Temperature measuring systems for transformers

Thermometer with bellow-type or Bourdon technology

Continually monitoring temperature is one of the most important tasks for ensuring the functionality, reliability, and operational readiness of a transformer. Two generic thermometer technologies – the Bourdon and the expansion bellows principle – have developed over the decades and are widely used today. MESSKO customers can obtain both these proven technologies from one source. The MESSKO BeTech thermometer range relies on proven bellow-type technology, while the MESSKO COMPACT and TRASY2 series are based on the well established Bourdon principle.

Principles of function Bourdon and Bellow-type

Bellow-type technology

The measuring system of the oil and winding thermometer with expansion bellows consists of four basic components: the temperature sensor, the capillary tube, the expansion bellows for displaying the measurement and, finally, the expansion bellows for compensating for the ambient temperature. As with the Bourdon technology, this measuring system is also filled with a liquid. However it is depressurized. With bellow-type technology, heating up the sensor – transferred by the capillary tube - causes the liquid to expand and thus a corresponding linear movement in the first expansion bellows (display). This movement is transferred mechanically with relatively high force to micro-switches and is ultimately displayed. With this technology the first expansion bellows ensure a high force for the display and for actuating the micro-switches; the second expansion bellows provide the best possible compensation for the ambient temperature. Furthermore, the expansion bellows system is robust, durable, and maintenance-free.

 

Bourdon technology

The measuring system of the oil and winding thermometers with Bourdon springs consists mainly of three functional units: the temperature sensor, the capillary tube and, finally, the Bourdon spring - including the actual pointer - are the most important components. The completed measuring system is filled with a liquid and is pressurized. When the temperature sensor is heated up, the liquid in the measuring system expands and the pressure rises. This rise in pressure is then transferred accordingly to the Bourdon spring via the capillary tube. The coil-shaped spring now converts the rise in pressure into a rotating movement, corresponding to the rise in temperature. It indicates the change in temperature directly via the pointer located at the center of the coil – and voilà! With Bourdon technology, the robust and heat-treated (memory effect) Bourdon spring and the direct transfer of the rise in pressure to the pointer ensure an extremely precise and permanently stable temperature display. The system requires no maintenance and retains its mechanical characteristics throughout its entire service life.

 

No matter whether you are looking for a solution for oil or winding temperature, bellow-type or Bourdon technology, our product range can help:

The MESSKO BeTech oil and winding thermometer with bellow-type technology comprises four main components: the temperature sensor, the capillary tube, the first expansion bellows for displaying the measurement and actuating the micro-switch, and the second expansion bellows for compensating for the ambient temperature. As with the Bourdon technology, the measuring system is filled with a liquid but is depressurized. With bellow-type technology, the intelligent interaction of the functional units ensures that the micro-switches are switched correctly.

The MESSKO COMPACT type series consists of two types of temperature measuring instruments which are compact and contain everything you need for the temperature measurement, display of the measured values, alarm messages, and remote indication of the measured values. No additional equipment is needed! An extra advantage is that the temperature sensors are quite small and fit in all standard transformer thermometer pockets and shafts.

The MESSKO TRASY2 thermometer range has been designed specially for measuring temperatures in distribution and power transformers. The TRASY2 series is a stand-alone, energy-independent indicator thermometer which uses micro-switches for various switching functions. The measured value is captured by a liquid-filled temperature sensor and is then transmitted via a spiral spring which is linked to an indicator axle. The thermometer has micro-switches with fully adjustable settings.