Holbrook c Model 10 Lathe electrical problems

[Ray Millington]

Hi All,
When I retired as a toolroom engineer I purchased from my employer a Holbrook model c no10 lathe also a Bridgeport miller obviously both are 3 phase electrics so
I purchased a Transwave inverter to give me the 3 phase supply, the 3 phase was connected to both machines the Bridgeport runs perfectly using its original control board and buttons however I cannot get the Holbrook to run, this is what happens,
1 When I switch on the lathes original mains contractor and press the start button on the control panel the start relay closes,
2 When I then use the forward and reverse lever on the apron the motor should start it does not have checked the forward and reverse contacts that are activated by this lever and the are sound and in good condition and the wires are good and the screws are tight,
3 If I manually press in the forward and reverse relays in the control panel the motor runs.
I cannot believe that both relay coils have failed
I have tried changing the 3 phase supply wires no difference
I have confirmed that the lathe was built during the second world war the electrics are all original,
II am no electrician so any help would be greatly appreciated
Many Thanks Ray.

 

[moonlight machine]

Since you have no location listed I can only guess you are on the island across the pond? Are you running it on the same voltage as your employer did? Sounds like a control transformer issue. I had nothing but trouble with the electrical bits on my C13, the contacts in the base under the headstock were out of this world. I swapped out the giant 3 speed motor for a 5hp 3 phase and a VFD, a big improvement in my opinion.

 

[Ray Millington]

Since you have no location listed I can only guess you are on the island across the pond? Are you running it on the same voltage as your employer did? Sounds like a control transformer issue. I had nothing but trouble with the electrical bits on my C13, the contacts in the base under the headstock were out of this world. I swapped out the giant 3 speed motor for a 5hp 3 phase and a VFD, a big improvement in my opinion.

Yes sorry I am in the UK ,
Not sure but I don't think there is a control transformer used on the Holbrook.
Originaly it ran on a true 3phase supply the Transwave is 2 phases with the third phase being generated
by large capacitors to give the third phase,
I am assuming that the control voltage for the relay colts is one of the single phases supplied?
regards Ray.

 

[dalmatiangirl61]

What voltage are the coils? Have you confirmed they are getting correct voltage?

Make sure the coils are NOT being powered by the generated leg.

 

[JST]

Change the mains wires around so that all the controls are run from the "pass-through" wires, and not from the generated leg.

That may help considerably, as the generated leg is not very stable even when generated with an idler motor. With the fancy phase shift system, the small load of the controls may not get enough voltage, possibly because the phase shift was not enough.

With capacitors making the phase shift, the amount of loading can affect the phase shift. A light load may not get nearly enough to have enough voltage difference.

 

[Hopefuldave]

If it's like the C13 all the relay coils are 415v, and there's an additional swith on the 3-speed lever (opens when ther lever's pulled out of the detent).
So you have 3 relays thst all need 415 to their coils - forward and reverse (the two mechanically interlocked ones, controlled by the contacts at the tailstock end)) and coast-while-changing-speed which removes power (but not control voltages) from the forward and reverse relays so the motor isn't energised when switching windings.

Is the Transwave outputting 240v? the Holbrook's NEED 415v both for the relays and for starting the motor in the high speed.

Assuming it produces 415v, is the Transwave a static convertor, or does it have an idler motor? if static, that'll be your problem, add a decent sized (4-5HP) idler.

Dave H. (the other one)

 

[Ray Millington]

If it's like the C13 all the relay coils are 415v, and there's an additional swith on the 3-speed lever (opens when ther lever's pulled out of the detent).
So you have 3 relays thst all need 415 to their coils - forward and reverse (the two mechanically interlocked ones, controlled by the contacts at the tailstock end)) and coast-while-changing-speed which removes power (but not control voltages) from the forward and reverse relays so the motor isn't energised when switching windings.

Is the Transwave outputting 240v? the Holbrook's NEED 415v both for the relays and for starting the motor in the high speed.

Assuming it produces 415v, is the Transwave a static convertor, or does it have an idler motor? if static, that'll be your problem, add a decent sized (4-5HP) idler.

Dave H. (the other one)

Hi All,
Thank you for the replies ,
When I switch on the power from the 3 phase inverter and press the start button on the console the start relay is energised but the motor will not start from the control lever however if I manually press either the forward or reverse contractors in the the motor runs as I said I am no electrician but does that not indicate that the 3 phase supply is ok?
From Hopefull Daves comment it would appear that the relay coils need 415v and as that is not available until the motor is running that maybe is the problem.
I have the electrical drawings for the lathe but they do not indicate the coil voltages,
The confusing part for me is that the start relay does energise I cant imagine that's on a different supply voltage my next step is to get the inverter checked out thanks again for the replies my model steam engine and model aero engines will have to wait.
Regards Ray.

 

[SAF]

Put a voltmeter across all three combinations of the supply leads, and report the the three different voltages that you measure.

 

[Ray Millington]

Put a voltmeter across all three combinations of the supply leads, and report the the three different voltages that you measure.

Thanks for the reply SAF,
I will check the voltages and reply a s a p thanks Ray.

 

[beckerkumm]

There is a very active Holbrook group at Groups I. O. You might want to check that out as there are very knowledgeable people on everything Holbrook there. Dave