Reversing Switch Wiring 3Phase Motor

I have a small VFD controlled 3 phase 1/4 HP motor running my lathe. I purchased a YMW26-25/4 switch from Banggood that I would like to use to provide the capability to reverse the motor. I would like to install it between the VFD and the motor. There was no wiring diagram included with the switch, but I found the switch configuration by googling the switch model number. I am still unsure as to how to connect it as I am not an electrician. I have attached the switch configuration. Any help would be greatly appreciated. I am assuming it can be done. Thanks
Rick

It is my understanding that it is recommended that NO switch be placed between VFD and Motor as serious damage can happen to the VFD unit. All the VFD's that I have looked at can reverse direction on the fly so why would you need a switch anyway?

I let my VFD do the reversing with a single pole, double throw switch sending the appropriate signal to the VFD. However, for the purpose of this discussion, if these motors are just like my brushless DC motors for r/c, you should only need to swap two of the three legs for reverse. This is probably what the VFD does internally.

bruedney said:

It is my understanding that it is recommended that NO switch be placed between VFD and Motor as serious damage can happen to the VFD unit. All the VFD's that I have looked at can reverse direction on the fly so why would you need a switch anyway?

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Accordingly, it looks like you could hook up contacts 1-2 for the forward low-voltage CONTROL input and 3-4 as the reverse CONTROL input on your VFD. My guess is that 1 and 3 would share the Common terminal, 2 would go to the forward input and 4 would go to the reverse input. Study the manual.

We switch the leads after the VFD a lot. It's the leads going to a VFD that can be critical. A CT current transformer monitors the power coming in for all three phases.
If you connect L1 to 1 and 3
L2 to 5 and 7
L3 to 9 and 11
And
T1 to 2 and 6
T2 to 4 and 8
T3 to 10 and 12
T3 will stay the same but T1 and T2 will switch.

Thanks for the responses. I guess I should have been clearer with my description. My VFD has 120 volt single phase input with 220 3 phase output, so I don't know how to put a reversing switch ahead of the VFD. It seems to me that Aerofourcycle's information will work. Rick

A vfd has a number of low voltage connections that can control all sorts of conditions
Look at the manual for that model. It is nice to have some low voltage switches
controlling the
Direction, speed, and braking, Accel and Deccl.
Unfortunately some manuals are poorly written, leading to owner fustration.

Lots of things in life can be done, however it doesn't mean you should do so.

The vast majority of VFDs sold are already configured to support reversing the motor electronically. This normally requires a toggle or selector switch tied to a predefined input. Sometime it is easier to use a supplied "remote panel" that the drives designers sell.

You want to use the supported reversing method because modern drives offer features that help protect the motor in their use. It is also commonly cheaper to use low cost switches. Further an operating panel can be built close to the headstock with the rest of the electronics sitting in a control panel.

rickhann said:

Thanks for the responses. I guess I should have been clearer with my description. My VFD has 120 volt single phase input with 220 3 phase output, so I don't know how to put a reversing switch ahead of the VFD. It seems to me that Aerofourcycle's information will work. Rick

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What mode are you using the VFD? Simply as a phase converter? Or are you using it for the variable frequency speed control, and maybe even a vector drive? I most certainly would not do anything with the input or output of the VFD, and allow the VFD to control direction, starting, and stopping. The only time I might consider what you are doing is if I was using it as a pure phase converter with a fixed 60hz output, and I had multiple 3 phase motors that needed to run off of it, and ONLY if the manual said it was ok.

Personally I would use the vfd to control direction .Its a few years since I retired and things move on rapidly but Iv not seen the set up you are planning on doing. The switch as drawn will work but switching this way can shorten the life of the VFD
If its a Mitsi vfd then STF and STR are the terminals you need for Omron I think its terminals 1 and 2 but check in the book for youre vfd
best wishes
frazer

I am a perfect example of having a bit of knowledge being a dangerous thing. At least now, I know what I don't know. My VFD is a FUJI AF-300 Mini with 120V, 1ph input with 230V 3ph output operating a 1/4 HP motor. I picked both the VFD and the motor up at a Cabin Fever Show several years back. I connected them and they worked! I was happy until now. Thanks to those of you who have educated me a bit on VFD's. I have the manual and will see what I can come up with. Hopefully no "magic smoke".
Rick

Line from vfd to motor should be direct and I would use 14 or 16awg wire.
before your vfd input you should use a fast acting fuse or circuit breaker like this:
EATON FAZ-C3/2-NA Miniature Circuit Breaker, 3A, C curve
You can set up vfd for variable speed: 10 to 80 hz, acceleration time , deceleration time,increased torque at low speeds,forward or reverse, braking and
many other functions(many not used by hobbyists).
A lot of possibilities.

You use the control inputs to the VFD, in conjunction with the correct parameter settings, not a switch in front of or behind the VFD.
Being unable to work this out or find details is a function of cheap VFDs with poorly written Chinglish manuals.

The VFD will reverse the rotation with out any help. Your switch will over load the VFD an shorten it life greatly. If you look at your poorly wrote manual there might be something about the wiring bar and what you have.

Rick
In respect to your VF controller, all of the above replies are basically correct. I have five of these controlers running everything from my lathe to CNC routers and surface grinder. In most cases, I have had to reconnect the motor from a star connection to a delta connection. The Asian controlers are generally 220 volt three phase output so their no use with 440 volt star connected motors. If you are in the U.S., your star connected motor is likely to be 220 volt and therefore OK.

In respect to reversing a three phase motor, you simply need to swap any two phases. When you use the motor in conjunction with a VF controller you can't insert a switch between the motor and the controller as there is a high likelihood of blowing a pair of the output Mosfets. All of the controlers have the facility to reverse direction electronically either on the control panel or externally.

If you need to have the reversing switch externally, you will need to change the appropriate register eg the value from 0 to 1. Quite easily done.

Another trap for first time users is to appreciate that these controllers are usually set up for 400 Hz where you need 60 Hz (I assume). You need to set the maximum frequency to say 70 Hz and the lower frequency to say 35 Hz. If you don't, you will get no power out of your motor because it will be running at less than half voltage. On my lathe, I have brought out to an external box the start, stop and frequency control so that I can vary the speed via a control knob.

Finally, I have a complete set of manuals which I am happy to provide to you via a private email. They make it easy to program the unit plus provide wiring diagrams for external control.

Bruce

Thanks to all who have provided information. I had put this task on hold, but with all of the help I have received, I will give it a second look. I have the manual for the VFD and it seems to be well written. If anything it has more information than I think I need.
Rick

Hi Rick,
it‘s very simpel. On the terminalblock in the VFD you will find an installed jumper between „FWD“ and „CM“. Remove this jumper and install a change switch. The common wire from the switch goes to „CM“, the n/c to „FWD“ and n/o to „REV“. Now you can switch the lever and the motor will turn backwards. You can do this while the motor is still running, the VFD will reduce the revolutions to zero and then starts the motor in the reverse direction.
Sorry for my bad English, but I‘m German.
Werner

rickhann said:

Thanks to all who have provided information. I had put this task on hold, but with all of the help I have received, I will give it a second look. I have the manual for the VFD and it seems to be well written. If anything it has more information than I think I need.
Rick

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On my hitachi wj200 there are 200+ different programming options.
I use about 25.