Schaublin 135 - Help upgrading electrical system

[ballen]

Wiring looks good. But I don't agree with "S is wire number 10, on terminal 10, from c4, and V is wire number 10 from terminal 10 to motor."

On the circuit diagram, if you follow terminal block 10 from the motor up through the contactor, you will see that it is connected to R and not to S.

The goal here is to put SS L2/T2 in series with the S phase, because the S phase is NOT connected to the control transformer. If not clear, please ask.

In your shoes I would not trust that R/S/T are wired as shown on the schematic. Instead, I would turn off the lathe, find the two connections to the control transformer primary, then hold c2 shut by hand and use a continuity tester or ohm meter to identify which one of the three power feed wires coming into c4 was NOT connected to one of the two transformer primary leads. Alternatively, if the wiring paths are clear and visible, trace them.

PS: what is behind the green tab on the SS?

 

[marcsO]

Wiring looks good. But I don't agree with "S is wire number 10, on terminal 10, from c4, and V is wire number 10 from terminal 10 to motor."

On the circuit diagram, if you follow terminal block 10 from the motor up through the contactor, you will see that it is connected to R and not to S.

The goal here is to put SS L2/T2 in series with the S phase, because the S phase is NOT connected to the control transformer. If not clear, please ask.

In your shoes I would not trust that R/S/T are wired as shown on the schematic. Instead, I would turn off the lathe, find the two connections to the control transformer primary, then hold c2 shut by hand and use a continuity tester or ohm meter to identify which one of the three power feed wires coming into c4 was NOT connected to one of the two transformer primary leads. Alternatively, if the wiring paths are clear and visible, trace them.

PS: what is behind the green tab on the SS?

Ops well spotted, too much staring at that wiring schematic!

No clue whats behind that cover, will take a look tomorrow if needed?

 

[marcsO]

I cannot get access to the transformer without a fair amount of work, and as I have avoided having to do this so far would like to avoid it again if possible, so is there another way to test for feed S?
If I turned the lathe power switch on but not the power to the lathe could I test between S on the terminal bar and the middle input feed to d2. If that is connected I could then check from the lower middle output of d2 to the middle top feed of c4 and continue down to confirm which of 10/11 or 12 corresponds to S?

The other option is trial end error, if its not right and S is not connected through L2/T2 would this cause a problem with the SS or lathe?

 

[marcsO]

I turned on a1, continuity tested from terminal S to the top lower centre contact on c2 which from the schematic is where S terminates, got continuity, checked across the contactor for continuity by testing as I manually pressed in the contacts and got continuity, checked from c2 to c4 and got continuity and again manually checked the through continuity which all was good. Checked the output from c4 down to the terminals for high speed (10/11 and 12) and continuity occurred when tested on 11 which again agrees with the schematic.

Would you agree with this process and deduction? If so shall I connect 11 through L2/T2 as suggested?

 

[ballen]

Would you agree with this process and deduction? If so shall I connect 11 through L2/T2 as suggested?

Process and conclusion are correct. To be extra sure, you can additionally verify that there is NO continuity (or at least, much higher resistance) between R and 11 and between T and 11.

It should not be an issue if the S connection runs though SS L1/T1 or SS L3/T3. But if things do not work as expected, it is simpler for me to think about/analyse if both the R and T currents to the motor are controlled.

Green cover: just curious, no need to remove if you are feeling uncertain about it.

 

[marcsO]

Sometimes in life after hours of toil it would be nice if something worked first time - well sadly not here.....

So not entirely sure what's actually happening as don't want to leave it doing it's thing for long but it sounds like and looks like c4 when high speed is selected is oscillating in and out fast making an almighty noise - spindle not moving either.

Green cover looks like a moulding cover or a marking up plate as nothing under it I can see.

 

[ballen]

This is not unusual: getting electronics working is a one-step-at-a-time process. You get each bit working then add another bit.

The c4 oscillations are because when c4 engages power to the motor high speed windings, it draws enough current that the voltage drops, c4 drops out, and the process restarts.

How are the front panel "controls" on the soft starter set? You should have these configured for a long slow startup. The shutdown speed does not matter.

Please confirm that you have intercepted the 3 wires leaving c4 and going to the 3 motor high-speed windings, and inserted the soft starter into that path.

 

[marcsO]

On the front panel I have followed your instructions and they are set as:
For initial testing purposes, leave the top control of the soft start (ramp up time) at the current 5 secs. Put the middle control (start voltage) at the minimum setting. Put the third control (ramp down time) at the minimum value.

Confirm the SS is between c4 and the high speed motor windings, terminal 10, 11 & 12

 

[ballen]

Try increasing the ramp down time to 5 sec, to match the ramp up time. This is a bit of a "shot in the dark", but since an oscillation can trigger both "on" and "off", it makes sense to eliminate the possibility that it is somehow "triggering in the turn off direction" before trying other stuff.

If that doesn't make any difference, try ramping up the start voltage (middle dial). If c4 buzzes for a couple of seconds before you cut power, that's OK. Then increase the ramp time by 10%, and try again.

