Design of a Three Phase Portable Reference Standard

Three Phase Reference Standard (TPRS) is a device used to measure the load and test the accuracy of three phase energy meters at residential as well as commercial installations. The device is used primarily by State Electricity Boards and electrical laboratories.

Being a low volume product, the TPRS is manufactured by only a handful of manufacturers across the globe, only one of them being Indian. The Indian model is relatively less expensive but leaves much to be desired in terms of functionality and styling. Emantras Product Design was approached by Signals & Systems India Private Limited (SANDS) to design and develop a new model of TPRS for the Indian as well as international markets. SANDS is a ISO 9001:2000 certified company specializing in DSP and embedded solutions for the power sector.

The product being highly technical, we were completely at sea when SANDS engineers showed us the bare circuit assembled on a table! The first step for us was to understand all the parts, accessories and their inter-relationships.

Our team observed SANDS engineers performing all possible operations on the TPRS, namely Calibration, Error Checking and Data Transfer. We prepared a flowchart of the steps involved in each of these operations. Based on our observations and discussions with the SANDS team, we optimized the Usability Cycles of the product for efficiency and fool-proof performance.

The next step was to work out a physical embodiment for the product. All the loose parts and accessories were measured accurately in order to have a dimensional database of our building blocks. We generated five different arrangements for encasing the main console and all the accessories.

For each of the arrangements, we tried numerous configurations and compared them in terms of volumetric efficiency, usability and number of casings required. One of the options in arrangement 5 was selected for development.

For the outer carry case (housing the hand-held unit and accessories), our client preferred to go for ready-made instrument casings due to the low volume of the product. We surveyed the internet for ready-made casing models suiting our dimensional requirements. The selection was made based on volumetric efficiency, material & construction, self-weight, available colours, appearance and of course, price!

The dimensions of the hand-held unit were frozen and styling possibilities explored for the same.

The selected design was modeled and detailed out in ProE.

Special attention was paid to the design of the keypad, with due consideration to ergonomics, logical clustering and relative frequency of usage.

3D rendered images were generated for the design so as to convey a realistic picture to the SANDS management, and in turn, to their customers.

A rapid prototype of the hand-held casing was generated through the FDM process. The internal components were assembled and the unit was tested for ergonomics and electrical performance. After some minor dimensional adjustments, the design was approved for production.

Being accustomed to designing consumer products, this project (an industrial product) was a welcome break for us. We realized that however technical or complicated a product may be, design has the power to significantly enhance its usability and of course, its aesthetics.

Shoubhik Dutta Roy