I am using a multi-pair wire and I am sending a 4-20 mA signal as well as an 110 digital input signal to a PLC. Thanks
2007-07-20 05:05:19 · 5 answers · asked by Frank 1 in Science & Mathematics ➔ Engineering
From a product and electrical safety standpoint, I would not recommened sending both signals down a single multipair cable. I would suggest a seperate cable for each signal.
24V is not considered a hazardous voltage so any product powered from 24V signal has been designed assuming minimal threat if a operator or service person has access to that voltage.
110V on the other hand, is a hazardous voltage often supplied by a battery source which may or may not be current limited. Should a short result between the 24V and 110V the end product may not provide adequate protection to a user, or service person. Or the device may catch fire under fault.
Crosstalk is frequency dependant not voltage dependant, but if high frequencies are involved, shielding the cables will likely be required.
2007-07-20 05:31:58 · answer #1 · answered by Anonymous · 0⤊ 0⤋
I would not but most of the time the shielding will let you get away with it. It depends on the length of the run as well a long run means more chances for trouble. I had trouble once in a cable tray where the AC was feeding a cheap DC motor control. The temperature gage was jumping just enough to cause some process problems. Another problem I had is when a wire got hot and melted the low voltage wire to the high voltage wire. It blew the tar out of the input card.
2007-07-20 12:25:05 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The National Electrical Code in the United States says that wires in the same conduit must have the same temperature and voltage rating. So it would be a violation to have a 300 V rated cable and a 600 V rated cable in the same conduit. Other than that, if signal interference isn't a problem, then its OK.
2007-07-20 13:24:10 · answer #3 · answered by In-Phase E 1 · 0⤊ 0⤋
It is never recommended.
If the 4-20 cable is shielded and you are doing it in your home where no one will see it you might get away with it from a signal-noise point of view.
Commercially it would not be accepted and mixing the high and low voltage would violate even the residential Code for sure.
2007-07-20 12:24:44 · answer #4 · answered by Rich Z 7 · 0⤊ 0⤋
With the disparity in voltage levels you may have an issue with the 110 interfering with (cross talk) the 24 v. I would run them in the same conduit as long as one of the signals is carried by a shielded cable.
2007-07-20 12:11:52 · answer #5 · answered by Tom H 4 · 0⤊ 1⤋