Fortuna band-knife splitter trips internal breaker

[Matt S]

My Fortuna UA has an annoying habit of tripping the breaker for the knife motor when splitting full-width pieces. The blade is plenty sharp -- it makes a beautiful split for an inch -- but then it pops the breaker and everything stops. The leather doesn't appear to be hanging up on anything (I've split a lot of leather with this machine), just certain leathers at full width tend to stop the machine in its tracks.

I've tried reducing and increasing the spring tension on the feed rollers. No difference. The drive motor is in "slow" mode, and on the low gear.

The breaker trip current is adjustable. It's correctly set at what the manual suggests for 440v operation. I'm running the machine from a self-built static converter, using the knife and feed motors reconfigured in tapped-centre star mode to smooth out the second and third phases, giving roughly 250, 225 and 205 volts. I wonder if I need to/should/could increase the trip current to what the manual suggests for 220v operation? Does the manual mean what we'd understand as delta/star when it mentions 440/220v operation for a 3-phase machine? The motor's pretty beefy, I expect it would survive a couple minutes of drawing a couple extra amps.

I know that several of our members have done or do operate these classic machines. Have any of  you encountered such an issue? Could I get away with turning the breaker trip current up?

[TonyRV2]

As a former engineer and electronics professor, this is not a straightforward question to answer without having access to the manual and wiring instructions. I did look online for something but to no avail. In my experience when a machine can be wired for either 440 or 220 3 phase, the manufacturer is referring to the mains voltage. I also assume by static converter you're referring to a single phase to 3 phase converter that's delivering the 220 (roughly) 3 phase that you need for the machine.  All of that said, I believe that your breaker should therefore be set up for 220V operation since that's what your delivering to the motors. I am concerned though about the phases being unbalanced, 250, 225 and 205 respectively. I would think that this at the very least is going to cause some unwanted vibration in your motor, but first things first.

[480volt]

 

I would defer to the manufacturer’s suggested setting. If you’ve changed the voltage a motor runs at, you’ve changed the amount of current it will draw. What device are you are changing the settings on?

[Northmount]

Have you updated the motor connections for 220V?  Normally the interior wiring of the motor needs to be changed for different voltages.  And at 220V, the motor will draw roughly twice the current as it does when wired for 440V.

Have you got the wiring diagrams for 220V and 440V to compare where the connections need to be changed?

Tom

 

[RockyAussie]

Neither of mine ( Albeko and Komoga) have ever tripped off but on a very wide and hard split i have had the splitting stop due to the belts slipping. That is a super rare occurrence but may just help you some here perhaps.

 

[480volt]

Any chance of a wiring diagram on this machine? On US spec equipment (which this is not) 3-phase motors would typically be controlled by a motor starter for each motor. The overload heaters, or current sensing devices would protect protect each motor from an overload condition. Any associated circuit breaker would be responsible for over-current protection, such as direct short. It sounds like you’ve already reconfigured the motors for low voltage, now you have to mess with the overloads.

Also, static converters are inferior to RPCs for powering machines, they really just give you the ability to get a 3-phase motor started off of single phase power. Better to build an RPC from a used motor, the motors in your tool won’t care about the phase angle.

[Matt S]

On 10/26/2019 at 3:00 PM, TonyRV2 said:

As a former engineer and electronics professor, this is not a straightforward question to answer without having access to the manual and wiring instructions. I did look online for something but to no avail. In my experience when a machine can be wired for either 440 or 220 3 phase, the manufacturer is referring to the mains voltage. I also assume by static converter you're referring to a single phase to 3 phase converter that's delivering the 220 (roughly) 3 phase that you need for the machine.  All of that said, I believe that your breaker should therefore be set up for 220V operation since that's what your delivering to the motors. I am concerned though about the phases being unbalanced, 250, 225 and 205 respectively. I would think that this at the very least is going to cause some unwanted vibration in your motor, but first things first.

