Hi Dano,
I am intrigued by your post - '220v AC to 5v DC'
The question in your post seems to bear little relation to the title.
Not knowing what CNC machine is, i tried 'Google', which was
ovewhelming in its wide expanse of information about CNC machines.
Except of course, that it did not give the information required,
namely - what is a CNC machine ... ?
Then i hit upon the simple answer of using Google Images.
Judging from the pictures thus obtained, i now think that they are
the latest type of computer controlled metalworking machines like
lathes, routers, milling machines, grinders, and suchlike.
Most of which run on a three phase supply.
Deciding what the main relay is was not so difficult, i have decided
that this is the relay that feeds the three phase supply to the
machine, and can cut the supply if the system decides to do so.
Here in England these are called 'Contactors'
The operator can usually press a button to engage the contactor to
feed the supply to the machine, very often the machine itself can
disengage the contactor, or the operator can press another button
to stop the electrical feed to the machine.
Now it seems to me that your problem is that the contactor is dis-
engaging, either as soon as its engaged, or shortly afterwards.
Although why this should bring into question the three phase supply
to the machine i cannot quite see.
Unless you are thinking that there may be a brief interuption on one
of the phases, causing the contactor coil to be interrupted and drop
out, leaving the machine dead.
Anyway, whatever the reason, you want to decide if the three phase
supply to the contactor is dropping out,
or if the contactor is disengaging.
Qu:
****
The other day I had a problem that required I know whether the 3 phase
coming in to the machines main relay was dropping out or if the relay
itself was dropping out first.
****
That doesn't sound too difficult.
Using a micro-controller might be a little excessive.
But first, have i got the basic question correct ... ?
And could you explain what you mean by 'first'
Do you mean the contactor is dropping out and then the supply to it
is removed?
Do you mean the contactor is dropping out at apparently the same
time as the supply to it is being removed ?
What is next, after the contactor is first ?
John