I'm in the middle of converting my Denford Orac CNC lathe to run from Mach3, and have come to a bit of a grinding halt! I'm planning to use the original VFD to control the motor, using a Digispeed or similar to interface it with Mach.
However, I can't find the pin-out connection details for the particular VFD which was in my 1983 Orac - a Parametrics Parajust (Barry Wright) FHP VFD. It has three terminal blocks for connections - TB1, 2 and 3. TB's 2 and 3 are easy - they're for the 1ph input and the 3ph out to the motor. However, TB1, which has 6 pins numbered 1 to 6, is puzzling me.... Does anyone know what goes where (I'm guessing there will be pins for things like drive enable, forward/reverse, and a 0-10V signal (or similar) for speed.
Any info would be much appreciated.
I would contact the makers but they were taken over by ABB and none of the Parametrics VFD's seem to be around anymore.
I Have a 5hp. parajust it just went bad. I have spoken to a few techs from parametrics and they say get a new vfd drive they also sell them.
Do you have any contact details for Parametrics? I've tried to find their details but was under the impression they'd been bought by ABB??
Here some info I recived about 2 weeks ago there some info here on VFD if your looking for new also some info on RPC
Thank you for your telephone call today. Here is the information you
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I will get you a link or phone # later today.
Excellent - many thanks mmachining
I'm sorry it took me so long to check on this. I saw your post on a Yahoo group over the weekend and have been busy this week.
The FHP TB1 Terminals are:
1 - Speed Pot CCW
2 - Speed Pot Wiper
3 - Speed Pot CW
4 - Start Pushbutton
5 - Start and Stop Pushbutton
6 - Stop Pushbutton
You can also use an ON/OFF toggle switch or relay between TB1-4 and TB1-6 instead of the start stop pushbuttons. The Pot is a 5K 2 watt. The start pushbutton is normally open and the stop pushbutton is normally closed. Both are momentary. The manual also says shielded cable shoud be used for all TB1 connections with the bare (drain) wire tied to TB1-4. Don't let the other end of the shield touch anything, tape or heat shrink that end after clipping the shield (drain) wire.
Hope this helps. Be careful with it. I seem to remember these drives liked to pop a lot. They are fairly crude but should be quiet as a mouse since they aren't PWM drives.
I have more info if you need it.
Last edited by Mike Nash; 09-07-2006 at 01:50 PM.
Reason: Formatting went south on posting
www.buycontrols.com, scan down on left of screen to parajust and you will find it.
Many thanks for the info! It tallies up nicely with what I had started to guess based on some very incomplete electrical drawings I had for the original machine, but I'm not very confident in my electrical knowledge so it's great to have things confirmed!!!
I have a couple of questions related to the speed pot connections (please bear with me if these sound stupid, but I'm a Mech Eng by trade and things electrical tend to scare me, so I want to be sure I've got it right before I wire stuff up!!!):
Terminals 1, 2 and 3 are Speed Pot CCW, Wiper and CW respectively. So how would the pot get connected - obviously the wiper goes to pin 2, but I thought the other pins on a pot are usually 0V and +V reference (I'm guessing +10V in this case as it seems standard on most inverters to use 0-10V control signals), so which goes where?
When this motor and inverter gets refitted to the lathe, I'm planning to use a Digispeed board, which takes in a PWM signal from the control computer and converts it to a 0-10V signal to go to the inverter (the Digispeed is fully opto-isolated so I don't need to worry about elevated grounds from the inverter killing the PC). So I'm trying to get straight in my head to which 3 pins I'd need to connect the ground, +10V reference and wiper (0-10V) connections of the digispeed. I'm not worried about running the lathe in reverse, so would only need either CCW or CW to be connected.
Again, many thanks for your help, and apologies for all the questions
Finally - it sounds like you've got a manual for the drive there? If I was to pay copying and postage, would there be any chance of getting a copy?
Last edited by clarkea1; 09-07-2006 at 03:20 PM.
Reason: I can't spell!!!!!
I see where the Digispeed is really designed for the KB drives so your translation will be:
KB to Parametrics
P1 becomes TB1-4 (0 Volts)
P2 becomes TB1-2 (0-10 volts input)
P3 becomes TB1-3 (+12.4 volts output)
I used TB1-4 instead of TB1-1 because there is a 100 ohm resistor between TB1-1 and common which is TB1-4. Also the manual says to use TB1-4 with external reference voltage. The only other issue here is that the Parametrics puts out 12.4 volts through an 820 ohm resistor to TB1-3. I would suggest putting a 4.7K (4K7 for you UK folks) 1/2 watt resistor between TB1-3 and TB1-4 to provide proper loading to get the supply back to about 10.5 volts. The problem with this is that switching to manual with a 5K pot is going to limit max speed in manual mode to about 88%. I don't really see any other problem as the wattage on the 820 ohm will be far less than it is rated for.
One further note. The start/stop logic is 6 volt DC, but the circuit common is tied to the positive DC bus and there is no isolation between the SCR bridge and the mains input. So be careful.
Let me see a little later what I can do about the manual. Our copy is a photocopy and there are 20+ 8.5x11" sheets, single sided. Perhaps I can take pictures and put them up on the web. Scanners are too slow.
Many thanks for clarifying this and taking the time to explain things!!! I suspected most of the logic inputs would not be isolated etc, so I will take care when I wire the drive up.
I'm away with work until next Friday, but will try the drive out when I return. Hopefully there will be no sparks.
It would be much appreciated if you could put the manual on the web.
Did anyone ever find a number for the parametrics technician? I also have a 2hp parametrics i just inherted.