Laplace Instruments Products: Conducted

A common 'route' by which noise is transmitted from one product to other 'victim' products is via the mains supply. Therefore a fundamental requirement specified by the EMC regulations is to measure the level of this noise and to ensure that it is within acceptable limits. There are also limits regarding noise conducted down other long cables, such as telecom connections. Conducted emission measurements require a receiver or EMC analyser, together with the appropriate 'transducer' to couple the RF from the EUT (mains) or other cable to the analyser. These 'transducers' are either a LISN (Line Impedance Stablisation Network), voltage probe or CDN.

Details of the relevant items are listed below. 

Use of a Pre-Selector is recommended for any EUT that may produce significant levels of broadband emissions. These are created by impulsive sources such as phase angle controllers, and electronic switching power supplies as is frequently fitted to many modern products.

LISNs provide a stable impedance of 50ohm for RF frequencies up to 30MHz, but require the load current to pass though them. Laplace provides a range of LISNs for single and three phase supplies, up to 100A per phase. The Voltage Probe simply clips on to the line to be measured, so has no current limit, but accuracy is impaired because the impedance is not stabilised.

Both are specified in the EMC standards such as CISPR16, but the LISN is always the preferred choice. The voltage probe is only used when a LISN is not appropriate, for example when the load current is too high to accommodate with a LISN, or when it is not possible to break into the power line to connect the LISN.

If mains conducted emissions are above the limits, one solution is to fit a mains filter. Our FAS system provides a comprehensive filter design tool which provides a quick method to establish an optimum design of filter.

EN55022 now requires measurement of conducted emissions from telecom ports and specifies 4 alternative techniques involving CDNs and/or current probes. 

Finally, EN55015 now specifies a 'CDN method' for the measurement of emissions on power cables for frequencies above 30MHz.

Laplace now has available a full series of suitable CDNs which will satisfy these requirements. 

3GHz EMC emissions Analyser3GHz EMC emissions Analyser
High performance, PC controlled, 3GHz EMC analyser with powerful Windows software application.
1GHz EMC emissions Analyser1GHz EMC emissions Analyser
The SA1002 is a fully featured EMC emissions analyser for all EMC compliance measurements up to 1GHz
Pre-Selectors for EMC testPre-Selectors for EMC test

Pre-Selectors are an essential requirement if measuring conducted emissions that have high broadband noise content. They effectively convert an EMC Analyser into a receiver, as specified by CISPR16.

See Technical Paper for a fully explanation of pre-selectors and why they are important.

LISN & Voltage ProbesLISN & Voltage Probes
These ancillaries enable compliant conducted emission tests. A wide range of LISNs plus voltage probe are available.
Ancillaries.. conductedAncillaries.. conducted

Filters and pre-amplifiers can be vital tools in the armoury when measuring conducted emissions.

The CRS+ is used to check the calibration and operation of conducted EMC emissions test equipment.
Advanced CDNsAdvanced CDNs
A range of CDNs offering flexibility and feedback option, whilst maintaining compliance.
Filter Design System - Mode Analyser - EA-300Filter Design System - Mode Analyser - EA-300

The EA-300 is a core component of the FDS (Filter Design System).

This system is capable of analysing conducted EMC emissions from a product and using its inbuilt software to recommend component values and filter characteristics that would achieve the required reduction in emissions quickly and at minimum cost.

Filter Test Kit  FTK-05Filter Test Kit FTK-05
The FTK-05 is essentially a breadboard facility in which mains filter components can be plugged so that filter characteristics can be quickly assessed.  It is used in conjunction with the FAS system to provide a complete integrated filter design and optimisation solution.