480V 3phase interference with VFD control?

[Regg]

We are converting 32 nonspeed controlled conveyors to VFD Control. We're installing two cabinents which contain 16 VFD units each. We are debating whether to run all the control loops together seperated from the 480 line/load conductors. They are a 12V pulsed signal and go down to a set of NO points in the Buckets from where of course the 480V line/load conductors will pass through too so there will be some chance to create a little space between the two once they are inside the motor contro center. Has anybody done a similar project? The cabinent wiring would look much cleaner if the control wires were run with the 480V and this what the tech wants. There will be two 1 1/4" EMT conduits for each cabinent. I believe seperation is best since the conductors are #18 single stranded MTW conductors. Any opinions? I'll probably call the manufacturer in the next few days and report back their ideas too. Thanks!

 

[gar]

080507-1842 EST

Regg:

I would never run low voltage signal wires with power wiring.

What is a 12 V pulsed signal? What is the source and destination? Is the source isolated from common? Is the source a balanced line driver? What common mode voltage can it tolerate? What is the pulse rate and duration of the pulse? Is this from an encoder? Or is it just a limit switch signal? How much noise can you inject without causing a malfunction? Are you using twisted pairs? And shielding? How is the shield terminated and where?

What are normally open points? What is a bucket?

What does #18 single stranded mean? Does this mean you are using a stranded #18 wire and a single wire for each signal? This implies no twisted pair. Is there another single wire run parallel and not twisted to the signal wire that provides the reference line and is one common line common to all the signal lines?

Note: if you used a balanced driver and receiver with good common mode rejection and twisted the signal pair you would get fairly good noise immunity, and shielding would further help.

We need more information.

.

 

[Lxnxjxhx]

If the VFD people have foreseen this usage, they may have installed 60 Hz notch filters, in addition to differential-mode drivers and receivers.

Ask. They want their stuff to be versatile and to work.

 

[weressl]

We are converting 32 nonspeed controlled conveyors to VFD Control. We're installing two cabinents which contain 16 VFD units each. We are debating whether to run all the control loops together seperated from the 480 line/load conductors. They are a 12V pulsed signal and go down to a set of NO points in the Buckets from where of course the 480V line/load conductors will pass through too so there will be some chance to create a little space between the two once they are inside the motor contro center. Has anybody done a similar project? The cabinent wiring would look much cleaner if the control wires were run with the 480V and this what the tech wants. There will be two 1 1/4" EMT conduits for each cabinent. I believe seperation is best since the conductors are #18 single stranded MTW conductors. Any opinions? I'll probably call the manufacturer in the next few days and report back their ideas too. Thanks!

Installing the ASD's in a common cabinet can cause control interference between the drives. Check with the manufacturer. The design should also concern itself with appropriate heat removal, thermal design.

The ASD control wiring often uses a power source supplied by teh drive itself and required to be run in a shielded cable, separately from the power cables, in its own conduit or raceway.