Motor control cable lenght
Motor control cable lenght
(OP)
HI,
I have an application where the start-stop buttons for a motor will be 4000 feet from the starter. We planned to install relays in the starters that will be driven by the buttons. We will use #14 AWG wiring (Teck armored cable) for this application. Voltage drop is ok to drive the relays.
Should I be concerned with any other phenomenon that could trigger these relays because of the cable length ?
Thanks,
Michel
I have an application where the start-stop buttons for a motor will be 4000 feet from the starter. We planned to install relays in the starters that will be driven by the buttons. We will use #14 AWG wiring (Teck armored cable) for this application. Voltage drop is ok to drive the relays.
Should I be concerned with any other phenomenon that could trigger these relays because of the cable length ?
Thanks,
Michel





RE: Motor control cable lenght
There have been a few earlier discussion about this in this forum. Try doing a search on control circuit distance, or something similar - maybe in the Power engineering forum as well. Anything over about 1000 feet will be a problem.
You can do it with a dc control circuit.
RE: Motor control cable lenght
RE: Motor control cable lenght
Square D has a paper that gives maximum recommended circuit lengths at different ac control voltages. They are surprisingly short.
Google up Square D Data Bulletin M-379F or try this:
http://eca
RE: Motor control cable lenght
But we use Teck armored cable with explosion proof sealed connectors at both ends. The risk of water entering the cable is almost nil. I wonder what the values for distances for shunt capacitance be, considering a dry cable....
RE: Motor control cable lenght
A dry cable will work better, but there is still capacitance.
RE: Motor control cable lenght
Keith Cress
kcress - http://www.flaminsystems.com
RE: Motor control cable lenght
If your controlling something that far away, you need to have a power drop, run a comm cable between the plc where the pushbuttons are tied to and the motor area. Even the comm cable would have to have repeaters due to the distance.
Why 500 ft? Most reasonable priced wire is in 500ft runs. Good luck getting a manufacturer to produce a 4000ft spool.
RE: Motor control cable lenght
RE: Motor control cable lenght
At that distance though, I'd be really tempted to try and use DC control. If the motor starter needs to be AC control in the cabinet, you could use a small DC power supply and an interposing relay for your control circuit.
A 4000' length of TECK should be pretty easy to find - we order up 5000' reels on a semi-regular basis for our site.