Asset Protection - High Voltage Transformers

The new OilQSens^® system effectively controls the proper operating conditions of high voltage transformers, oil-filled circuit breakers, oil-filled cables and oil regeneration plants. Asset protection through effective control saves money, reduces maintenance and prolongs lifetime.

OilQSens^® is a sensor system that measures oil aging via elements of the complex impedance of oils, in particular conductivity and permittivity, together with temperature. Oil aging results from degradation of the oil and products of contamination in the oil. These change the conductivity of insulating oils. Impurities from production or assembly methods, formed acids, aldehydes and peroxides all bind together and form sludge. Sludge attacks the cellulose insulation, inhibits oil flow and prevents heat transfer.

The electrical conductivity of almost all impurities is high compared to the extremely low conductivity of the original pure oil. Sensitive conductivity measurements in the picosiemens range can be used to calculate loss factor tan δ and to identify chemical aging in insulating and lubricant oils during operation. Additionally, permittivity has been found to correlate with moisture in the oil.

The values are temperature dependent but due to the unknown composition of the degraded oil a standard temperature compensation cannot be applied with any accuracy. Instead, a patented, self-learning, adaptive temperature compensation algorithm is used.

Applications for this new technology include all large oil lubricated and oil insulated systems. For instance, turbines including offshore wind turbines, compressor systems, cogen electricity plants as well as high voltage transformers.

OilQSens^®is easy to install and inexpensive to retro-fit. The decentralised, web based monitoring system makes results available anywhere in the world. It can be employed as a stand-alone unit or as part of a more comprehensive condition monitoring system.

cmc Instruments GmbH developed this product in conjunction with local academia and manufacture in Germany.