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Active Contributor

Join Date: Dec 2016
Posts: 11

Instrumentation Cable

12/28/2017 5:41 AM

I have a damper actuator which has a power supply requirement of 24V AC, and requires (0-10V)- 1 wire (AO) for modulating control and provides (0-10V)- 1 wire (AI).

Can I provide 2 pair cables for this Instrument.
a) First pair - 24V AC
b) Second pair (0-10V) - 1 wire for AO and another wire for AI (or) do I need to provide separate pairs for both AI and AO.

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Power-User

Join Date: Jul 2010
Posts: 127
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#1

Re: Instrumentation Cable

12/28/2017 10:21 AM

Any Circuit needs 2 paths/conductors/wires between the power and the load.

Somewhere there is a return/(-)/common for each of the analog signals.

You need 2 wires for the AO and 2 wires for the AI, even if they share a common return.

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Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#2

Re: Instrumentation Cable

12/28/2017 10:54 AM

The original equipment manufacturer's instruction leaflet that came with it will say. If it is not to hand, telephone the manufacturer to obtain a replacement.

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Guru
Engineering Fields - Electrical Engineering - Been there, done that, still doing it. Engineering Fields - Control Engineering - New Member

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#3

Re: Instrumentation Cable

12/28/2017 12:29 PM

I've long admired the cleverness and simplicity of Dallas Semiconductor's 1-Wire digital communication. I still dislike the misleading, misnomer name. What you have is obviously not strictly a 1-wire device since it requires a separate power supply and involves two analog signals. Refer to the manufacturer's user manual.

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Guru

Join Date: Mar 2007
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#4

Re: Instrumentation Cable

12/28/2017 3:05 PM
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Active Contributor

Join Date: Mar 2017
Posts: 12
#5

Re: Instrumentation Cable

12/29/2017 1:55 AM

The original equipment manufacturer's instruction leaflet that came with it will say.

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Power-User

Join Date: Jun 2012
Posts: 110
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#6

Re: Instrumentation Cable

12/29/2017 5:02 AM

If both (a)common of the analog AO and AI circuits and (b)neutral of the 24 VAC supply are connected together, then you can provide two 2-pair cables as you describe.

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Member

Join Date: Feb 2017
Posts: 5
Good Answers: 1
#7

Re: Instrumentation Cable

12/29/2017 8:40 AM

For instrumentation control like you describe, one cable is sufficient, having 4 conductors (twisted pairs), 24AWG. One pair for 24VDC, the other for AO/A1 as you implied. Belden, Alpha, and others make similar products. Ex. Belden 9502.

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Participant

Join Date: Sep 2017
Posts: 3
#8

Re: Instrumentation Cable

12/29/2017 1:37 PM

Consider Luminary cable!

I happen to have a sample with the following marking:

Kaf-Tech 800-757-6996

MC Luminary Multi Zone Lite

Type MC-PCS Metal-Clad Cable

part number 18LC-44-501

12-3/16-2 (2TPJ)

Luminary cable is now commonly used where 0-10VDC lighting controls are needed in addition to AC power.

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Participant

Join Date: Jan 2018
Posts: 1
#9

Re: Instrumentation Cable

01/01/2018 11:50 AM

It depends on noise and how the cable is structured. Its the cable under ground coming to the actuator or is conduit running up to it in a non class or zone.

Either way noise could be an issue. Noisy cable can take away from a perfectly calibrated instrument. 24 VAC is one cable and signal control and feedback is can be another cable. If there is not enough of room for a two cable assembly, then consider using one cable for both. Twisted pair for signal conditional side.

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