Schwarzbeck NNLK 8129 Line Impedance Stabilisation Network

Schwarzbeck A V-LISN from the series of the NNLK line is required to measure conducted interference voltages according to VDE-, CISPR- and related standards. It provides the device under test with a mains connection that has a standardized impedance of 50 Ohms || 50 µH and reduces interference voltages coming from mains. The interference voltage of the device under test is decoupled via a 7 kHz high pass filter to the EMI measurement receiver. A path selector switch allows measuring both paths, one after another. The paths that are not being measured are internally terminated with 50 Ohm load.

For measurements conforming to standards the references in the standard CISPR 16-2-1 have to be followed. Amongst others it is described that the AMN has to be grounded with a short and wide ground strap to the wall of the shielded chamber (or provisionally to a sheet metal board at the wall).

The LISN can be grounded using the screw terminal at the front panel as well as the aluminum brackets at the rear side.

According to CISPR 16-2-1 the connecting cable of the device under test has to be laid in a 40 cm distance to the metal wall and the length of the cable should be 80 cm or being laid meander like. The way the cable is laid but also the capacitance of the equipment under test can influence the disturbance voltage especially at higher frequencies.

Instructions for use:

The purpose of a LISN is to provide the device under test with energy and to decouple it from mains, to carry the interference voltage to the EMI measurement receiver and to load the RF emitted by the device under test with standardized impedance.

Hazard warnings

The LISN may only be used by qualified personnel! The device under test may only be connected to or disconnected from the LISN when no voltage is applied to the LISN at all. There is a risk of fatal injury from electrical current!

Important! Connect the LISN to protecting earth BEFORE applying any voltage to it! For this purpose you can use the screw terminal at the front panel and the aluminum brackets at the rear side of the device.

Due to high capacities very high leakage currents can occur (~1 A). Thus it is not possible to use a residual current operated circuit breaker. It is recommended to use an isolating transformer.

The supply voltage has to be applied at the back panel of the LISN by using the wing terminals.

Important! The operator has to make sure that the maximum current is limited to 200 A at the supply side. There is no fuse built into this LISN to protect the device under test!

The device under test has to be connected to the wing terminals at the front panel.

The coaxial RF output has to be connected to the EMI measurement receiver using a BNC coaxial cable. You can choose the path that needs to be measured with the path selection switch. The paths that are actually not measured will be terminated with 50 Ohm automatically.

Artificial mains networks from the NNLK line do not have the pre-filter choke contrary to the NNLK line (exception: NNLK 8121). This is due to the high current rating and complies with the CISPR standard for LISN’s for band B. They basically work in band A also but are specified starting from 150 kHz.

Maximum voltage In basic configuration a maximum voltage of 250 V, 50/60 Hz or 400 VDC can be applied between a path and ground. Between two paths a voltage of 400 V, 50/60 Hz may be applied.	The option "400/700 V" raises the maximum possible voltage than may be applied between a path and ground to 400 V, 50/60 Hz or 630 VDC. Between two paths 700 V/ 50/60 Hz may be applied with that option.