Quote:
Originally Posted by Paul Haese
Thanks for the detailed response Gary.
I did not get any chokes or filters.
I have read the manual as you pointed out the sections and I find it odd that Chokes have not been supplied. I will keep the shielded cable. Do I install the shield at the earth point? The extended metal plates are heat sinks. I have earths on these as shown on the drawings.
I will place the shielded cable well away from the mains delivery cables.
Any suggestions as to chokes. The shielded cable needs to be wrapped twice through a ferrite core. What am I looking for here?
I take it the filters are like those you suggested earlier?
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Hi Paul,
I suspected they hadn't supplied you with the line filter or choke.
On page 11 of 127 in the inverter manual, the lower drawing shows the cover removed
and they indicate a ground terminal. It is hard for me to tell from the line art if
that terminal is on the actual metal chassis of the inverter, but if it is, that is
where you want to connect the shield of the cable that goes from the inverter to
the motor. Use the shortest, fattest piece of cable you can find that allows
for attachment on the terminal and shield. Alternatively, if the cable is longer than you need,
peel back the shield, connect that to the ground terminal and cut short the wires
so that they remain shielded along their entire length.
If you had the inverter installed inside another metal cabinet or enclosure,
what they are suggesting is that the cable shield would terminate at a gland
on the enclosure at the point where the cables pass through into it.
Try and keep the entire cable as short as practical.
For that extended metal plate that you have identified as a heat sink, when you say
"I have earths on these as shown on the drawings", good, but could you please explain
to me exactly what you did there?
The ferrite toroid cores come in a range of dimensions. Here is a drawing of
one -
http://www.farnell.com/datasheets/1696282.pdf
This happens to be this one -
http://au.element14.com/wurth-elektr...8?Ntt=74270097
I happen to have purchased a couple of these myself in the last two weeks to use for measuring tiny currents.
However, if you search on the Element 14 web site, you should have no problem finding one
with an inner diameter that you think you will get the cable to loop through
a couple of times.
When you wrap the cable through the ferrite twice, if possible, try and keep
the two windings physically spaced apart. This helps reduce interwinding
capacitance, which is a good thing.
The manufacturer suggests placing the ferrite core as close to the inverter as possible.
The ferrite itself is a poor conductor but it has a high magnetic permeability.
What the ferrite does is it will choke common-mode currents passing through
the cable. The ferrite core can saturate so it has an upper limit to how effective
it is, but it will knock several dB of noise off.
Notice that the filter they recommend is on the power line side of the inverter.
They are trying to block noise being conducted back through the mains and into
your other gear.
Best Regards
Gary