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Potentiometer Wanted
RedAvon - 9/11/21 at 11:43 AM

Hi folks,

I really did think this would be a simple purchase, as I used to have loads of components lying around over the years. Must be the way consumer electronics has gone these days I guess.

Anyway, I'm looking for a 10k Ohm, 2 Watt, rotary, single turn, linear, panel mounted potentiometer for the VFD conversion on my lathe.

Everything seems to be low wattage (audio type), out of stock, from America, or with a long lead time and poor quality (China).

Does anyone have a suggestion to source one of these, or have one knocking about that I could buy and pay postage.

Thanks
Ian

gremlin1234 - 9/11/21 at 12:02 PM

https://cpc.farnell.com/te-connectivity/404802692038/potentiometer-10k/dp/RE06801?st=10k%20potentiometers

crimondbanger - 9/11/21 at 09:33 PM

if it controls a VFD any old wattage should do , its very likely just a 0-5v signal no current is going to be dissipated.

RedAvon - 10/11/21 at 07:44 AM

Thanks gremlin for that link.

Crimond - thanks. I had thought I could use a lower wattage originally but the manual specifies 2watt minimum?

It's a 24v control voltage on this Allen Bradley.

Ian

crimondbanger - 10/11/21 at 10:10 AM

Ahh

As its a decent brand it might actually need a 2w pot as it could use current feedback rather than voltage, its more accurate for control boxes that are a long way from the main box.

Best to try the usual suspects

https://www.digikey.co.uk/
https://uk.farnell.com/ (as above)
https://uk.rs-online.com/web/

Toys2 - 10/11/21 at 10:49 AM

quote:
Originally posted by RedAvon
Thanks gremlin for that link.

Crimond - thanks. I had thought I could use a lower wattage originally but the manual specifies 2watt minimum?

It's a 24v control voltage on this Allen Bradley.

Ian


What's the part number of the drive? I know them very well - I used to work on drive support at Rockwell for 10 years

Edit, I've had a quick look, I'm guessing you've got a Powerflex 525
The manul does mention 2W this has got to be a typo (older drives have a minimum 2K Ohm requirement - maybe this is where the typo came from?)
On the 525, the logic is 24V and the pot power supply is 10V, this works out as only 0.01W with a 10K Ohm pot

Fitting a lower wattage pot can't damage the drive, as it will still pull the same current

These use a voltage divider into a very high impeadance input, so really any pot should do
Just get a reasonable quality pot, cheaper ones can be a bit unpreditable

[Edited on 10/11/21 by Toys2]

RedAvon - 10/11/21 at 04:15 PM

Thanks for your replies and information.

The drive is Powerflex 4M. Series A 22F-A8PON103

Cheers

gremlin1234 - 11/11/21 at 08:11 PM

I have looked though the 'spec' of this, and it does indeed say a 2W pot should be used, however it also shows a 10V reference at 15mA max (10V x0.015A = 0.15W. )
I also suspect it should show 2Kohms min. (10V/2K= 5mA and then a good safety margin)
whatever, if you use the pot linked to earlier, it should certainly work.

http://bph.hsph.harvard.edu/datasheets/Allen-Bradley-22F-A8P0N103.pdf

[Edited on 11/11/21 by gremlin1234]

Toys2 - 12/11/21 at 12:46 PM

quote:
Originally posted by RedAvon
Thanks for your replies and information.

The drive is Powerflex 4M. Series A 22F-A8PON103

Cheers


Yep, my advice for the PF525 stands for the PF4, a good quality pot will be fine, no need for 2W

The PF4 is a good little drive, do follow the mounting and clearance advice (76mm top and bottom) in the the manual, as they don't like getting hot
Mount it vertically, heatsinks upright, not laying on it's back

I can't remember when they stopped including the full manual, just the quick start guide

Here's a link to the full manual
https://literature.rockwellautomation.com/idc/groups/literature/documents/um/22f-um001_-en-e.pdf

[Edited on 12/11/21 by Toys2]

RedAvon - 12/11/21 at 05:51 PM

Thanks gremlin, and for the link. I hadn't realised that the analogue circuit is 10v - which is separate from the 24v control circuit.

Thanks Toys2 as well for the advice. I'm thinking of mounting it vertically under the chip tray at the head stock end in the middle of the base end panel, so it will have a good thermal connection to the metal lathe base. I've rewired the original 3 phase controls on the front panel and will add the pot to this panel for speed control.

It does look like a well made unit, thanks for the manual link.

Cheers guys.

gremlin1234 - 12/11/21 at 09:07 PM

quote:
Originally posted by RedAvon
Thanks gremlin, and for the link. I hadn't realised that the analogue circuit is 10v - which is separate from the 24v control circuit.

Thanks Toys2 as well for the advice. I'm thinking of mounting it vertically under the chip tray at the head stock end in the middle of the base end panel, so it will have a good thermal connection to the metal lathe base. I've rewired the original 3 phase controls on the front panel and will add the pot to this panel for speed control.

It does look like a well made unit, thanks for the manual link.

Cheers guys.

I'm just reading the manuals, (but I do have an electronics, computing, and black box testing background) Toys2 is the expert