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SeCtION 13 |
- As explained above, it may trip a gfCI feeding multiple AC outlet circuits / recepta-
cles. In such cases, disconnect devices connected to the other AC.
- outlet circuits / receptacles served by this gfCI.
6. following additional guidelines may be followed to reduce the effects of Rf Noise:
A. use additional appropriate AC radio frequency interference (RfI) power line
filter immediately before the AC input of the power supply. for example,
250VAC, 20A filter "f1700dd20" from curtis industries (www.curtisind.com)
or similar. filtered, ferrite coated cord set (www.emceupen.com ) is another
choice. These cord sets, with integral line interference filters, reduce common
and differential mode interferences over a wide frequency range. Because
they are shielded, they are also effective against radiated interferences. In
addition to the built-in filter networks, the cable conductors are coated with
an Rf absorbing ferrite compound. This provides additional attenuation at
high frequencies that is lacking in most regular lc filters. The Rf absorption of
the ferrite-coated cable avoids resonance's at high frequencies, reducing the
conducted and radiated Rf noises even further.
B. use additional appropriate DC radio frequency interference (RfI) power
line filter immediately after the DC output of the power supply. for example,
80VDC, 100A filter from "DC" series by corcom (www.corcom.com) or 80VDC,
100A filter from "fD" series by curtis industries (www.curtisind.com) or
similar.
C. Twist the Positive and Negative wires from the output of the power supply to
the radio.
D. The DC side Positive and Negative outputs of these power supplies are iso-
lated from the chassis. As explained at paragraph 5 above, the noise currents
are filtered to the chassis ground and the chassis ground is connected to the
earth ground through the earth ground pin of the AC power outlet recepta-
cle. Avoid connecting (referencing) the DC Negative output terminal of the
power supply to the earth ground.
E. Connect a 1/4" wave length of wire on the Negative terminal of the power
supply. Connect one end of the wire to the Negative terminal and leave the
other end free. The wave length corresponds to the wave length of the inter-
fering frequency. (May not be practical for long wave lengths).
[ Formula: Wave length (meters) = 300 / Frequency in mhz ]
limiting electromagnetic
Interference (eMI)
SAMLEX AMERICA INC. | 19
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