To obtain complete information about the dielectric properties of transformer oil, the dielectric loss tangent is measured. In the case of new oils, this parameter makes it possible to assess the quality and degree of their purification, and in the case of used oils, the degree of their contamination and aging is estimated. Therefore, devices for measuring the dielectric loss tangent should be available in every laboratory, not only of power distribution companies, but also of companies that produce transformer oils. GlobeCore has developed the TOR-3 device for measuring the dielectric loss tangent and the dielectric constant of insulating oil.
The TOR-3 device is controlled using a computer through specialized software that comes with the device. Measurement and recording of the results are performed automatically. The user only needs to fill the test cell with oil and start the measurement. The device heats the oil to
90°C and performs the measurement. The heating takes most of measuring cycle time. To reduce the duration of measurements in the TOR-3 device, it is equipped with a measuring cell with an internal heating system. Thus, heating and temperature stabilization occur are accelerated. The device quickly reaches the required conditions. One measurement takes 15 minutes. The measurement error of the dielectric loss tangent does not exceed one percent plus 8·10-5, and the measurement error of the dielectric constant does not exceed 2%. High accuracy and stability of measurements is achieved with the new technologies GlobCore implemented in the development of the reference capacitor, as well as preliminary calibration of an empty measuring cell. All cells are interchangeable, so they can be used on one device. For ease of use of the TOR-3 device, the transition to testing the next samples is done without removing the cell. Simply send a command from the computer to open the oil drain valve, let the oil flow into a special tray, and then place a new sample in the cell.
Process of Measuring Transformer Oil’s Tan Delta with the GlobeCore TOR-3 Device
When the unit is off, it can be easily moved around the desktop or carried around the laboratory, due to the compact arrangement of all electronic modules, low weight and convenient handles on the case. None of the dimensions of the TOR-3 unit exceeds forty-five centimeters, and it only weighs 5.5 kilograms. The unit is equipped with a microprocessor, a digital-to-analog converter and a high-voltage amplifier, which allows generating a test signal of the desired shape and operating in a wide range of amplitudes. Therefore, TOR-3 is quite versatile and can be used to measure the dielectric loss tangent according to different test voltage standards. Having a TOR-3 in your laboratory’s inventory allows you to address two problems at once: to determine if new oil is suitable for filling transformers and how long exiting oil can be used without change or regeneration. This increases the reliability of transformer operation and prevents emergencies associated with malfunctions of the insulation system.
More information can be found on our website www.globecore.com
About Authors:
* Jose David Mora Sanchez – GlobeCore
Service engineer
* Oleksandr Pievniev – GlobCore Chief
electronics engineer
* Yevgenii Fedorchenko – GlobCore Chief
design engineer
Please contact us energie@globecore.com
