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Teco vfd speed control pot ?

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seanb

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#1
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

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#2
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

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#3
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.
 
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