VFD for a 3hp 2 speed 3phase motor on a mill...will it work ??

[DMS]

I have a Hitachi WJ200. One of the features (which I don't use, but it seems it would be useful here) is support for storing 2 sets of motor parameters. So if you have a similar VFD, you could tune it for the motor in "high" then switch the windings, and tune it for "low".

 

[metalmole]

Ok, got me a Teco drive, got my input protected with T type fuses, ....question, can I hook up the drum switch pigtail to the VFD and use the drum switch for direction control ??

 

[furpo]

Yes you can wire the drum switch to the inputs of the VFD for stop, start and forward, reverse.
Disconect the 3 Pase wiring from the drum switch and connect the low voltage to the inputs.

 

[bloomingtonmike]

Bringing this back up as I too just got a 2 speed 3ph motor for my mill and will be using a VFD on it.

Here is what I am thinking........

My motor has 6 leads.
For low speed VFD lines go to leads 1,2,3 and leads 4, 5, 6 are disconnected.
For high speed leads 1,2,3 are connected to each other and VFD lines go to leads 4,5,6

Was thinking you could do this with three 3PDT swithches - two for the 6 leads and one for the motor leads from the VFD.
Then was thinking why not have three 3PDT 24V coil relays controlled by the VFD outputs.

Relay #1 is the VFD motor-out leads
Relay #2 is Baldor motor leads 1-3
Relay #3 is Baldor motor leads 4-6

Wiring:

NC 3poles of Relay #1 go to NC of relay#2 and NC of Relay #3 is left empty.
NO 3 poles of Relay #1 go to NO of Relay #3 and NO of Relay #2 are joined together

Then you set up motor setup #1 to not do anything and it will keep all relays open/un-latched and the motor will be setup for the slow speed range

Then you setup motor setup #2 (maybe enabled by a switch?) to latch the coils and the relays will setup the motor output for the fast speed.

Just typing out loud. What do you think?

 

[rdhem2]

Mr. bloomingtonmike;

In short if I understand it correctly it is very possible. But unless very well documented, the next guy will not have clue of what is going on. Having done maintenance on things like this I hated it because it is so out of the ordinary. One wire breaks and you have no clue where it came from because you don't even know the purpose of such wiring. It also leaves a lot of room for OOPS by the operator if you use switches. When you design make sure you do your best to require no thought by the operator.

And I am so against operating anything over design speed which is usually 60 Hz. The items are not designed to stand the stresses involved.

 

[bloomingtonmike]

The WJ200 VFD makes full torque at .5hz so I see no reason to run the slow speed circuit of the motor. I will just wire the motor for the 1725rpm (digital tach is saying 1799) at 60hz.