25 Year Old VS Drive System Integration Help
25 Year Old VS Drive System Integration Help
(OP)
We are in the early stages of replacing a 25 year old engineered V/S drive system. The plans are to have the new system completely engineered and installed by November of this year. In the mean time we want to start the integration of the existing drive system into our DCS system. This step starts with automatic draw control of various drive sections. Easy enough to measure the draw and input it into the DCS, hard part getting the drives to accept a signal from the DCS (Honeywell TDC3000, only knows 4-20mA).
The drive system has a master pot that determines overall line speed. This voltage is then sent to each on the drives on the machine. At each drive there is another pot that is used to bias speed off of the master speed i.e. draw control. As in most drive systems of this vintage the pot is used as a voltage divider to supply a reference to the drive. In this case the master line speed is a 0-8VDC signal that signal is then sent through a pot to common and the wiper provides the speed reference in a range of 0-4VDC.
There are many manufactures of signal isolators and converters that will change to 4-20mA to a voltage signal Moore Industries, Action Instruments, etc. These will not work in this situation because the need to used the master voltage and divide it to get the speed reference.
My question does anyone know of anyone that makes a device to pull off such a task?
Thanks for any help…!
The drive system has a master pot that determines overall line speed. This voltage is then sent to each on the drives on the machine. At each drive there is another pot that is used to bias speed off of the master speed i.e. draw control. As in most drive systems of this vintage the pot is used as a voltage divider to supply a reference to the drive. In this case the master line speed is a 0-8VDC signal that signal is then sent through a pot to common and the wiper provides the speed reference in a range of 0-4VDC.
There are many manufactures of signal isolators and converters that will change to 4-20mA to a voltage signal Moore Industries, Action Instruments, etc. These will not work in this situation because the need to used the master voltage and divide it to get the speed reference.
My question does anyone know of anyone that makes a device to pull off such a task?
Thanks for any help…!





RE: 25 Year Old VS Drive System Integration Help
Failing that, how about using a fixed resistor wired as load to the voltage signal to produce mA in series with 4-20mA device? I would think the V source would have the capability to deliver some power (milliwatts).
In fact a transducer can't get any simpler than a resistor.
R=V/I
RE: 25 Year Old VS Drive System Integration Help
RE: 25 Year Old VS Drive System Integration Help
Thanks for your replies
RE: 25 Year Old VS Drive System Integration Help
Let me know if you would like the contact information.
RE: 25 Year Old VS Drive System Integration Help
Again Thanks,
beauxdog
RE: 25 Year Old VS Drive System Integration Help
Most isolators will accept the negative side of the voltage output being a common (even ground) which would mimic the present system, it seems.
What am I not seeing, beauxdog?
RE: 25 Year Old VS Drive System Integration Help
RE: 25 Year Old VS Drive System Integration Help
"Venditori de oleum-vipera non vigere excordis populi"
RE: 25 Year Old VS Drive System Integration Help
http://www.elkor.net/etvi.htm
RE: 25 Year Old VS Drive System Integration Help
If you need an attenuated replica of the master signal - is this correct? - then why not create some additonal DCS points and use the DCS to provide the requisite scaling through software to drive additional 4-20mA outputs, one with 100% span and the others with reduced spans that your operator or engineer can adjust to suit the process?
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If we learn from our mistakes,
I'm getting a great education!
RE: 25 Year Old VS Drive System Integration Help
You typically have one motor called the lead motor. A pot will supply a board called a LMR (Linear master reference). This board will adjust the ramp reference for the system, speed of shutdown etc. The signal would then go to 4Ia cards. Real simple cards just op-amps really. They have pots for adjusting each drives speed. You could build your own. You'll also need something to automaticly adjust the speed of each motor slightly. For instance in a web application dancer rollers to keep everything running together. I could probaly get you drawings of a complete machine boards etc. I also have drawings of every Reliance drive ever built. I think! I have working on systems like this for about 30 years. You can do it many different ways PLC's etc, For your drives you may be on the right track for the simplest system. I'll see if I can get a web sight for you and post it.
RE: 25 Year Old VS Drive System Integration Help
RE: 25 Year Old VS Drive System Integration Help
Full disclosure: this is a product my company makes, analog-to-resistance transducer.
http://www.kele.com/olcat/ot8/RES-1.PDF
Special ranges happen all the time too.
Holler at me if you need any additional data.
DWeigel@kele.com
RE: 25 Year Old VS Drive System Integration Help
RE: 25 Year Old VS Drive System Integration Help
RE: 25 Year Old VS Drive System Integration Help
RES-1-S is "special range" version, you specify the minimum and maximum ohms output. It can be up to 1 megohm, minimum span 30 ohms. You can find it in the "output transducers" section of www.kele.com under Kele catalog.
Best to ya,
Old Dave
RE: 25 Year Old VS Drive System Integration Help
John,
Here is the pricing for most of the boards we build. They are the same as
the ESI boards except we added some features that weren't on ESI's. Balus is
our technician who builds these and he did all of them for ESI for 25 years
before coming here.
Pricing:
PPD-4-320 $605.00
4IA $430.00
LMR3 $410.00
ACC-FR $605.00
PS-1 $ 52.00
PLC1 $1150.00
PWR $358.00
Mt. Vernon has terms of 1% 10 days on the purchase orders to us. I will get
back with you on a meeting for next week as soon as I can get a date Balus
and I can both make it. Thanks Charlie Johnson 1-423-629-4014 FAX
1-423-629-4177
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1/28/05