Potentiometer Help

[chrisdicko]

Good Morning,
I have recently fitted a 10kΩ POT to and inverter to control the frequency.

I have added a dial to it for visual reference, ranging from 1 - 12, but when controlling the inverter, the POT doesn't do anything from 1-8 on the dial, but then from 8-12 it changes the frequency from 40Hz to 60Hz (I've set this Hz range on the inverter).

Will changing to a 1kΩ POT allow me to use the full range of the dial?

Both POTs are 1 turn (300 degrees)


Thanks a lot

 

[D.M.]

perhaps you should show a picture of what you're talking about so people can understand a little more.

 

[chrisdicko]

Hi,
This is the 10K POT
| Passives | Resistors, Potentiometers or Control Knobs | Resistors - Potentiometers | Wirewound

and this is the dial
| Passives | Resistors, Potentiometers or Control Knobs | Control Knobs | Shaft Fitting & Skirts

The dial is there, as you cannot see the inverter due to it being in a cabinet.

Just the 10k POT doesnt do anything for the 1st say 200 degrees of turning it, things only happen in the last 1/3 of the turn.

Would a 1k POT allow adjustment the whole (or nearly whole) of the turn of the POT?


Thanks

 

[MikeMl]

The pot you are using is "linear", meaning that the non-linear behavior of your oscillator is the fault of the circuit; not the pot. Post a circuit and we might be able to suggest something.

 

[chrisdicko]

Hi,
I'm sure it is the POT. As it does work, just not all the way through the 'turn'.

Fully anticlockwise, the inverter will show 40Hz, then you turn it and it stays at 40Hz until about 2/3 turning clockwise, then the frequency starts increasing, then when it is fully turned clockwise, the inverter will show 60Hz.

The frequency is correct, but I'd like the frequency to start to increase when you start turning the POT from anticlockwise before you get 2/3 through the turn. It's a 1 turn POT.

Here is the circuit diagram (basic)
**broken link removed**

 

[Roff]

Post the document that shows you how to connect and use the potentiometer.

 

[chrisdicko]

There isn't any documents, it just comes in a clear plastic bag.

 

[Roff]

There isn't any documents, it just comes in a clear plastic bag.

Then where did you get the idea to connect a 10k pot to the inverter?

 

[chrisdicko]

Just that was available there and then, and does work to a degree. Which is why I thought a 1k pot would be better?

 

[Roff]

You picked the **broken link removed**. Did you connect it correctly? See Fig. 3.5 on p.3-15 in the **broken link removed**. Look at the Frequency setting device.

Google is your friend.

 

[chrisdicko]

Hi,

I did use that manual to wire it all up, and that is how I have connected it.

It does work as I say, but no satisfactory.

It's like turning on a tap for ages with no water coming out, then on the last few turns the water begins to come out.......
That happens with the POT. You turn it 2/3 of the way, then in the last 1/3 thats when the frequency changes from 40 to 60HZ. I'd like it changing the frequency all the way of the turn.
Like turn a tap on, and get a dribble of water, then fully turn it on and get the full flow. dribble = 40Hz and full flow = 60Hz.



Thanks

 

[tcmtech]

Your frequency range needs to be reprogrammed on the VFD unit. Its likely programed for a 40 - 60 Hz band but the pot input is set for a 0 - 60 Hz range.

 

[chrisdicko]

Oh right, I see.

Yeah I have set the 40-60Hz band, but haven't looked to see if there is a setting of the POT input. Didn't think of that!


What would putting a 1k POT on do to it? Obviously that isn't the solution now as I first though, but just for my knowledge really....as I'm still learning as you can tell

 

[Roff]

I said:

Post the document that shows you how to connect and use the potentiometer.

You said:

There isn't any documents, it just comes in a clear plastic bag.

I said:

See Fig. 3.5 on p.3-15 in the **broken link removed**.

You said:

I did use that manual to wire it all up, and that is how I have connected it.

Do we have a communication problem?

 

[chrisdicko]

No documents for the Pot

Documents for the inverter.

Other inverters I've used, you haven't had to adjust anything for the input range, so didn't know/have the knowledge to look for that. I have read the inverter manual, but will have to go through it again, as I have obviously missed something relating to that.

 

[tcmtech]

On my VFD units the pot just creates a variable voltage referenced between the two lines that are 0 and 10 volts.
The actual value of the pots can be anything from 1K to 20K on most VFD systems.

Typically the rest of the upper and lower speed limits are all program based inside the VFD itself.

 

[chrisdicko]

Hi,
Yeah to be honest other Teco Minicon drives I've used, you just stick the POT on and that's it, no programming of the unit needed. Which is what I did this time with the CV series, but it isn't working as well, and the majority of the pot does nothing.

Which is why I thought I lower rate pot would do the job.....obviously not though, hehe.


Thanks