The company was founded in in Switzerland by Emil Haefely, an inventor who played a decisive role in the development of the electrotechnical industry at beginning of the th century. With the patent of the OIP Condenser type bushing in by Emil Haefely, the company became a pioneer in Oil type bushings. Trench France is part of the Trench & HSP Bushing group belonging to Siemens with locations in France (Trench France), Germany (HSP) and China (THVS). This close cooperation for innovation and design is supported by Siemens process and manufacturing know how. In , the Trench Group decided for Trench France to focus specifically on bushings by making extensive manufacturing investments and improving all customer relevant processes.

Siemens Limited, launched manufacturing of High Voltage Instrument transformers in , in the existing HV products factory at Aurangabad in India. The state-of-the-art facility is producing CVTs with Oil insulation and CT/PTs with SF insulation and is the only factory in India manufacturing SF CT/PTs with Composite insulators with technology support by Trench Germany. The factory also supplies GIS components (Instrument Transformers and Bushings) and Grading Caps to Siemens India. With a total area of Sq. Meters, Siemens Instrument Transformers is the market leader for CVTs in the domestic market. For SF CT/VTs, the facility has its own set up of Composite insulators. There are some key utilities/ industries from Power Generation in India, who have completely switched their CT/PT requirements to SF technology. Siemens India is also working continuously together with Global R&D on new generation and digitalized products to serve the customers with advancements further.

For more than years, Trench has supplied air core reactors to the electric power industry. Founded by Tony Trench in , Trench Canada has demonstrated versatility, confirmed capability and compliance with the most stringent quality standards to ensure that Trench maintains a worldwide leader for coil products. Located in Scarborough, Ontario, Trench has proven the effectiveness of vertically integrated operations in the manufacturing of air core reactors. Significant investments in the factory layout and process optimization over recent years makes Trench Canada a reliable partner for customers.

Trench Italy is located in the village of Cairo Montenotte, in the northwest of Italy near the town of Savona and approximately km from Genoa harbor. The Company was founded in under the name of Scarpa e Magnano. In came the merger with Magrini and the whole enterprise was acquired by Merlin Gerin in , before being integrated in the VATECH group in and finally in the Trench Group in . Since the production start of oil insulated instrument transformers as early as , Trench Italy has a high competence in the design and manufacturing of high voltage instrument transformers. The European production of oil insulated voltage and current transformers, capacitor voltage transformers, grading capacitors and special instrument transformers of the Trench Group is concentrated in Cairo Montenotte on a . m² total surface. Significant investments in production and testing facilties since as well as the outstanding technical expertise allowed Trench Italy to introduce state-of the art manufacturing processes that are leading to high quality products and a proven reliability.