Andy,
if the shield of your cables is any good, there should be no electric
field outside of it (that's the purpose of coaxial shielding), thus, no
interference, so further measures like ferrite rings etc. are useless at
this point.
Your 4 servos draw current from the power supply. The common intrinsic
resistance of this current source will be passed by all of the 4 current
branches, so their votlage drops are superimposed, and this way all the
drives recieve this voltage as a common "noise" signal. The amount of
influence of their function depends on individual properties of the
drive circuits. The only way to reduce this noise influence is reducing
the power supply's intrinsic resistance by blocking the output voltage
with capacitors (electrolytics paralleled with small ceramics) right at
the point where the cables leave the power case. There should be no
piece of a common current path for the 4 drives. Chokes (i.e., coiled
wire with an iron or ferrite core) will increase the resistance and may
only be used in the individual leads to the drives after their
separation from the supply box. They might block high frequency noise at
this point and separate the 4 AC-like which can be favourable.
Peter
Am 08.05.2018 um 13:20 schrieb andy pugh:
I have concluded that I have a problem with noise from my (shared by 4
drives) servo power supply.
The STMBL drive controlling the 4th axis suffers from CRC errors with
the smart-serial control signals and shuts down.
By the simple expedient of running it from a separate PSU this problem
seems to be eliminated.
(It ran fine all night yesterday).
I don't see this as a good long-term solution, so I want to get rid of
the noise in the DC supply. This seems like a job for a choke, but the
cables have a braided shield.
Should the shield pass through the choke, or should I strip the area
where the choke is installed?
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
