TECO N3 external potentiometer... Ohms?

Okay. I've read every piece of literature on this drive I can find. The only specification for an external potentiometer is: 0-10V/ 0-20mA/; 10-0V/ 20-0mA. I searched through the archives to find the proper resistance to get on this. This thread was the most relevant: http://www.practicalmachinist.com/v...ers-vfd/teco-ev-vfd-speed-control-pot-226345/

So, the question is: Do I need a 10kΩ potentiometer? If so, how do you know that from the given literature? FWIW: the literature. As mentioned in the previous PM thread, it would seem to be 500 Ohm, not ten-thousand if you just used Ohm's Law...

I just bought a 5K ohm pot from radio shack less than an hour ago

It's now fitted to a Siemens 420 MicroMaster VFD, and works perfectly. It's running now, can you hear it in the back ground?

the literature with this unit indicates <5K but 5K seems to be the ticket. Perhaps a similar value will work for the unit you have.

Only 3 bucks to find out, and SH has an assortment. 5k, 10k 25k etc.

Pots are cheap.

The trick is to get one with the right taper, so that the range of adjustment is well balanced. You don't want all the action in the top half or bottom half of the knob. And you want the finest control where is makes the most sense.

An audio taper might give you better control over low speeds for example.

Plus you can bias a trim-pot to put the sweet-spot where you want it, and/or make the bias adjustment switchable.

Luckily pots are cheap ... experiment.

link --> The Secret Life of Pots

Sounds like a royal PIA. There is literally one on the keypad... couldn't they have spec'd what it is? I think I'll stick with my straightforward UP/DOWN speed commands. Thanks for the info, guys.

Hi Arthur:

I got the following from the Teco N3 manual I found here.

The pot value is not critical as it is simply a voltage divider with its output applied to the AIN input.
The pot can be any value with the following constraints:
1/ It must not draw more than the specified Max current of 10mA from the +10V terminal as specified on Page 15. So using Ohm's law, the pot must have a value equal or greater than 1K Ohm.

2/ If you make the value too high it may result in noise issues.


10K seems to be a typical value although this manual shows a 2K pot on Page 8.

I would recommend a linear pot, any taper will make the speed change more at one end or the other but your choice.
I would also recommend a 3 turn pot which will give you more mechanical adjustment but that's just my preference.

MotorradMike--I owe you one There it was hiding in the p.8 diagram, and I was blind to it. Thank you; I appreciate the clear explanation!