Running 12" BAO/S Planer Thicknesser with inverter drives

[MilesH]

Thanks. Good ideas there. I appreciate your advice.

My lathe is a Myford (254 plus). Single phase!

Miles

 

[Myfordman]

My pleasure Miles

A mere Myford ML7RB but with a VMC sitting alongside - Inverter driven of course!

 

[GK1]

Just to add my solution. Sedgwick MB with 4kW 415v dual voltage cutterblock motor and two-speed Dahlander motor on the feed (like yours I think).

Cutterblock motor is configured for 240v 3-phase and runs off a 4kW inverter - direct connection to the motor terminals.

Feed motor is always set to high speed on the speed selector and is fed from a 1.5Kw inverter set to output 29Hz, which runs the feed at the original 'low' rate. I live with single speed feed. Direct connection to the two speed switch terminals in the Sedgwick electrical box.

I suppose I could use the inverter variable output to vary the feed speed but I never do.

Independent dual push buttons to start the inverters. Works well, nice gentle run up and stops within 10 seconds.

edit: I'd have to check my notes but I believe this set up delivers the expected voltage to the feed motor, no need for step ups. The cutterblock motor runs at the rated output of course but you will need the 240v connection ability.

 

[Myfordman]

Just to add my solution. Sedgwick MB with 4kW 415v dual voltage cutterblock motor and two-speed Dahlander motor on the feed (like yours I think).

Cutterblock motor is configured for 240v 3-phase and runs off a 4kW inverter - direct connection to the motor terminals.

Feed motor is always set to high speed on the speed selector and is fed from a 1.5Kw inverter set to output 29Hz, which runs the feed at the original 'low' rate. I live with single speed feed. Direct connection to the two speed switch terminals in the Sedgwick electrical box.

I suppose I could use the inverter variable output to vary the feed speed but I never do.

Independent dual push buttons to start the inverters. Works well, nice gentle run up and stops within 10 seconds.

edit: I'd have to check my notes but I believe this set up delivers the expected voltage to the feed motor, no need for step ups. The cutterblock motor runs at the rated output of course but you will need the 240v connection ability.

If that works for you then great but I suspect that your feed motor is only getting 240v 3 phase rather than the 415 it is designed to get. So 1/root3 of the voltage and therefore 1/root3 of the current as well gives 1/3 of the power to feed motor.
The inverter may well try and compensate to try and maintain the shaft speed by upping the current to a certain extent if you are using Flux current control or Vector control mode in the inverter even then I suggest there will be less than 1hp being delivered by the feed motor.

 

[GK1]

You could be right. The feed motor is designed for 400v in star or delta.

My solution is based on the linked article, which says "a 400V x 50Hz Motor will operate normally at 230V x 29Hz, just at two thirds the speed (eg. 1000rpm instead of 1500rpm)."

I *think* but stand to be corrected, the inverter will adjust the current so the motor still supplies rated output.

What I do know, is that I have used my planer like this for sometimes an hour or so at a session and the feed never stalls or complains.

https://inverterdrive.com/HowTo/240V-Su ... -AC-Motor/

 

[MilesH]

If you only need the lower speed, you only need the power for that speed to maintain the same torque. Effectively, it's variable power constant torque switching. Isn't that right? The feed motor on the Wadkin is rated at 1/2hp at the high speed and 1/4hp at the lower.

 

[GK1]

Yes it's straightforward star/delta, I was confusing it with my spindle feeder!

Sorry I don't know about the mathematics. I know it works well for me, as I said, I can live with the lower of the two feed speeds. I looked at the 240 to 415 inverters and was on the brink of buying one, but thought this seemed like a good enough method and isn't doing any electrical harm (as far as I can see).

I run my 415v spindle feeder motor in the same way, that is Dahlander, off a 240v 3-phase inverter, always set to high speed but with reduced frequency to maintain the low feed rate and it works perfectly well.

I shied away from the 240 to 415 inverters on the grounds of high cost and being tied to one vendor only.

 

[MilesH]

It does seem a reasonable way to go for the BAO/S

Cutterblock motor: rewire to Delta and use a 3 hp 240V inverter.

Feed motor: Use a separate 240V inverter set to 29Hz so that the motor will run at 1000 rpm and 500 rpm (instead of 1500 and 750) depending on the position of the 2 way switch. This will give base feed rates of 3m and 6m a minute instead of the original 4.5m and 9m.

 

[Joshjosh]

It does seem a reasonable way to go for the BAO/S

Cutterblock motor: rewire to Delta and use a 3 hp 240V inverter.

Feed motor: Use a separate 240V inverter set to 29Hz so that the motor will run at 1000 rpm and 500 rpm (instead of 1500 and 750) depending on the position of the 2 way switch. This will give base feed rates of 3m and 6m a minute instead of the original 4.5m and 9m.

Hi I’m looking to do a similar thing and wondered if you tried this and whether it worked?
Thanks josh

 

[MilesH]

Hi Josh,

My BAO/S is still in pieces... I bought a new 240V 3ph motor for the cutterblock to boost the power a bit. Still planning on using the original feed motor though. Ongoing thread on my BAO/S here: wadkin-12-bao-s-planer-thicknesser-project-t114281.html