Motorized Pot

[ptonsparky]

Customer would like to control a VFD output from two different locations. Preset speeds won't work for this application so I am thinking motorized potentiometer. Anyone do this before or have a simpler suggestion?

 

[LarryFine]

See if the manufacturer has provisions for remote control.

 

[gar]

101001-1908 EST

Need much more information on the application.

Distance from control points to VFD?
Volatile or non-volatile retention of the pot position?
Resolution of pot setting? For example 1024 positions.
Voltage across pot?
Load resistance on wiper?
Isolation voltage required between control point(s) and the VFD electronics?
Power available at VFD for circuitry? Like 5 V, +/-12 or 15.
Response time?
Will a D/A converter or equivalent work?
How are controlling points to operate? Pushbuttons or what?
Is power available at the controlling points?
How important is the remote capability? In other words how much money is available?
Are both control points to have equal priority of the control function?

.

 

[ptonsparky]

101001-1908 EST

Need much more information on the application.

Distance from control points to VFD?
Volatile or non-volatile retention of the pot position?
Resolution of pot setting? For example 1024 positions.
Voltage across pot?
Load resistance on wiper?
Isolation voltage required between control point(s) and the VFD electronics?
Power available at VFD for circuitry? Like 5 V, +/-12 or 15.
Response time?
Will a D/A converter or equivalent work?
How are controlling points to operate? Pushbuttons or what?
Is power available at the controlling points?
How important is the remote capability? In other words how much money is available?
Are both control points to have equal priority of the control function?

.

Excuse me but I may have to go back to school for a few years to answer all of these.

distance to furthest 30'
position should be relatively stable
Simple 5k single turn. (What they use now.)
10v
Don't know
12v from VFD
Not critical
?
Pushbutton
We have 24v dc supply readily available
They can afford it, but lets say budget is $1000
They will be equal.

My best guesses anyway.

The VFD in question feeds product to another. They must be started while the operator is in the immediate area. Once up and running the operation is monitored in a relatively clean and quite location. They would like to be able to adjust the VFD from both areas.

 

[petersonra]

Many VFDs have what is called a MOP function built in. One input is used to increase speed, the other to decrease it. Its not a physical pot but it works a lot like a motorized pot does where you use a PB to run a motorized pot CW and another PB to run it CCW.

All you would need is a couple PBs run from the two locations to VFD inputs. Dirt cheap.

 

[ptonsparky]

Many VFDs have what is called a MOP function built in. One input is used to increase speed, the other to decrease it. Its not a physical pot but it works a lot like a motorized pot does where you use a PB to run a motorized pot CW and another PB to run it CCW.

All you would need is a couple PBs run from the two locations to VFD inputs. Dirt cheap.

Perfect!! Just had to read a bit further down the list of parameters for digital inputs.

 

[GeorgeB]

Many VFDs have what is called a MOP function built in. One input is used to increase speed, the other to decrease it. Its not a physical pot but it works a lot like a motorized pot does where you use a PB to run a motorized pot CW and another PB to run it CCW.

All you would need is a couple PBs run from the two locations to VFD inputs. Dirt cheap.

Interesting ... technology marches on. 10 years ago, I used a then cheap PLC with analog output (about the $1000 point) to generate the +/-10V signal complete with the slow change for 1 second, faster for 2, then fastest change rate. This was the same technique used for timer adjustments.

 

[justdavemamm]

Interesting ... technology marches on. 10 years ago, I used a then cheap PLC with analog output ....

And I saw one in a new design earlier this year. An Eaton plc (ELC PA series) and this was its only function in a panel full of relays.