Member postings for Peter Graversen

Thank you Norfolk,
Yeah - i'm feeling more and more sure, that the 12/10v thing is a non-issue. I actually JUST got an answer to an email i sent to Omron 4 days ago, 1 minute ago, and they were pretty laissez faire about it, just saying: Don't worry about the 12v, and just use a 2K resistor.". Thanks i guess .

The mechanical side, like hooking up SPDT switches etc. i'm comfortable with, so now the potentiometer crisis is over, i'm good to go .

Howard,
I wouldn't presume to understand your explanation fully, but from what you are describing, the pot does indeed function as a divider.
On leg connected to 0v common terminal, the middle wiper "leg" to the frequency reference input terminal, and one to the 12v frequency reference power supply.

John, the 2K (2w) pot i have ordered had no mention of whether it was linear or not. I assume it is.
Your idea about using the VFD with a reverse switch is great. I had actually already ordered the parts for i, and even a foot switch, so i can activate reverse without using my hand.
That part of the wiring actually seems fairly simple .

Thank you for the concise answer Clive - i really appreciate it.

Your answer makes total sense. I just wanted to hook up a VFD to my drill press, and though "hey - there's one from a reputable company - i will buy that" .

Opening the manual was therefore quite a shock, where one is supposed to know term like impedance . I asked a electrician friend of mine, but he is old school, and couldn't answer me.

So all i wanted to know was, if i would fry something, if i just hooked up a 2K pot to the assigned terminals and changed the appropriate parameters, or if there is something everyone that own a VFD knows, that i didn't.

Thank you again .

Ps. People in here are really kind and helpful. What a cool forum.

Hello Dave, and thank you for your kind reply. I was writing my previous post, while you were posting, so that's why my answer might have seemed odd.

You are indeed right that i misreported the impedance - it is indeed 20k-ohm. I don't even know precisely what impedance is in this context, and what effect it has.



I am ashamed to admit i don't even understand the calculator you linked to. I came to 500 ohm by thinking i would connect the resistor on the leg of the pot, that receives the 12v signal.

So my maths was as follows. I want 10v with a 2K pot, so I=E/R.
10v/2000ohm=0,005amp

I want to lose 2v, so R=E/I
2v/0,005amp=500ohm

But i'm sure your calculation is correct. I will see if i can get my hands on a 390 ohm resistor.

Thank you for looking that up David, and taking the time to respond i believe you are referring to this diagram:

I may not have been clear enough in my worry. As a beginner i see something that says it needs 0 to 10v, in this case the FR terminal, i start to question myself, before using a12v supply. Even with a potentiometer, i am regulation the voltage between 0 and 12v, not 0 and 10v.
I don't know if this over volting has adverse effects, or if the only side effect is, that the last sixth of a turn on the 2K pot, will be a "dead zone".

I might be overthinking this, but it seems very odd, that three terminals that are meant to interact has different voltages. On every other VFD i have seen, the frequency reference power supply voltage has been 10v, not 12v, so i thought i might have gotten my hands on some fancy VFD, where it's common knowledge that you are supposed to put a resistor in series on the 12v side before the pot, to get the 10v, since these terminals also can receive a signal from a PTC.

Here is the complete diagram of the VFD:

Hello.

I bought a second hand Omron Varidrive V7 frequency drive, and wanted to hook up an external potentiometer.

The online manual is very technical, and not written in a very accessible language, but i have found out that i have to connect the pot to three terminals. FP (frequency reference power supply- 12v 20ma), FR (frequency reference input 0-10v 20ohm impedance) and FC (0v common).

Since i'm out of my element, i'm bit confused that the FP terminal supplies 12v, but the FR terminal uses 0 to 10v as reference voltage to regulate the frequency.

They call for a 2K-ohm pot at 1/4w minimum as the analog regulator, so should i put a 500 ohm resistor in series with the pot, at the 12v side, to limit the voltage to 10v? (i don't even know if my maths is right, or really what i'm talking about )
The diagrams don't show this - only the 2K pot, but the descriptions are very vague, so supposedly this is something i should know in advance, but i don't .

On many of their other drives the reference power supply is 10v, but not on the V7 series.

I'm not good at this, and all i want to do is have a knob that can regulate the speed of my machine, without having to get a degree in electrical engineering .