Electrical pot switch help

[j king]

I bought a new Baldor drive and I need a potentiometer for speed control.It says 1kohm minimum.
I went to radio shack and they didn't have a 1 k. 5 was smallest that they had.Since it says minimum what will work? Do a need a 1kohm switch? Thanks.
If anyone is curious it is a Baldor VS1mx23-2T.
I am hoping this one works the same as the others I have.it is physically larger than 3 of the other drives I have so hopefully it's a good one.��
Thanks. Jim

[MaxHeadRoom]

Your OK with anything between 5k and 10k, it has to be a linear pot. Not logarithmic.
You should use 1k minimum as the manual states, if 0.5k, may load the analogue supply.
Max.

[J Tiers]

Anytrhing under 1K may not allow the full range of input voltages. above 10K, you may get non-linearities, where the low end of speed is pushed toward one end of the rotation.

That's a good drive, it is actually made by Invertek in the UK. There may be some differences from the standard Invertek as far as programming, etc, because it likely has custom software. I know a fair bit about those in their Invertek form, and have manuals, and some service data from back when I was associated with the US distribution folks.

[j king]

Ok guys thanks.
Good to hear J Tiers..
I ordered a couple off amazon. They are 1k ohm. These will work ok then.I am a prime member and could get them in 2 days for cheap so went ahead and ordered them.
Here's what I ordered...

[j king]

Hey J Teirs.. I'm gonna run this off 220 single phase as I do all my Ac drives. Is it correct to run the 220 legs to l1 and l3 ..that's how I have been doing it and it's worked. Ignorant is bliss..lol

[j king]

Maybe I get a you suck on this I hope. Paid 100 and its new.well is suppose to be..will see. It looks new

[J Tiers]

If it is set up for single phase in, and most of the Invertek types are, them it should be labeled L1 and L2/N. That may not be the case with the Baldor version. I'll see if I can get a Baldor Manual

Found one

http://www.electricmotorwholesale.com/BALDOR-VS1MX23-2T.html

According to that, the MX23 number codes to a 230V 3 phase input 3HP unit with IP55 enclosure and internal brake transistor. Maybe not what you had in mind. An MX83 would be 230V 1phase, 3 HP.

It is unknown to me whether the 3 phase version will be happy with single phase, they DO vary the amount of capacitance between 1 and 3 phase units, I don't know if they change the diodes. The newer units are made differently than the older ones.

The specs imply that model is OK with single phase.

I've run a lot of them that way, and while rarely at max power, they caused no trouble. Those were Invertek labeled units, which might be different.

[j king]

Thanks J. Much appreciated.I have muddled my way thru these drives for many years.. Always succeeded.I have a large 10 hp lathe with an ac drive that I run on single phase. If it trips from too heavy of a cut I turn on the rotary converter and have full power. Works great like that. Lol
If I recall correctly I wired l1 and l2 and used l3 as the generated leg and it works that way.

[Paul Alciatore]

Those don't look like very high quality to me. You may be better off with the Radio Shack for longer term service.

As for the value, 1K or 5K, you are probably better off with the 5K. The 1K was specified as the minimum acceptable value. Lower values will draw more current and possibly load down the Voltage source. The 5K will draw less current.

If you want a better quality pot, you can go to an electronic supplier like Digi-Key or Mouser.

Ok guys thanks.
Good to hear J Tiers..
I ordered a couple off amazon. They are 1k ohm. These will work ok then.I am a prime member and could get them in 2 days for cheap so went ahead and ordered them.
Here's what I ordered...

[macona]

Yeah, those pots are kind of crap. I always try to use the AB series J pots, they hold up to poor conditions, they are what you would find in tig welder pedals and on most industrial controls.

http://www.ebay.com/itm/ALLEN-BRADLEY-10K-OHM-TYPE-J-2-WATT-POTENTIOMETER-1-PCS-3-8-SHAFT-REFURB-/331927145143?hash=item4d48664ab7:g:P6gAAOSwMmBVz23S

http://www.ebay.com/itm/Allen-Bradley-Type-J-1K-Pot-Potentiometer-NNB-JAIN056S102MA-/321994258839?hash=item4af85a7997:g:GH4AAOSwa-dWrXcW

[MaxHeadRoom]

Those don't look like very high quality to me. You may be better off with the Radio Shack for longer term service.

As for the value, 1K or 5K, you are probably better off with the 5K. The 1K was specified as the minimum acceptable value. .

+1 on the 5K, that is general industry standard value.
Max.

[J Tiers]

That drive does accept 1K, but that is the lowest, because the regulated power supply for the speed control can't drive more load (less resistance) than that.

Question is whether the pot shown really IS 1K. That's the nominal, but those shown above typically have a 20% tolerance, so they can be as low as 800 ohms (or higher up to ~~1200 ohms). Agree that 5K is a better choice for that style.

Those controls are not really "crap", they are a decent consumer product control. But not really industrial. All that really means is the life is shorter in total turns, and there may be a little more noise as you turn it. The noise is no issue, the inputs are filtered, and the life is likely to be long enough not to be an issue for home shop use. You can replace that one many times for the cost of the industrial AB or other manufacturer's industrial version.

Also, the shaft may be different from what you have a knob for, being a 6mm knurled shaft.

There is no concern about insulation, those VFDs have a totally isolated control circuit (as do virtually all units, these days).

[PStechPaul]

It is possible (on some VFDs) to drive the speed control with voltage that can be positive for forward and negative for reverse. I rigged up a simple circuit with a joystick that allows F/R operation:

I don't have a good schematic for this. The joystick has two 100k variable resistors, so it was necessary to convert the resistance to a voltage proportional to position. I did this with a constant current circuit. Then I had to convert the 0-5V signal to -10 > 0 > +10 for the VFD control input. I used a DC-DC converter to get the negative voltage from the VFD's +10V. I can sketch up a circuit if anyone is interested.

[J Tiers]

You CAN set up the Invertek drives that way, there is a parameter group for that, although you may need to get into the extended parameters to access it.

Whether that is preserved in the firmware for the Baldor OEM version, I do not know, have not looked up the parameters to see what is provided.

[PStechPaul]

Here is one possible circuit: