On Tue, 6 Aug 2024, Viesturs L?cis wrote:
Date: Tue, 6 Aug 2024 23:44:21 +0300
From: "[UTF-8] Viesturs L?cis" <viesturs.la...@gmail.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: [Emc-users] Question to electrics gurus: Correct setup for rectifier
+ capacitor
Hello!
Recently I have posted some questions about the retrofit that I am
working on and now I have encountered an issue that I cannot figure
out.
The thing is that I am swapping original Yaskawa servo drives with
Mesa 8i20. One of the things for that was 3phase rectifier bridge (it
takes 230 VAC input and provides 340V output) and 4700 uF capacitor
for smoothing the ripple.
It took me some time and some patience from PCW to fix the config and
in the end I got one 8i20 to move one joint in the machine. So my next
step was adding 2 more 8i20 drives for remaining 2 joints. It ended up
with a blast in one 8i20. So I replaced it as well as I had to replace
rectifier bridge. But now my issue is that protection fuse is tripped
as soon as I enable machine power.
1) only rectifier bridge connected - all good
2) rectifier bridge + capacitor - fuse tripped immediately
Note that I have not yet connected DC bus to 8i20 drives.
I checked capacitor with multimeter, it was showing 180V DC (and it
did not decrease in that time that I was holding multemeters pins
there). I am not sure if that is some residual charge from previous
(which I doubt) or if that was some charge that was acquired before
fuse was tripped, but this seems to me like a good capacitor. Is that
correct?
I do not understand why was everything fine in initial testing - I did
turn machine on and off lots of times and capacitor was discharged
(and recharged!!!) numerous times. I have swapped that fuse for
identical unit from a machine that has yet to go through the retrofit
process. And it is the same.
So my question to electronics gurus - could capacitor be damaged or
was it just a beginners luck that everything worked and do I need to
introduce some inductor between rectifier bridge and capacitor to
limit the startup current that charges capacitor?
Viesturs
Typically a NTC is used to limit the surge current, either in the AC line
or the DC between the bridge and the filter capacitor. Here is a NTC
manufacturers page on this usage:
https://product.tdk.com/en/techlibrary/applicationnote/howto_ntc-limiter.html
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
Peter Wallace
Mesa Electronics
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
