power and Service Voltage (with proper safety precaution)

b) Power and c&I stritcly no

c) Power and fiber optics - no problem, except if you heve to change the f/o cable for any reason, you may have to turn the power off.

Mr Khan

1.For Power and control ( signal cable ) distance you can keep 300mm. This distance avoid the distorsion noise in the signal in long time

2. For 230VAC & 24VDC in same conduit it will not effect the on the system for short distance of conduit . If you have long conduit for the same power it will craet induction effect but you can avoid by good grounding of conduit

3. Communication cable like LAW ,WAN, Profibus , ethernet etc avoid to run with power cables it will creat noise in the commnication and poor signals. You have keep distance of 100mm atleat if you can not avoid

4. Power and controls cable alway keep in dirrenet tray and distance should be 300mm.

Regards

SALIM PATHAN

M/S HINADLCO IND LTD

,KHNAVEL , SILVASSA, UT OF D&NH

INDIA

As far as electrical inter-action, it all depends on what you do with these voltages and their circuit impedances.

If all you do is activate relays (low impedances), mixing low voltage circuits (< 600V) will not have any consequences. 4-20mA is quite immune to pick-up unless you have hundreds of meters of parallel coupling.

If you are talking about communication or 0-10V analog signals with relatively high impedances, long coupling (meters) should be avoided.

The type of cables used also makes a difference. A shielded twisted pair cable is not very sensitive to noise coupling. Much less than straight parallel wires pulled in the conduit.

Finally, optical fibre are totally immune but their power supplies wires are not.

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But, for maintenance purpose, it is safer to keep them separate and color coded to prevent mistakes when troubleshooting equipments.

From a purely electrical code perspective(NEC) all conductors' insulation voltage rating must be equal to the highest voltage expected on any of the conductors to be safety run in the same raceway or conduit. From an engineering perspective,it is not wise to mix low voltage digital signal wires with A/C conductors because of possible noise problems. Same with analog signals. Fiber optics don't care,insofar as interference, but best practice is to keep them separate to avoid physical damage to the fiber optic cable during installation.Also fiber optic cable cannot tolerate the same sharp bends as electrical wiring.The RTD cables are especially sensitive to induced noise, since the input goes directly to an op-amp. Separate your digital,analog,fiber and power signals in separate conduits/trays.When securing fiber is required, use the Velcro type cable ties, not the standard hard plastic type. Do it right, and you only have to do it once.---------------------------------------------------------------------------HTRN------------------------------------------

Hi all,

Simply put - do not run instrumentation cables with electrical cables. If you must run them in parallel keep a distance of at least 200mm between them.

The electrical AC cable will "induce" spurious signals in the instrument DC line. The signals that would be especially susceptible to this are RTD, thermocouple and voltage signals (0-10V for example).

For the same reason - keep your communication cables away from the electrical cables. The will create havoc. You should also make sure your instrument cables are individually and overall screened.

Regards,

Craig

There are wireways that have internal divisions for separation of high voltage AC and 24Vdc control voltages. It would also to be wise to use good shielded cables and make sure that the shield is connected in a star pattern and not daisy chained. You do not want any ground loops in the system. There are many types of shielding. If you use 6 wire cable for an encoder for instance you should use triplex shielding where each individual pair and the over bundle are all shielded. Any close AC Motor Armature wiring should also be shielded to keep the noise inside the cable and not let it out. Shielding can be crucial so make sure it is done correctly.

Sir,

As the others have consistantly said, most of the possible mixed cable types are very poor design. In the USA, the National Electrical Code is the nearly universal governing set of rules. It gives some overall guidelines that are probably similar to the codes in your area:

1) Power, control and signaling cables can occupy the same conduit if they are for the same piece of equipment and are all insulated to the highest voltage present.

2) The circuits for control and signaling are usually classified as power-limited circuits that therefore have safety rules directed towards limiting the effects of shorts or equipment mal-function. If mixed in conduits with cables that are not power-limited, it is quite possible that you will void the laboratory tests and safety approvals for the equipment they connect to.

Beyond this, you need to look at the possibility of noise interference. Even fairly short parallel runs can have electronic noise induced from power into the signal/control cables, or between different signal/control cables. Depending on the signal or control type and the sensitivity you are needing, this induced noise may be totally unimportant or may be totallty destructive.

Generally, good answers to your questions can come from the suppliers of the equipment, intheir installation instructions. Mixed cable types is usually considered to be poor design, the evidence of a person who is not worth keeping.

--JMM

A1) The only one in the list that is of any worry is the <...415vac cables and digital/communication cables in same pvc conduit 20m....> as there is a risk of bcrupting the communications. Everything else should survive the experience.

A2) Declined. End-client standards are not available to read here and therefore cannot be expressed.