Teco vfd speed control pot ?

[seanb]

Teco 2 hp vfd I wired a remote on/off and a speed control

I have upper limit set to 120hz and lower set to 0

At about 70 hz speed control jumps to 0

Same thing happens when increasing speed.

It’s like the pot is extra sensitive for part of its range

Anyone experience this or have any ideas

Potentiometer is a cheap Chinese one from amazon

 

[cathead]

It's probably the potentiometer. I'm using a 10 turn pot and it has worked flawlessly at all speeds. Also,
the speed control is just silky with 10 turns. Likely the pot you are using has a dead spot in the middle of the carbon,
(that is if it is a carbon resistor).

A wire wound resistor would be my choice to use.

 

[gzoerner]

seanb,

Check to see if the potentiometer is linear. (Uniform resistance change per degree of rotation.) An audio taper pot could exhibit the behavior that you report.