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Really basic VFD wiring question

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Glenn Brooks

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#1
Iam getting ready to install and wire up a TECO VFD to my 3 Phase Baldor pedestal grinder. I have not wired up or worked with a VFD previous to this.

The VFD is a 110v input -220 3 Phase output unit. My 110 v shop circuit has the standard URL approved 20 amp, line (black), neutral (white), ground (green) three wire circuit configuration coming out of my sub panel.

So my question is: is it correct that I should connect my 110 v input neutral (white) wire to the L3(N) terminal shown in the attached photo of the VFD?

IMG_4394.JPG


AND, it should not be connected to the L2 terminal??

Note: the otherwise easy to understand tech manual that comes with the VFD has a diagram that says exactly the same thing as the picture - no instructions on how to wire 3 strand wire to the input side of the VFD.

Basically I've always been confused about which terminals (L1,L2,L3) are normally associated with 110v and 220v 20 amp circuits. - (well, I get the black wire should always be L1 - but have never understood what to do with L2 when wiring two wire circuits with two strand black and white (red) power cords)

Thanks for any clarification anyone can offer.

Glenn
 

Z2V

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#2
You would use L1, L2 , L3 if you were using three phase input, for single phase input you use L1(L) and L3(N).
The drive can use 115v or 230v input. For 115v you have a neutral L3, for 230 v you would still use L1and L3 , it will not matter which terminal black and red are attached to. For 230v you will not have neutral just two hots wires plus ground.
Hope this makes sense.
 
Last edited:

Z2V

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#4
Glenn
Look again, I was editing while you replied.
 

Glenn Brooks

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#5
Jeff, got it. thanks! Actually I also plan on doing another machine with 220 1phase to 3 phase, so your comments help explain both circuit methods. Particularily wiring in two 220 v leads to L1 and L3.

Glenn
 

mksj

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#6
FYI, this L510 120V model can only be used with 120VAC single phase input. The L2 terminal screw is missing on this model. As mentioned L1 is usually one phase of (split phase) 240 VAC and L2 is the second phase. It is usually important to balance the loads between L1 and L2 at the main panel. Also when wiring 120 VAC sockets off of 240VAC (with a neutral), I will wire one receptical to one side L1 and the other socket to L2, both share a common neutral and ground. This way you have a total of 15A x 2. I try to stay consistent as to wiring coloring (usually L1 is black, L2 is red), but it is a bit misleading on VFDs as the terminal labeled N(L3). Normally you do not want to get the neutral confused with a hot side power connection terminals, but the VFD doesn't care in this case. Also it can be confusing as to which terminals (L1, L2, L3) are used if a machine/VFD can run off of both single or three phase. Connection for single phase I would like to say convention is usually L1 and L3, but on my Taiwanese mill it is L1 and L2 (and is often the case for other machines I have worked on). My mill had no wiring manual or directions, so I had to follow the power leads to the transformer.

Incoming ground needs to be connected to the ground tab on the VFD and there must also be a ground connection between the motor and this same tab.

VFD 120VAC.jpg
 

Glenn Brooks

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#7
Ok, got the VFD wired into the grinder and everything is running well.

One more question.

My only issue is the "on" switch on the VFD is a tiny little thing. In fact, so small it's almost a safety hazard as it takes concentration and spot on contact to kill power. Bad features in an emergency.

So is it feasible to wire an industrial grade stop/start quick shut off switch to the grinder? If so, where would I wire it in the circuit. I assume between the VFD and power source, but read where shutting off and starting the VFD cause large power draws that kill switches.

Appreciate any info on whether this is feasible.

Thanks
Glenn
 

Bob Korves

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#8
Ok, got the VFD wired into the grinder and everything is running well.

One more question.

My only issue is the "on" switch on the VFD is a tiny little thing. In fact, so small it's almost a safety hazard as it takes concentration and spot on contact to kill power. Bad features in an emergency.

So is it feasible to wire an industrial grade stop/start quick shut off switch to the grinder? If so, where would I wire it in the circuit. I assume between the VFD and power source, but read where shutting off and starting the VFD cause large power draws that kill switches.

Appreciate any info on whether this is feasible.

Thanks
Glenn
Glenn,
You should be able to wire in an ordinary toggle switch to your VFD to turn the spindle on and off. That is a pretty basic function. Check your manual. On my surface grinder, I ran the spindle on/off switch and the potentiometer for spindle speed from the VFD to a convenient position. Also know that if the push buttons on your VFD ever fail, you will probably not be able to replace them, and the VFD will become mostly a throw away. Simple toggle switches and potentiometers are readily available and dirt cheap. You can also put them in a convenient location. I do not touch the buttons on my VFD at all after I got it set up the way I wanted it.
 

Eddyde

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#10
Glenn,

I have 4 of those Teco L510 drives currently working in my shop. The earlier version of the instruction manual was not clear, confusing. Here are the current ones. The Quickstart has most of the info you need.
 

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Glenn Brooks

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#11
Thanks Eddyde and Karl,

The newer manual helped. My manual is terrible. Worthless actually.

I wired up my two button switch three different ways and couldn’t get it to work. I think maybe the switch is a 3phase high voltage switch, so I’m headed out to look for a new paddle switch and see what happens.

Glenn
 
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