TET ESTEL | 1,175 followers on LinkedIn. Design, Production, Testing, Innovation, Promotion of electric power equipment TET ESTEL is a company with a history dating back more than 155 years, a comprehensive track record of completing challenging and innovative projects serving multiple industries, and capable of providing solutions within short lead-times at the best-in-class price-to-quality ratio. Product quality and customer-oriented approach are cornerstones of our production philosophy.