Pot and switch types for remote VFD

Ropata

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Hi Guys,

I want to wire in some on and off push buttons and speed control pot to this cheap 2hp VFD I am about to hook up to my new belt grinder. I just want the unit away from the dust and have a smaller better looking panel to control from. Can anyone please give me some advice about what rating and size etc for the pot and buttons?
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Most VFD control circuits are low-voltage low-current and any switch will work fine.

The potentiometer resistance value you get depends somewhat on the input resistance of the VFD control, which is usually in the specifications. A general rule is the pot resistance should be 1/10 of the input resistance of the circuit so it appears as a voltage source to the VFD input port. Typically the input resistance of the VFD is 10K ohms, so a 1K or so pot would be appropriate. Check the VFD specs and purchase accordingly.

The power rating of the potentiometer is an Ohm's law calculation: Power=Voltage squared divided by resistance. That calculates the actual power dissipated by the device, prudence dictates getting a pot rated at least twice the power dissipated as a safety factor.

Have fun!

Stu

Uh oh - seems I have double posted and cannot figure out a way to delete the doppelganger. Editing, no problem. Deletion? I can't find that button!
 
Thanks Stu. I can't seem to find anything in the badly translated manual. It seems quite a popular model. It's the same one that Banggood have been sending out to Youtubers to test. Here are some photos of the relevent pages I think. Does it look like I need to install jumpers if using a remote pot to you?

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it does look like you jumper 1 and 2 for external rheostat pot.

cannot quite read the value on page two. You could just try a 5K one.

Yep most any small switch will do.

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That looks like a Huanyang VFD. The manual that I have for mine shows a 10K ohm potentiometer. You will want a linear taper potentiometer rather that an audio (logarithmic) taper. (All of the Teco VFD's that I have seen also use 10K ohm pots)



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For momentary push buttons, you will have to add relays. Attached is the configuration for my remote. Probably a bit more than you want. I jdidn't have reverse because it was for an auxiliary high spindle that was never going to need reverse. What functions do you want in the remote?

Ken

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If it's like my Huanyang VFD it supports "3 wire control". I assume for a grinder you don't need reverse. Two momentary buttons should work, a RUN button that is NO (normally open) and a STOP button NC (normally closed). No relays are required for this VFD. The controls are low current/low voltage so electrically just about anything will work. You may want to look for something that is mechanically strong and sealed well for dust. If you don't need reverse the NO (normally open) button connected to D2 in the diagram below is not required.

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I assume for a grinder you don't need reverse. Two momentary buttons should work, a RUN button that is NO (normally open) and a STOP button NC (normally closed). No relays are required for this VFD. The controls are low current/low voltage so electrically just about anything will work. You may want to look for something that is mechanically strong and sealed well for dust. If you don't need reverse the NO (normally open) button connected to D2 in the diagram below is not required.
Most belts are directional, but I have seen some belt grinders built to be reversible. I guess you can always flip the belt around.
 
Hi Guys,

I want to wire in some on and off push buttons and speed control pot to this cheap 2hp VFD I am about to hook up to my new belt grinder. I just want the unit away from the dust and have a smaller better looking panel to control from. Can anyone please give me some advice about what rating and size etc for the pot and buttons?
View attachment 248979View attachment 248980
On my B&S surface grinder, I installed the same basic VFD as you are using, only 2.2KW (3 HP) and without the potentiometer. Only $10 more on eBay than the 2 HP version. I installed the VFD in a project box after cutting round holes in the top and bottom for a muffin fan (top) and filters (top and bottom). The fan has a sheet of thin polyethylene on the top to also help keep grit out. The poly bends upward when the fan is running, and settles back down when the fan stops.. I removed the front covers of the VFD completely, and then removed the display/control panel from the front cover. I mounted the display/control unit to the front of the enclosure and added an oak frame for looks. The wiring tape from the VFD to the display reaches easily. There are also remote controls for spindle speed and spindle on/off installed in the front cover of the project box. They are programmed to control the VFD. Since I got this finished, I have never touched the buttons on the VFD control/display, which are known for being less than robust, and will only use them if and when I need to reprogram something. The added switch and pot are cheap and easy to replace if needed, and AFAIK spare parts are not available for the cheap Chinese VFDs. The remote controls are also a lot nicer and more convenient to use. It works good.
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Hi Ropata,
you are going to need maintained contact or latching switches for the VFD you have chosen.
i installed the same type of VFD on my shenwai sw 900b, but mine is the 2.2Kw (3hp) version
a 10K potentiometer will work fine.
as far as switch rating is concerned, the voltage and amps are low when you use the DCM power
24volt/ 5 amp rating would be more than sufficient for the switches
 
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