Case Study – Developing a flexible test tool foundation for Eaton Power Quality Oy

Within the Test Automation Pilot program Softability Group and Eaton Power Quality co-developed a flexible test tool suitable for functional and regression testing of uninterruptible power supplies (UPS). Eaton Power Quality is a part of Eaton Corporation. It is a center of excellence in large UPS system design and production of high power UPS solutions with some 150 employees.

Challenge

Customer objectives: to develop a flexible foundation for a test tool with high extensibility and easy in-house programmability. Furthermore the client’s objective was to closely participate in the development of the test tool to increase the in-house know-how for test automation.

Results

• Executable test tool in Robot Framework and Python capable of executing the challenging multi-phase scenario of Eaton’s patented energy-saving mode (ESS) functionality.
• Set of test libraries providing the test tool with interfaces to UPS under test and the digital measurement and waveform acquisition instruments.
• Close by collaboration transferring the test automation know-how to secure sustainable results.

Story

It is hard to image the modern society without UPSs as companies and individuals demand 24/7 availability of computer services to carry out their business and on-line shopping and video services. A modern UPS is an intelligent software-intensive piece of equipment with software critical in achieving higher power efficiency and orchestrated communication with server virtualization system.

The cost-conscious and environment-conscious clients demand that their UPSs are capable of “eco mode”. Eco mode is a broad term used to describe any UPS mode of operation that improves the efficiency of the system. Typically this means that the UPS system allows utility power to bypass the UPS internal components and directly feed the critical load. If supply power conditions fall outside pre-determined tolerances, the device automatically and immediately transitions back to normal mode. This allows enterprise data centers to receive the ultimate combination of lower operating costs and high reliability.

Eaton’s patented highly efficient eco-mode called ESS (Energy Saving System) was selected as the target for the pilot. Test scenarios where the UPS switches to eco-mode and back to normal mode exercise a lot of UPS functionality and needs a “big” test tool with many interfaces. Testing ESS thus needed a test tool that has powerful features of controlling the UPS, commanding the laboratory supply unit to drop supply voltage, communicating with waveform acquisition instrument to capture the input and output voltage waveforms and analyzing the UPS output waveform characteristics to determine whether the UPS behavior is acceptable or not.

To achieve all that functionality and have a future-proof test tool Robot Framework was selected as the platform with Python as the programming language. Python was the ideal choice for test libraries as Python libraries already exist for communicating with the measurement instruments and with the UPS. Robot Framework on the other hand provided many useful features out-of-box to support ESS testing. For example it was relative straightforward to include graphs of UPS output waveforms to Robot Framework test logs.

For power measurement and waveform acquisition modern measurement instruments were used which provided VISA (Virtual Instrument Software Architecture) compatible communication over TCP/IP. A small Python library capable of analyzing captured waveforms was also implemented. The library further automated the testing by automatically analyzing the waveforms and providing a pass/fail verdict based on the analysis.

A Softability test automation expert and an Eaton R&D test expert collaborated closely during the pilot to ensure the smooth transfer of requirements and know-how between the two parties. The collaboration allowed for experimenting with ideas, pair-programming and hands-on training all to ensure the test tool success.

After completing the implementation a demonstration was organized in the UPS R&D laboratory to show the test tool in full swing. A successful pilot demonstration is nice but the real acid test for success is whether the client is able to carry on and to take the tool to next levels. By the writing of this case study Eaton Power Quality had already made plans and started implementing couple of new interfaces to further automate their testing.

Keywords:

customer services testing