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INSTRUCTION MANUAL
LI-3P-2x Series
3-PHASE LINE IMPEDANCE STABILIZATION NETWORKS (LISNs)
SECTI ON 4 -
PRODUCT APPLICATION
1912 1 E l T o ro R d
●
Si l vera do, Ca lifo rni a 9 26 76
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(9 49) 459 -96 00
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co m-p o wer. com
REV031418
4.0 LISN Installation
4.1 LISN
Theory
The LI-3P-2x Series Line Impedance Stabilization Networks are specifically
designed to provide the necessary measurement platform for power line
conducted emissions (disturbance measurements) compliance testing as
required for FCC regulations, CISPR/EN/ETSI and other worldwide standards for
commercial products. The LISNs are fully compliant with the requirements of both
CISPR 16-1-2 and ANSI C63.4.
Line Impedance Stabilization Networks provide standardized line impedance to
the EUT during conducted emissions testing which is independent of the external
power line impedance. The standardized impedance enables consistent
readings for RF noise measurements on the power line.
In addition to providing a standardized impedance, the LISN also acts as a low
pass filter for the power to equipment under test. The LISN provides isolation
between the power source or mains network in order to reduce the amplitude of
unwanted ambient signals/noise while allowing the power to pass with minimal
voltage drop. This filter is comprised of a single stage low pass LC filter. The
inductor (L) used in all Com-Power LISNs are air core type to eliminate the
possibility of saturation and to provide stability.
The LISN also provides a low impedance, capacitively coupled, minimal loss path
for the RF noise from each EUT power conductor to the measurement port. The
loss incurred along each of these paths is referred to as Insertion Loss. Insertion
Loss factors are individually measured and provided for each line in the network.
These factors must be considered in order to achieve the highest measurement
accuracy. The insertion loss factors (in dB) are added to the measured values (in
dB
μ
V). A basic example schematic of the LISN is illustrated in Figure 4 below.
FIGURE 4 -
Example Schematic of LI-3P-2x Series LISN
Measurement
Port
L1
L2
L3
N
L1
L2
L3
N
PE
PE
50 μH
50 μH
50 μH
50 μH
250 μH
250 μH
250 μH
250 μH
1 kΩ
1 kΩ
1 kΩ
1 kΩ
50Ω
50Ω
50Ω
220
nF
220
nF
220
nF
220
nF
