Atec Solar-Electronics-LISN-Stabilization Networks - Manual

LINE IMPEDANCE STABILIZATION NETWORKS
APPLICATION
When measuring conducted radio interference
voltages from active power lines to ground, it is
essential to know the line impedance so that
repeatable tests can be made by more than one
laboratory. Artificial line impedances are specified
in MIL-STD-462, V.D.E., C.I.S.P.R., C22.4, NACSEM
5100, ANSI C63.2 and other EMI specifications.
The characteristic impedance of the five
microhenry and 50 microhenry LISNs brackets
the mean value of power line impedance which
has been measured by independent researchers.
These two inductance values in parallel with
the 50 ohms of the EMI meter fall between the
minimum and maximum line impedance values
which have been measured. The mean value
would be represented by a twenty microhenry
inductor in parallel with100 ohms.
DESCRIPTION
The Solar Electronics LISNs use a series inductor
between the test sample and the power source
to provide the impedance-versus-frequency
characteristic. A coaxial connector with d.c.
isolation is provided for connection to the
associated frequency selective EMI meter. The
power source end of the inductor is bypassed
to ground.
Due to the large current-carrying capability of
some LISNs, it is not always practical to use
a switch for changing inductance values.
Instead, some models are equipped with a high
current pin plug-and-jack combination for quickly
connecting and disconnecting a network and
substituting another. This nylon insulated pin plug
and jack arrangement is a safety feature, well
isolated from inadvertent short circuits, providing
protection to operating personnel.
Current ratings up to 200 amperes are available in
50
ȖH styles and 500 amperes in 5 ȖH styles. See
the chart on the following page.
When measurements are made in a shielded
room, the LISNs intended for F.C.C. applications
will also serve for V.D.E. tests. When operating on
an unfiltered power line, the V.D.E. specifications
require a filter consisting of 250 microhenry
inductor and a capacitor. This filter is included in
the 24 ampere LISN, Type 9348-50-R-24-BNC,
and the 50 ampere LISN, Type 8602-50-TS-50-N.
EMI specifications require one LISN in each
ungrounded power lead. Even though the neutral
is considered “ground,” if it is not connected to
chassis inside the unit under test, the lead must
be tested with an LISN. Therefore, use two LISNs
in d.c. or single phase a.c. applications, three LISNs
for delta-connected three phase circuits, and four
LISNs for ‘Y’ connected three phase circuits.
Explanation of Type Numbers
8602-50-TS-50-N
R.F. connector style
Current rating, amperes
Terminals: TS = Terminal Screw
PJ = Plug and Jack
Series inductance, microhenries
Basic model number
37