Dielectric fluids

What do we offer for dielectric fluids?

Our group V base oils for use in dielectric fluids are high-performance ester chemistries with excellent sustainability profiles. These fluids can impart performance and stability to dielectric fluid formulations containing PAO and Group III chemistries.

Our heritage in tribology also means we can continue to provide expert advice and speciality additives where friction reduction and anti-wear properties are important. These are increasingly important in electric and hybrid vehicles as the industry moves to low sulphur, lower viscosity formulations, which must have new material compatibility and operate under different conditions.

What are the most important properties of dielectric fluids?

There are several figures of merit that can be used to evaluate the heat transfer capabilities of fluids. One such number is the Mouromtseff number, which allows the heat transfer capability of different fluids to be compared. 

Where notation is defined as: density (ρ), thermal conductivity (𝜆), specific heat capacity (Cp) and viscosity (v). The exponents a, b, d and e can be found from appropriate heat transfer correlations. The fluid with the higher Mouromtseff number has the better heat transfer properties when comparing two fluids.

The exponential factors of the Mouromtseff number are dependent on the flow characteristics. If they are constant, heat transfer can be maximised by increasing density, thermal conductivity, and heat capacity, whilst obtaining the lowest possible viscosity.

What types of fluid can be used as dielectric fluids? 

Traditionally, dielectric oils have been used to cool transformers, capacitors, high voltage cables and switchgear, providing electrical insulation and suppressing unwanted electrical discharge.

There is a great variety in the type of oil that can be used as the insulative fluid, and the chemistry, performance and sustainability of these oily fluids vary greatly. The table below summarises different dielectric fluids and their typical properties. 

Compatible base oils can be formulated into a single fluid, providing property benefits beyond that of a fluid formulated with a single chemistry.

What other attributes of dielectric fluids are important? 

Material compatibility and property degradation upon aging are also important attributes of dielectric fluids.

With the introduction of new polymers, operating conditions, and direct contact with metals in high voltage environments, many new tests are required to validate and approve electric vehicle fluids.

Whilst the industry has no standard test methods defined for these new conditions, you can speak to us about how our industry knowledge and testing programmes can help you define future dielectric fluid specifications. 

Why should you speak to us about dielectric fluids? 

Whether you are a formulator, additive company or original equipment manufacturer (OEM), we  can work with you to develop new and novel synthetic esters to help improve premium dielectric fluid formulations.

We are world-leading experts in the synthesis and manufacture of synthetic esters, having done so for over 70 years on a global scale, collaborating with our customers to create unique speciality chemistry.

Esters offer premium performance and sustainability and can offer best-in-class performance when used in dielectric fluid formulations.