AFJ Instruments LT32C/10 Руководство по эксплуатации - Страница 9

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SECTION B: TECHNICAL DESCRIPTION

B.1 • GENERAL

In order to get reliable and comparable test results versus the provisions set forth by the European

and International regulating Authorities, when measuring distortion signals generated by the DUT

and injected into the mains through its power cord, standardized and reproducible test conditions

must be used.

Since the power of the DUT-generated distortion signals, can be compared to the acceptable

standards by measuring the signal amplitude across known impedance, an ARTIFICIAL MAINS

NETWORK CIRCUIT (also called LISN, Line Impedance Stabilization Network) is used.

An ARTIFICIAL MAINS NETWORK CIRCUIT has to provide the SPECIFIED IMPEDANCE OVER THE

WORKING FREQUENCY RANGE (usually, for the case of interest, from 9kHz to 30MHz). Since the

INPUT IMPEDANCE of the MEASURING RECEIVER is 50Ω, the SOURCE IMPEDANCE (output of the

LISN), must also be 50Ω, over the specified Frequency Range.

Moreover, it has to provide sufficient isolation to spurious signals arising from the mains supply

(such signals should be at least 10dB lower than the measurement level, at the measuring receiver),

and also to prevent the mains voltage from being applied to the measuring receiver. The above must

hold for each of the conductors of the mains.

The LISN must also incorporate a switch to enable the connection of the measuring receiver to the

conductor under test, providing the correct termination to the other mains conductors.

When a disturbance output terminal is not connected to the measuring receiver, it shall be

terminated by 50Ω.

The AFJ LISN LT32C/10 has been developed for measurement of line-bound interference's according

to standards. It corresponds to CISPR 16-1-2 directives. The construction uses air coils in the current

path in order to avoid saturation effects with high current strengths. Concerning the construction

the LISN is a V-network because the position of the vectors of the interference voltage.

The AFJ LISN LT32C/10 is used for the measurements in connection with a spectrum analyser or a

measurement receiver. The continuous current load-bearing capacity of 32A is ensured by the use of

large wire cross-sections for the coils. The design of the stabilisation network is continuously low-

impedance for minimum losses.

The compact form of construction, despite the high current-bearing capacity, makes easy use of the

AFJ LISN LT32C/10 for the measurement of high currents directly at the piece of use of the consumer

possible. In this way, measurements of mains-borne interferences can be carried out under

conditions corresponding to practice.

AFJ LT32C/10 LISN - Operating Manual - rev. 3.8 / 2019-01

Distributed by:

Reliant EMC LLC

3311 Lewis Ave, Signal Hill CA 90755,

408-916-5750, www.reliantemc.com