PENTA was established in 1937 to manufacture electrical instruments.

In the mid 1940s the company identified a requirement for gas and oil operated (Buchholz) relays to protect oil filled transformers and the first production units were designed and installed at that time. A continual development programme, in conjunction with the Central Electricity Generating Board, led to the production of the Mk10 Buchholz relay with its revolutionary displacement operating principle.

Today PENTA offers a range of Buchholz relays for small and mid-size transformers, many of which are used in substations across the world with an excellent track record of service. Many units remain in service after 50+ years of satisfactory monitoring.

PENTA offer a range of single and double-element type relays as well as a range of Buchholz relays accessories such as dry air pump, oil and gas sampling kits and diode protection units.