Saelig Introduces Economical Line Impedance Stabilization Network For Pre-Compliance Testing

Saelig Company, Inc. announces the availability of the TBLC08 Line Impedance Stabilization Network (LISN) which enables measurements of line-conducted interference within the range of 9kHz to 30MHz, according to the CISPR16 or other standards, before any formal testing commences. The TBLC08 is designed especially for pre-compliance testing of single phase, AC-powered equipment with supply voltages up to maximum 260V. Noise transmitted on the line and neutral conductors coming from equipment under test can now easily be measured. The TBLC08 is also equipped with a switchable limiter/attenuator and an artificial hand connection for simulating handheld equipment.

Formal compliance measurements of AC line-powered products requires an expensive set-up consisting of an anechoic or screened chamber, a measurement receiver that complies with the requirements of CISPR 16 or other standards, a 50uH LISN, and a suitable table for the equipment being tested. This all takes great effort and cost in order to obtain optimum accuracy and repeatability. However, pre-compliance measurements can be done before formal testing during the product design phase, to give an approximation of the EMC performance of the Device Under Test (DUT) at a fraction of the cost of full compliance testing. This gives great confidence of success when it comes time for the expensive testing to be done. Now useful measurements can be made with an affordable spectrum analyzer that has suitable sensitivity, bandwidth and detectors. The recent advent of lower cost spectrum analyzers has made EMC pre-compliance testing affordable – and essential - for any company which develops electronic products, and offers an excellent return on investment.

An LISN is basically a filter inserted between the supply input terminals of the DUT and the supply which is used to power it. It presents a defined impedance for the noise which is produced by the DUT and emitted via the supply cables of the DUT. The impedance seen by the conducted RF emissions is 50ohms in parallel with 50uH. Having a defined impedance for the emissions at the DUT terminals eliminates any influence of the power source impedance.

The TBLC08 LISN’s RF output section is AC coupled to either line or neutral, selected by a rotary switch on the front panel. This RF section also contains an attenuator/limiter and a high pass filter to attenuate harmonics originating from the mains supply. The attenuator/limiter protects the measurement receiver / spectrum analyzer input from high amplitude pulse transients. When performing conducted noise measurements with handheld devices such as power tools, hair driers, or kitchen tools, the Artificial Hand Network mimics the influence of a human hand.

Manufactured by Singapore-based Tekbox Digital Solutions, the TBLC08 Line Impedance Stabilization Network is available now from their authorized North American distributor Saelig Company, Inc. Fairport, NY.