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Deckel FP3NC 1986 soft start

noltelouis

Plastic
Joined
Feb 3, 2016
Good day all.

It has been a while since I last posted here, and now I have come for some advice.

I recently acquired a Deckel FP3NC in mechanically excellent condition. Had some electronic issues like non-functional screen etc., but mostly it is sorted now. I'm unfortunately forced to run this off a RPC. The one issue I can see is on spindle startup. I'm sure (after reading previous posts) that the in-rush current is to high, which causes a voltage drop and the control resets.

I have this idea to fit a "soft starter" between the motor contactor and the motor. Just to clarify, not a VFD, but a rather a device on which you can adjust the "ramp up" time of a 3 phase motor. It works by chopping the sine wave with thyristors and gradually switches to full supply voltage over the specified time.

I would like to know if anyone has tried this? And also if there is any motor feedback, like current, speed, etc. being fed back into the control that might conflict with my idea?

See attached the youtube video on the device explanation.


Thanks for lending me your ears (or eyes for reading)!

Louis.
 
I think you’ll need to bypass the soft starter during gear shifting. The motor won’t turn enough or at all to allow gears to engage, and the resistors switched in while jogging the motor won’t play nice with the starter.
 
I was always wondering about the jogging of the motor on gear shifts. How exactly does that take place? I have an FP3A that someone retrofitted with a VFD. I doubt the VFD jogs the motor.

The resistors that you mention, are they there to reduce motor voltage upon gearshift to reduce the motor speed?

I'm also not thinking to increase the startup time by much, but as little as 2-3 second ramp-up just to reduce the startup current.
 
Think that Rich is dead on here....
The shifting works like this.....
When a gear is selected, the spindle is stopped (if already running) with brake applied.
The spindle is jogged (K1 or K2 for direction and K3 which ties R1, R2 and R3 in series to the motor slow speed winding (star)).
The on time is short more a pulse and at the same time the main motor brake is released.
The cycle repeats for i believe 4 cycles or motor pulses, then the direction is reversed (k1,K2) and the pulse cycle is repeated...
Then the direction is reversed once again and continued for an additional 4 cycles....
while the spindle is cycling the shift motors (M5 M6 & M7) have power applied and are trying to shift the gear selectors (3). If the correct gear is attained as indicated by the
micro switches running on cams of the shift selector shafts , the shift cycle is halted. Further is one shift shaft finds its correct position while the remaining 2 are still "hunting" that shift motor where correctly positioned will be disabled....

If all the switches (3 / shaft) fail to indicate correct gear position the machine will go into an E-stop fault after completing the third reversal cycle of the spindle motor.....

Most shifting issues can be helped by cleaning the motor relay contacts. The low voltage used in the jog cycle needs good make up on the relay contacts to work
well...
There is a truth logic table for the spindle ear selection/switch condition on sheet 22 of the first section of the "Orange" book.
An additional note: Be sure that you do not have have the "Non-Generated" leg from your rotary feeding the control. Should check the print but think the control uses
L1 and L3....

Goes without saying that going for CNC a machine and what ever else your shop is carrying, maybe its time to improve your power supply to be in concert with that fine mill.....
My bet is that your machinery fleet will only get larger having greater power needs , ..Think Phase Perfect....Its a real answer for a full shop power solution.
Cheers Ross
 
Last edited:
Thanks for that detailed description Ross!

So if not doing a gear change, where is the supply for K1 and K2 coming from or going to? There must be another relay then besides K3 to bypass the resistors? Or would K1 or K2 feed K3 N/C and on gearchanges switch through the switched N/O to route through the resistors?

I have some schematics, but the quality is so poor that I can’t even begin to try and desypher it!

I’m asking this as there must be a different location then to add the soft starter in order to bypass the gear change circuit?
 
Ok here you go...picture worth lots of words.....

full


Cheers Ross
 
Now that I can work with!! Thanks Ross, that will help me loads!

So looking at it, for argument sake if I fit 2 soft starters, one between the motor and K4 and one between the star/K3 junction and K5, it will leave the gear change circuit unaffected?

1659471724022.png


I will investigate further and see what I come up with.

Once again, thanks for the valuable info!

Louis.
 
May wish to do some testing.....Be sure your wire size is overdone...Bigger is better....
Then run the machine to see if you really need the soft start for the low motor speed....
Often the drop out of the control happens when running in the upper speed ranges.....with the high speed motor winding.
Cheers Ross
 
Thanks for all the input! I will really take them all into consideration!

BTW, are there any people here that runs these specific Deckel NC on RPC? I have read that the Phase Perfects are great, but to get utility power will be cheaper than to buy one of those (where I live anyway!) So how successful can they be run on rotary converters? I know the load balances will always be an issue.

Thanks again!

Louis.
 








 
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