Shaken, not Stirred: Environmental and EMC Testing

What legislation does the inverter need to comply with? Development engineers at SMA face this question with every launch into a new market.

Since these requirements frequently are related to electromagnetic compatibility (EMC), the team at the EMC and environmental laboratory is the first contact partner. Inverters and other SMA products need to meet a great number of requirements:  from functional tests to load tests, from simulations of environmental and grid influences to conditions that take the inverters to the limits of their performance – and sometimes intentionally beyond.

Physics or Voodoo

A Sunny Island inverter in the EMC chamber

The EMC tests ensure that the various devices on the power distribution grid work smoothly with an SMA inverter. What’s more, both the SMA product and transmitter need to function unimpaired, when installed near WLAN, radio or mobile transmitters, for example.

There is a wide range of normative requirements that differentiate between the connection types mentioned above and between locations, such as residential buildings versus industrial area.

This lab has grown substantially and added personnel to support colleagues in the different development departments. Every SMA product can be found in the lab: including Sunny Boy, Sunny Island, Hydro Boy, Windy Boy, Sunny Home Manager, Sunny WebBox from the solar technology division and electric energy converters, control and communications assemblies from the railway technology segment.

For very large systems such as the Sunny Central and components from SMA Railway Technology, the testers leave the confines of Building 4 and use specially prepared testing sites.

They also provide support for an EMC-optimized layout. Their expertise enters at the earliest possible stage of development, so as to avoid long optimization cycles right before a market launch.

By Plane, Train or Truck

Transport simulation with the "shaker"

The term “environmental laboratory” refers to environmental testing aside from EMC. These include mechanical tests and acoustic measurements. Measurements are also taken in the work areas to ensure that colleagues are not exposed to potential health risks through high noise levels, for example, or electrical and magnetic fields on-site.  

Mechanical and Environmental Simulation: 150 Times the Acceleration due to Gravity

The “shaker” is used to simulate conditions that may occur during transport or installation near roads with heavy traffic or train tracks. Designed for devices that weigh up to 160 kg with sizes up to 750 x 750 mm, the shaker’s oscillating table acts on the test subjects with forces up to 150 times the acceleration due to gravity. This quickly gives the developers information about which components begin to resonate under the stress. Packaging also goes through this type of testing.

Free Fall from a Height of 1.20 m

Packaged SMA inverters must be able to survive a fall undamaged. Simulations test falls of up to 120 cm, depending on the individual mass of the unit.

Acoustical Environmental Testing

Acoustical testing on the Sunny Central 800CP

Acoustic tests determine the sound level of an SMA inverter. The anechoic chamber is sound absorbing room and well-suited for measuring systems suchas the SUNNY BOY inverter, as it eliminates sound reverberation.
A different process is used for larger products, such as Sunny Central inverters and systems from SMA Railways Technology. Measurements are taken at various test areas because the anechoic chamber is too small.

Worth Mentioning

This lab is home to two of our colleagues who perform all calibrations at SMA and consult with external partners. SMA uses 6000 measurement tools (e.g., multimeters, spectrum analyzers, burst/surge generators), and the number is growing by the week. Calibrated measuring instruments are essential for valid and standard-compliant test results, whether testing procedures during the development phase or with the series. The inspection equipment monitoring department either calibrates or monitors almost all measuring instruments at SMA.

Strict Certification Tests

The EMC lab has very high quality standards, as shown in the certifications from UL, Intertek and DAkkS (according to IEC/ISO 17025), and the colleagues there have reasons to be proud. This allows them to conduct certification testing in the lab. They must consistently track their test samples during testing as well as document the testing and documentation processes. These processes are also subject to annual review. These measures all combine to ensure that test results are reproducible between different testing labs.

To meet the strict standards and guidelines required by globally recognized test certificates such as the CE mark for Europe or the UL mark for North America, SMA closely cooperates with certification companies worldwide.
As a consequence, SMA was the first company to receive a UL certificate for transformerless inverters.

There is no doubt that, with all the new technical challenges facing inverters and growth into new markets, the colleagues in the EMC and environmental laboratory will continue to have many interesting tasks awaiting them.

They have compiled more detailed information about EMC at here.