It's quite common for phase converters to run with a voltage drop per phase. 10% per phase is considered acceptable. I've never run this machine off "real" 3-phase but I imagine that the vibration I get, though not huge, is a little more than it would be on a "real" 3ph supply. It's worth the saving over having a 3-phase supply installed!

22 hours ago, 480volt said:

I would defer to the manufacturer’s suggested setting. If you’ve changed the voltage a motor runs at, you’ve changed the amount of current it will draw. What device are you are changing the settings on?

The thermal overload breaker dedicated to the knife motor is the one that's tripping and I'm considering adjusting. The problem is that the manufacturer's manual is a little vague on this subject.

19 hours ago, Northmount said:

Have you updated the motor connections for 220V?  Normally the interior wiring of the motor needs to be changed for different voltages.  And at 220V, the motor will draw roughly twice the current as it does when wired for 440V.

Have you got the wiring diagrams for 220V and 440V to compare where the connections need to be changed?

Yes I've reconfigured the motor wiring boxes for the two largest motors (knife and feed) from delta to star, so I could tap the centre point of the star out to the phase converter. The machine's been running fine for 9 months, this is the only real electrical issue I've encountered. There are no separate wiring diagrams for 220v and 440v operation -- all four motors in this machine are 3ph, plus a transformer for the switchgear and ancilliaries with a multi-tap primary. This was originally run off one of the phases but I gave it its own dedicated supply.

19 hours ago, RockyAussie said:

Neither of mine ( Albeko and Komoga) have ever tripped off but on a very wide and hard split i have had the splitting stop due to the belts slipping. That is a super rare occurrence but may just help you some here perhaps.

Thanks Brian. I realise that your machines are slightly different from mine but it could be that I have mine setup with tighter belts that you -- so that when hitting a wide, hard piece that would stall my motor or cause its breaker to trip would simply cause your belts to slip.

5 hours ago, 480volt said:

Any chance of a wiring diagram on this machine? On US spec equipment (which this is not) 3-phase motors would typically be controlled by a motor starter for each motor. The overload heaters, or current sensing devices would protect protect each motor from an overload condition. Any associated circuit breaker would be responsible for over-current protection, such as direct short. It sounds like you’ve already reconfigured the motors for low voltage, now you have to mess with the overloads.

Also, static converters are inferior to RPCs for powering machines, they really just give you the ability to get a 3-phase motor started off of single phase power. Better to build an RPC from a used motor, the motors in your tool won’t care about the phase angle.

I'll get the wiring diagram scanned. This, I'm sure you realise, is a German-manufactured machine from the 60s or 70s, intended for running directly from a 3ph supply in an industrial environment. There are no motor starters installed -- all four motors are controlled by multi-pole contactors as part of the original switchgear. I only have single phase available in my workshop and the current consumption is well within the capabilities of a standard 13A plug so I built a simple static converter. The converter contains the starter -- a simple arrangement with a large capacitor and a time delay relay. IIRC the TD relay switches from delta (start) to star (run) too. In use I press the "go" button on the splitter and then apply power to the phase converter. It's not the neatest solution but required fewer changes to the machine and works well.

The motor associated with the breaker that keeps tripping turns the band-knife. I suspect that the wider, harder splits are putting a little more strain on the motor than usual and as you say the breaker needs adjusting. However I wondered if anyone else who runs a splitter has encountered a similar situation before I risked the life of a good motor!

I'll be honest with you, until I converted/adapted this machine early this year I knew SFA about 3 phase. However having read a decent book on the subject and many articles I realised that the fact this machine requires 4 different motors to run simultaneously means that the largest of the motors will act as a RPC for the rest. Or, to paraphrase, the more motors are run simultaneously from the same converter the smoother the phases.

[MikeRock]

Have you got an Amprobe?  Current measuring goodie, probe arms clip around the wire and measure current used.  Check each leg, first on the troublesome motor, then the incoming lines.  Might find some clues.

I'm having trouble today with a three phase motor on a South Bend Heavy 10 lathe, virtually the same issues.