CONTROL CABLE & POWER CABLE...WHAT'S THE DIFFERENCE...for your philippine electrical concerns...needs...installation...orders...safeelectrical2013@gmail.com

Difference Between Control And Power Cable 05/19/2007 8:16 AM

What is the difference between control cables and power cables.how will we differenciate this two by application wise in industry.what is the maximum size of the control and power cable. PL CLEAR IT

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Anonymous Poster	#1  Re: Difference Between Control And Power Cable 05/19/2007 9:51 PM
	It depends on the currents to be used in each case. Control currents are usually less than power currents. Sometimes a minumum conductor size will be specified for control cables, which is important for the mechanical strength of the cable and based upon standards that have been gained from experience and best practice. In many cases the control cables could carry currents many times normal without damage; were the cable to be smaller then it could get damaged by external actions and require frequent replacement. Power cables are sized according to their current-carrying requirements, length, routing and ambient temperatures, among other factors. Usually the principal concern is the size of the conductors, so as to keep the value of the cable as low as is consistent with safe operation. Power cables can be larger than control cables or, for small loads for instance, they can be the same size. Cables are sized according to regulations.http://www.iee.org/Publish/WireRegs/ is valid for the UK. Cable sizing should be done by a qualified Electrical Engineer in all but the simplest cases.
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CNCdoc Commentator Join Date: Apr 2006 Posts: 60	#7 In reply to #1  Re: Difference Between Control And Power Cable 05/20/2007 9:58 AM
	The voltage plays a large part in the size of the conductor as does the phase of the power supply. 480 Volts AC 3 phase will allow for smaller diameter (gauge) than 240 VAC 3 Phase or single phase. It is easier to get more power from a smaller motor (than a larger motor) and be more efficient using 3 phase power than single phase or DC. The wires are smaller as well and are either switched on and off by a relay or controlled by an Inverter, motor drive, servo drive or frequency drive depending on the type of motor and it's appilication. Often power wires are run in the same conduit or tracks as control wires with some precautions as to RF interference as is noted below. Control cables in many machines and automation modules use different size wire, but it is usually in 4 to 24 conductor and is usually 18 to 26 gauge wire, if it moves (as in a track) it is stranded wire. Most machinery use stranded wire and not solid conductor in control and power cables. The information carried dictates the size and type of cable. High speed digital data can be carried over fiber optic (from cpu/pc to nc or sub-system I/O or multi motor drives) or serial cables with "twisted pair" wiring. Digital signals are high/low where high is about 5 VDC and Low is about 1/2 of a volt. Other control cables carry 24 VAC or VDC or 110 VAC from an I/O control for output signals to other devices such as solenoid valves. Others are part of a circuit that will stop the machine (ESTOP) when certain conditions are met; Limit switches, low oil, low air, and any other condition fed to the cpu from it's sub-systems which monitor servo, spindle and other motor conditions and output an alarm which will stop automatic machine operation. The rest of the control cable infromation is usually position information carried to the CPU by encoders which use 5 to 24 VAC depending on manufacturer and often has it's own dedicated cable which includes power. Control Cables carry information as inputs and outputs and utilize smaller voltage. They may be the same size physically as some power cables. Power Cables carry power to a motor or other device such as a heating coil. The size of the cable is dependant upon the application (immersion, chemicals etc), the size and type of conductor (copper, aluminum), voltage, phase, full current required and length of cable needed to reach device from power supply. The question asked is rather ambiguous, perhaps more particulars would yield a better answer.
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Anonymous Poster	#2  Re: Difference Between Control And Power Cable 05/19/2007 11:27 PM
	The difference is in what they do. Lets assume a machine runs on 120v AC; everything in the machine runs on this voltage. The power cables probably will go to some relay CONTACTS then to a motor or two and some solinoids. The control cable will go to some operator panel and to the realy COILS. The control cable will carry much less current than the power cables, but could be the same size wire as the power cables. Now lest assume a machine uses 24v AC to switch the 120v. The power wire goes to the control transformer and all the other stuff (motor, solinois). The control cable still goes to the operator pannel and stuff, but this time it is probably a smaller gague wire than before. As for how to tell the difference, if you have a schmatic, refer to it. If you don't, find out where the wires lead to and go from the examples. Every machine can be different depending on what the designers wanted to do with it.
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Andy D/PE Active Contributor Join Date: Sep 2006 Posts: 24	#3  Re: Difference Between Control And Power Cable 05/20/2007 1:33 AM
	Must be careful in some cases to keep power and control cables separate, as the induced currents could cause a problem with the controls.
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Anonymous Poster	#4 In reply to #3  Re: Difference Between Control And Power Cable 05/20/2007 2:17 AM
	This is especially true with variable frequency drives.
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Anonymous Poster	#5 In reply to #4  Re: Difference Between Control And Power Cable 05/20/2007 3:40 AM
	Often control cables will be SHIELDED, i.e. have an outer metallised sheath earthed AT ONE END ONLY. This shields from outside interference, as control currents / powers can be low interference can be a factor. All wires act as an aerial so can pick up signals.
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jstolaruk Power-User Join Date: Nov 2006 Location: SE MI USA Posts: 105	#6 In reply to #4  Re: Difference Between Control And Power Cable 05/20/2007 8:09 AM
	And servos.
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Pragmatist Power-User   Join Date: Apr 2006 Posts: 261	#8  Re: Difference Between Control And Power Cable 05/20/2007 3:03 PM
	As I believe this is your second poston the subject, even though its already been said,let's make it really clear to you. The difference is primarily in the function for which the cable is used. Wire & cable themselves are rated as to voltage, (insulation), and amperage, (size/insulation temp. rating). One chooses the wire or cable on that basis plus the number of conductors required. (Sometimes shielding comes into play for specific controls.)
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