Help on fault finding on a C3-31 Hammer combination machine

[OMLCNC]

Is the MCB332A which is tripping running the transwave and have you checked the output of the transwave as cack 3 phase into your machine will cause it to play up as various control bits are powered by single phases.

Nick I have a Wadkin planer and a Speed Sander I run off the transwave and they are both running fine.

[m_c]

Nick I have a Wadkin planer and a Speed Sander I run off the transwave and they are both running fine.

It may be down to how each machine is connected. Do you have this machine connected, so the two legs (2 & 3) that power the control circuits, are connected to the non-generated leg on the converter?

With most common single to three phase converters, two legs are supplied directly from a step-up transformer, then the 3rd leg is generated using purely capacitors (in the case of static converters), or by a combination of idler motor and capacitors (in the case of rotary converters).
If you connect one of the control legs to the generated leg, then it is very likely to sag under motor starting loads, which would explain your symptoms. If you have had it connected this way, then there is a possibility that converter is the problem, which is why we're asking about voltages. It could be the converter has either developed a fault (some will try and boost the voltage under high load conditions), or it could just be a combination of capacitors getting a bit weaker as they age, a bit extra load on the motors, and the cold weather making things a bit sluggish, that have pushed things to the point the problem has become apparent.

And if your other machines are connected so their control circuits are powered from the non-generated legs, it would give the impression the convertor is working fine, as although the generate leg would sag while starting, you probably would not notice any difference unless really pushing the machines to their maximum loads.

So in short, check what voltages you're getting into the control, especially the voltage at the transformer that is supplying the 230V for the controls.

[OMLCNC]

It may be down to how each machine is connected. Do you have this machine connected, so the two legs (2 & 3) that power the control circuits, are connected to the non-generated leg on the converter?

I will find the Transwave manual and have a look, do you mean L2 and L3 on the drawing?

With most common single to three phase converters, two legs are supplied directly from a step-up transformer, then the 3rd leg is generated using purely capacitors (in the case of static converters), or by a combination of idler motor and capacitors (in the case of rotary converters).
If you connect one of the control legs to the generated leg, then it is very likely to sag under motor starting loads, which would explain your symptoms. If you have had it connected this way, then there is a possibility that converter is the problem, which is why we're asking about voltages. It could be the converter has either developed a fault (some will try and boost the voltage under high load conditions), or it could just be a combination of capacitors getting a bit weaker as they age, a bit extra load on the motors, and the cold weather making things a bit sluggish, that have pushed things to the point the problem has become apparent.

And if your other machines are connected so their control circuits are powered from the non-generated legs, it would give the impression the convertor is working fine, as although the generate leg would sag while starting, you probably would not notice any difference unless really pushing the machines to their maximum loads.

So in short, check what voltages you're getting into the control, especially the voltage at the transformer that is supplying the 230V for the controls.

So using test meter on Hv setting I get 237v on a workshop socket outlet (just checking I'v got the correct range) then 160v over the low side of the transformer and 364v over the high
side. 160v seems too low?

The contacts made well some times and chatterd others. Going to look for manual for Transwave.

[EddyCurrent]

I was taught that 'rule' no1 when fault finding is, "check the supply"

A contactor needs more voltage to close than it does to retain but 160v is only about 70% of required, plus, as the motor applies load it is going to drop a lot further.

The other to watch is phase rotation, you don't want to be swapping phases around willy-nilly otherwise the motor direction could reverse.

[magicniner]

You should test a supply in both no load conditions and with a load of a significant percentage of that with which you are having problems.

[m_c]

160V does seem low. It's not unknown for transformers to fail, but as Nick says, check what happens to the voltages when you try starting the motors. Test the high and low sides to see what happens.

Also test between the other legs when starting, to see if you any sag more.

[EddyCurrent]

You should test a supply in both no load conditions and with a load of a significant percentage of that with which you are having problems.

No desire to be pedantic about this but,
That's not what I meant about 'rule no1' , I meant if there was nothing there when you pressed "start". In other words, "check there is the required voltage at the machine".
The quality of the supply comes later after pressing "start" does it's job.

[OMLCNC]

Sorry but I made a mistake when testing the voltage on the transformer, wrong connections.
Now get readings of 464v and 260v.
Also get 242v over the contactor.

What to check next?

[magicniner]

No desire to be pedantic about this but,
That's not what I meant about 'rule no1' , I meant if there was nothing there when you pressed "start". In other words, "check there is the required voltage at the machine".
The quality of the supply comes later after pressing "start" does it's job.

If I'd been referring to your suggestions I'd have quoted you.
When looking for the source of a fault in a 3 phase electrical system where components such relays and actuators are commonly run from one phase with different components running from different phases then if you don't check what you have before applying any load at all then you can make things harder for yourself.
Just saying ;-)