Colchester Triumph 2000 – Bridge Rectifier

[danielcvParticipant @danielcv]

Hello,

anyone knows where I can get this, or a compatible bridge rectifier for my Colchester Triumph 2000?

Thanks in advance,
Daniel

[Pete RimmerParticipant @peterimmer30576]

I’ve got a couple of types to choose from here in Kent. What current does it need to deal with?

[danielcvParticipant @danielcv]

It is not specified, but as far as I imagine it would be 35A. Perhaps anyone knows exactly the specs?

[Pete RimmerParticipant @peterimmer30576]

Unlikely unless you have a DC drive motor. That would provide several kilowatts.

I have some 10A ones here if you’re stuck I’ll go and check.

[danielcvParticipant @danielcv]

Thank you. But I pretty sure I need 35A. I tought I would buy a KBPC3510 – anyone can confirm if this one fits ?

[MacolmParticipant @macolm]

Should not be difficult to get. Read characteristics carefully! The rating is conditional in keeping the case temperature to the specified value.

https://www.bitsboxuk.com/index.php?main_page=product_info&cPath=140_141_146&products_id=2751

[danielcvParticipant @danielcv]

that one has the same specs as the KBPC3510 as far as I can see… I am lost, no idea which one really

[Julie AnnParticipant @julieann]

It’s an odd looking package for a bridge rectifier. It’s not clear if the writing means that the input is 220VAC or that the +/- terminals are the input, in which case it probably isn’t a bridge rectifier.

Julie

[FulmenParticipant @fulmen]

It’s either a rectifier or the world smallest VFD 🙂

[Robert Atkinson 2Participant @robertatkinson2]

It certainly doe not look like a 35A bridge rectifier. I’d expect a heatsink for a start. As Pete has said 35A at 220V is a lot of power. Also none of the wiring diagrams in Colchester Triumph 2000 manuals i can find online show any bridge rectifier.

We need more information:
What type of motor is fitted to your lathe?
What is this item connected to?
What colour if any are the wires connecting it?
Can you post a picture showing it’s clocation and more of the electrics?
Why do you think it’s faulty? (I can see one terminal looks a bit over heated).

I looks more like a terminal block that has been broken off something else. Maybe a contactor or solid state relay.

Robert.

[WingoParticipant @wingo]

Does the motor have a brake fitted? Is a brake diode pack ,often found in the motor terminal box?

[danielcvParticipant @danielcv]

Thanks a lot. On monday I will get pictures of the specs and electrics. The machine is in Africa and I am trying to help some friends there.

[danielcvParticipant @danielcv]

For now, just to say, yes it has a brake and the brake doe snot work anymore.
These are the photos I have now, but on monday I get better ones

[WingoParticipant @wingo]

I think you will find that a 220v supply is switched by the motor contactor so that the dc brake is powered via the diode block. That dc supply energises that brake release coil, opening the brake allowing the motor and lathe to rotate.

When stop is selected the contactor contact opens, removing the brake power, applying the brake.

Hope this description helps.

[danielcvParticipant @danielcv]

I understand partly. So, the device that is damaged (first two photos in this thread) is a bridge rectifier, which normally would close the brake when stop is selected? Right now, the brake does not close. So the motor runs loose after stop is selected.
If this is correct, then the KBPC3510 would do the job ?

[WingoParticipant @wingo]

Normally brakes are fail safe, no power brake closes. I.e. spring close, power open.

If no braking then I would look at the mechanics of the brake assembly.  Broken spring?

[peter1972Participant @peter1972]

Is there a small printed circuit board under that black cover?

If so, can the cover be removed?

[WingoParticipant @wingo]

Just another note  if it is a brake pack they can often be just a single diode or diode pair not a full bridge. The brake coil just needs some lumpy DC ish power to operate, not a perfect stabilised DC!

[danielcvParticipant @danielcv]

Normally brakes are fail safe, no power brake closes. I.e. spring close, power open.

I thought just the opposite is happening: The diode got into short-circuit, so the brake gets power all the time => brake is open.

[Bob WorsleyParticipant @bobworsley31976]

Is there a physical brake? If so then the motor spindle won’t be able to be rotated. Rather doubt it. In that case could be a DC injection brake when the lack of a heatsink is ok, only used for a couple of seconds each time. And the motor spindle willl be free to rotate.

Put the lathe in gear and try to rotate the chuck, that will tell you if you have a physical brake or not.

 

 

[danielcvParticipant @danielcv]

The lathe in gear, it rotates freely.
so now I am confused with the bridge rectifier theory…

[Pete RimmerParticipant @peterimmer30576]

Having no experience with the Triumph I had to look online and it seems that some models had a physical hydraulic brake and apprently some had an electrically operated brake.

There are several ways to brake a lathe.

Physical friction brake that can take many forms. I had a Bantam which had a rod actuating a brake block on the vee of the belt pulley. Some have a drum or a disc either air actuated or hydraulic. Some Colchesters had the lever-operated clutch and rake combined.

Electrical friction brake either spring operated and electrically held off (like my HLV) or electrically actuated. A DC actuator could allow for variable braking effort

Applying a resistive load across the motor. You might use a rectifier and heating element to achieve that but I don’t know why you would and the 240V rating makes that particular one under-specified.

Applying DC voltage into the AC motor windings. This creates a fixed electical field which acts against the spinning field of the rotor causing it to slow rapidly. This one makes the most sense in your friend’s case IMO. Usually DC braking is done over a very short duration because it causes the windings to heat up. You might apply a large load to brake the motor downa and then a small DC load to hold the spindle.

Really it’s all guesswork until someone with knowledge comes along. One benefit you have is that you have the wiring schematic code right there in the picture. It might pay you to message Tony at lathes with that code and see if he has the diagram within his vast library.

[peter1972Participant @peter1972]

Has the item been tested with a multimeter?

From a wiring diagram, there may be a resistor in there as well as a bridge rectifier.

[danielcvParticipant @danielcv]

Yes it makes sense the way of applying DC voltage, to the motor or to brakes. As the device as the DC marks, there are not much more places where DC makes any sense at the lathe. Tony at Lathes ? Where can I find him exactly ?

[danielcvParticipant @danielcv]

I found the manual and here is the wiring diagram. But I do not understand it.

[Author]

Posts