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rustyovali
10th Feb 2019, 05:38 PM
Hi all,as the title says,a large piece of German machinery followed me home this week in the form of a 1970 Mossner Rekord SSF420 vertical bandsaw,3 phase of course.
378053.I've removed the motor and upon inspection of the electric motor plate I at first thought it was 2.2kw 415 volts 5 Amps 3 phase delta only.
378054On the underside of the connection box cover there was the usual diagram to change the connections to star,does this configuration also change it to low voltage ie 240volts 3phase?
On the other 2 other 3phase machines I have the motor plates list various voltages and amps,So choosing a VFD was relatively easy.
I changed the terminals to star and have temporarily connected it to the VFD I use for my shaper and it runs fine{no load},at the correct rpms at 50Hz as verified with a tacho.My question is if the plate states 415v3ph draws 5amps,is there a formula to calculate how many amps will it pull on 240v 3ph? and therefore which VFD? I have a Huanyang on the shaper and a AC tech on the mill,so maybe its time to give a Powtran a go but what size? and what model.This band saw has a hydraulic/gravity power feed system so I'd like to keep as much of the original horsepower as possible.
Thanks,Nick

Michael G
10th Feb 2019, 07:43 PM
From memory, a 3 phase motor should be wired in delta for use on a VFD. Confirmation someone?

Michael

BobL
10th Feb 2019, 08:00 PM
From memory, a 3 phase motor should be wired in delta for use on a VFD. Confirmation someone?

Michael

Not necessarily - it should be wired to fit the voltage that develops its full power.

It just so happens that if a 415V Y wired motor is converted to ∆ it will run on full power on 240v.
If it is 415V ∆ then you are screwed because converting it to Y means it will only develop full power at ~800V.

In both cases it will run BUT if you try and run it under load you will eventually kill the motor - Like I did on a compressor.
The compressor came with a 4HP 415V ∆ that was burnt out so ai replaced it with a $30 5HP 415V ∆ (makes about 2.5HP on 240V 3P) and it lasted for about 6 months.

There is no need to worry about current - just work on power. If it's a 2.2kW motor then that's 2.2kW whether its 240 or 415V.
Then get a VFD that is rated for that power.

For something like that BS I'd for a Powtran PI160 model. See attachment
PI160 2R2G1
Im using the 1.5kW versions on my Lathe and Drill press.

RustyArc
10th Feb 2019, 08:02 PM
A 415V star motor can be run at 240V delta, but the nameplate shows this to be a 415V delta motor, so it won't perform to spec on 240V, and changing it to star will make it even worse.

[Edit] Beaten by the VFD expert :)

rustyovali
10th Feb 2019, 08:12 PM
A 415V star motor can be run at 240V delta, but the nameplate shows this to be a 415V delta motor, so it won't perform to spec on 240V, and changing it to star will make it even worse.

[Edit] Beaten by the VFD expert :)
Thanks RustyArc ,Bobl and Michael G for the replies.So it looks like its new motor time.I guess there are 2 options
Option 1 3phase dual voltage motor+ vfd or
Option 2 1 phase motor
I'm leaning towards op1 what do you guys think?

rustyovali
10th Feb 2019, 08:38 PM
Hi BobL,just saw the attachment,thanks.As the motor plate says 415 delta,{see photo in first post} Do you know if a PI 160 2R2G3Z uses single phase input? or is it 3phase in,3 phase out?

BobL
10th Feb 2019, 08:52 PM
Hi BobL,just saw the attachment,thanks.As the motor plate says 415 delta,{see photo in first post} Do you know if a PI 160 2R2G3Z uses single phase input? or is it 3phase in,3 phase out?

G1 models are 240V SP in and 240V 3P out.
G2's are 240V P in and 240V SP out.
G3 are 380 3P in and 380V SP out.

I have not seen any 240V SP in and 415V 3P out, in the Powtran range, even amongst their new models (150 and 500A's)