Basic idea is to explore that parameter to see if it helps, without damaging c4 in the process. I suppose you can also try shortening the ramp up time to see if that helps. Just go in reasonable size steps, paying attention not to damage c4's contacts.

PS: wiring as I can see it looks OK, but since I can't verify that the input wiring to the SS is coming from the output wiring of c4, or that the output wiring from the SS is going to the motor high speed winding, not possible to say for sure.

If this doesn't work as desired, my vote would be to bypass the high-current path of c4 (RST to UVW) and let the SS control the power on its own. Key point then is to leave the *other* connections to c4 in place. But since this strategy still relies on (part of) c4 to function correctly, not clear if it will improve matters.

Step by step.

 

[marcsO]

I have tried a range of slightly different settings, moving the ramp down to 5, increasing the start voltage etc and still lots of buzzing and on the odd occasion when the start voltage was set higher the system tripped and had to be returned to zero position on the carriage lever before it would select normal speed etc.

It would appear in its current wiring config it's not solving any problems sadly.

 

[ballen]

Should we try bypassing the high-current part of c4? Modified schematic below. Remember that the coil and aux contacts of c4 must be left in place - the Achilles Heel of this configuration.

PS: are there 'start' and/or 'run' LEDs on the SS, which indicate its control state?

If bypassing c4 as below does not work, then we will add a small relay to implement the missing NC contact on the SS, and bypass c4 entirely, including its coil and aux contact.

 

[marcsO]

There is a 'ready' and 'bypassed' LED on the front of the SS, the ready light glows when the lathe is turned on, don't know if the 'bypassed' LED comes on at any point as been more concerned not to leave c4 chattering for too long to check it.

 

[marcsO]

5000uF capacitor installed across the new rectifier as instructed..

 

[ballen]

5000uF capacitor installed across the new rectifier as instructed..
View attachment 406284

For the record (and the schematic) what is dc voltage on capacitor? On the brake when engaged? These are likely slightly higher than before

I like the white clip! In your shoes I would have put heat shrink tubing (black and red) over the bare wires of the capacitor.

 

[marcsO]

So just to check the suggested next action is to disconnect the feeds going into the lower top connectors of c4 and route these directly into the top of the SS keeping the S feed (number 11) running through L2/T2?

There are two cables to each of the connectors on c4 as there is a loop from each back to c3 so its a fair amount of fiddly work connecting these up as the access is tight due to the wiring being all routed and tied, if it's the next stage then will do so hence the check in here first.

 

[ballen]

So just to check the suggested next action is to disconnect the feeds going into the lower top connectors of c4 and route these directly into the top of the SS keeping the S feed (number 11) running through L2/T2?

Yes, this sounds right, assuming c1/c2 connect into the lower top connectors of c4 and not the lower bottom connectors.

Another way to do it: just add three jumpers that go between c4 lower top and c4 lower bottom. This bypasses the power switching part of c4. So wire c4/R to c4/U, c4/S to c4/V, and c4/T to c4/W.

Please study the schematic in post 311. That's the best description

There are two cables to each of the connectors on c4 as there is a loop from each back to c3 so its a fair amount of fiddly work connecting these up as the access is tight due to the wiring being all routed and tied, if it's the next stage then will do so hence the check in here first.

Yup, that's the next stage. I know how hard it can be to modify those connections, especially on the lower level.

 

[marcsO]

Sadly no joy with this either, same sort of noises with what looks like c4 oscillating fast, tried a few adjustments on the SS's three knobs but it actually got worse with a solid loudish buzzing at one stage when the ramp up and down were set to 5s and the centre was set at 9o/c, decided this was not worth testing further as something is not playing ball.

Used the jumper process you described which helped as would have taken a long time to remove and join all the leads in the restricted space available.

Rectifier VDC across the 5000uF capacitor when the brake is applied is 39.4VDC, capacitor is rated to 50VDC.

 

[ballen]

Sadly no joy with this either, same sort of noises with what looks like c4 oscillating fast, tried a few adjustments on the SS's three knobs but it actually got worse with a solid loudish buzzing at one stage when the ramp up and down were set to 5s and the centre was set at 9o/c, decided this was not worth testing further as something is not playing ball.

Used the jumper process you described which helped as would have taken a long time to remove and join all the leads in the restricted space available.

Rectifier VDC across the 5000uF capacitor when the brake is applied is 39.4VDC, capacitor is rated to 50VDC.

what is voltage across brake when brake applied?

I can not write a detailed reply now, but to get c4 out of the picture we will need a 230VAC. relay with at least one NC contact. I think we might be able to rewire c4 for this purpose. Details to follow soon…

 

[marcsO]

Would this fit the bill?

 

[ballen]

Yes, this fits the bill, but a much much smaller relay would also do. Before we go down this route, I was wondering if we could simply test the soft starter with the spindle motor and your RPC. I want to be sure that I understand how the SS works, and I'd also like to confirm that it can control/start the motor at high speed from your RPC.

To test the SS, remove the wire from c3-12 to SS-1. That should stop c4 from chattering, because it disables the "turn on" command to the soft starter.

After confirming this, put a long wire onto SS-1. Touching that wire to SS-1A (caution: these are at 240VAC!) should start the spindle motor in high speed mode. Could you see if that works?