Thread: VFD for 1.1kW Coldsaw

Originally Posted by benhoskin

That is the main switch not the motor terminals. You need to see where the wires from that switch go too. It should then have other terminals you can connect to.
You do not want to connect the vfd output to that switch.

bwah, the VFD must not have a switch between it and the motor connections as the VFD must do the switching otherwise you will damage both the VFD and the motor.
While the motor is running the VFD MUST not be disconnected from the motor.

My guess is it will be something like in the following picture BUT lets get confirmation from at least one other source

forget about your blue L3, L2 and L1 labelled terminals they will no longer be able to be used because they connect to a switch underneath through to my green labelled L3, L2 and L1 labelled terminals.

The VFD has to be connected to my green L3, L2 and L1 labelled terminals.
Currently you will find metal strips between my green L3, L2 and L1 labelled terminals.
These have to be removed and placed in the orientation I have shown by the green loops in the picture.



Let me stress again that we need more confirmation before you connect up anything.

I think you're barking up the wrong tree Bob. Don't you need 6 wires to be able to change from star to delta?
I've no idea what the links are for.......... maybe for a motor that has the star point bought out to the switch terminals?

Stuart

Originally Posted by benhoskin

That is the main switch not the motor terminals. You need to see where the wires from that switch go too. It should then have other terminals you can connect to.
You do not want to connect the vfd output to that switch.

benhoskin, the red wires from the switch go into the motor housing.
there is no other terminal accessed externally on the motor.
access to red wires would require access into motor housing.

IMG_2178.jpgIMG_2177.jpg

Originally Posted by BobL

bwah, the VFD must not have a switch between it and the motor connections as the VFD must do the switching otherwise you will damage both the VFD and the motor.
While the motor is running the VFD MUST not be disconnected from the motor.

My guess is it will be something like in the following picture BUT lets get confirmation from at least one other source

forget about your blue L3, L2 and L1 labelled terminals they will no longer be able to be used because they connect to a switch underneath through to my green labelled L3, L2 and L1 labelled terminals.

The VFD has to be connected to my green L3, L2 and L1 labelled terminals.
Currently you will find metal strips between my green L3, L2 and L1 labelled terminals.
These have to be removed and placed in the orientation I have shown by the green loops in the picture.



Let me stress again that we need more confirmation before you connect up anything.

hi bob,
'assuming' the input wires (cyan coloured L1,L2,L3) are connected to the switch.
if they were removed and placed to the green L1,L2,L3 terminals and the metal strips were rearranged to match a delta arrangement (pictured),
this would essentially be a 'standard' connection bypassing the switch?

delta1.JPG

The motor appears to be "Star" only despite what is written on the name plate. The switch may have NO/NC and common terminals.

It appears that switch was designed to have 3 more leads going to it, the bridged terminals forming the centre of the star, in which case they could have been re-arranged to delta.

I'm wondering if that motor's been rewound and they decided not to bother bringing out the other ends of the windings?

based on the last two posts, does this mean the motor in its current state is not suitable for 240v output?
if this is the case what would be required to enable this to occur?

thanks
Ben

Originally Posted by bwah

based on the last two posts, does this mean the motor in its current state is not suitable for 240v output?
if this is the case what would be required to enable this to occur?

thanks
Ben

Then it would appear you either have to make do with about half power or you need to get the motor wired in Delta(assuming its in star now)

Stuart

Originally Posted by RustyArc

It appears that switch was designed to have 3 more leads going to it, the bridged terminals forming the centre of the star, in which case they could have been re-arranged to delta.

Correct - forgot about that.
Ben forget everything I have written up until now.

I'm wondering if that motor's been rewound and they decided not to bother bringing out the other ends of the windings?

Looks like it.

Ben that motor cannot be converted to delta at the junction box - it needs 6 wires (not 3) coming from the motor to reconfigure between ∆ and Y.

The common point inside the windings needs to be dug out and broken into 3 separate leads. Each of these leads then needs to be brought outside the motor and connected to an appropriate one of those red wires coming from the motor.

This is not a job for the faint hearted best to take it to a motor rewinder and get then

Now that we have seen the motor terminal box, you will have to do as Bob suggests,
if you want full motor hp either dig out the star point or take it to a motor rewinder to do it for you.
If you can live with 1/2 of the stated motor hp then you can wire it as is.

thanks for everyones input, very helpful
i will investigate having it re-wired in delta
keep u posted

Originally Posted by RustyArc

It appears that switch was designed to have 3 more leads going to it, the bridged terminals forming the centre of the star, in which case they could have been re-arranged to delta.

I'm wondering if that motor's been rewound and they decided not to bother bringing out the other ends of the windings?

bingo! wires have now been brought out and connected in delta. see image below

Originally Posted by BobL

bwah, the VFD must not have a switch between it and the motor connections as the VFD must do the switching otherwise you will damage both the VFD and the motor.
While the motor is running the VFD MUST not be disconnected from the motor.

If this is the case, can i leave the switch in the 'on' position and only turn the motor on via the VFD?

Delta220v.jpg

Originally Posted by bwah

bingo! wires have now been brought out and connected in delta. see image below

Great - did you do this yourself?

If this is the case, can i leave the switch in the 'on' position and only turn the motor on via the VFD?

If it was me I wouldn't risk it - if someone accidentally turns it off while it is running - not good
OR
Even if it's off but someone sees it as "on" and turns it of fand you then turn on the VFD - not good.

I would just wire the switch permanently on by moving the wires as shown
So each phase will have 3 wires attached to each other,
Delta220vx.jpg

Or At least gaffer tape cover the switch in the on position.

ok thanks again bob

and no i didnt bring the wires out.. i left that job for local motor rewinder

cheers

If space permits I'd think about adding a terminal block to directly connect the VSD to the windings, leaving the switch free to switch the VSD.

Stuart