SU469898A1 - Device for controlling the temperature of high-voltage power transformers - Google Patents

Description

one

The device belongs to the measuring technique and can be used to measure and control local temperatures on the windings of high-voltage transformers.

A device for remote temperature control is known, which is a temperature sensor — and a receiving transmitter. The temperature sensor includes a piezoceramic ultrasound emitter, a heat indicator. And a generator resonator. However, a significant environmental effect is observed, with the result that the measurement accuracy is sharply reduced; large dimensions of the sensor; The large dimensions of the filament source and its insertion aa work the entire device.

The purpose of the invention is to improve the measurement accuracy, reduce the size of the device and create full power autonomy. For this purpose, the thermal indicator, the resonator of the generator, and the ultrasound emitter are combined in one node, which is an autogenerator in a three-electrode piezocrystal, which is shaped like an ultrasound emitter.

The drawing shows the cx-ma device.

The sensor is mounted on a transistor I, the frequency of the generated oscillations is determined by the parameters of a special three-electrode piezocrystal 2. The working point of transistor 1 is determined by the resistance value of resistors 3 and 4. The sensor power supply circuit is made on a single-winding transformer 5, diode 6 and a semiconductor zener diode

7. The entire sensor is mounted on the board strictly in the same plane and when installed, the winding bus of the power transformer is oriented in space along the scattering fields so that the axis of the core of the transformer 5 is located along the scattering power lines. The magnetic flux generated by the windings of the power transformer induces in the winding of the transformer 5 EMF sufficient to power the measuring circuit. The voltage taken from the winding of the transformer 5, rectified by the half-wave circuit with diode 6, is stabilized by a Zener diode Zener diode 7, and is fed to the measuring circuit of the sensor.

The device works as follows.

The measuring circuit of the sensor is an auto-oscillator. The signal is removed from the metallized electrode of the piezocrystal.

positive feedback to ensure stable operation of the generator. The frequency of the oscillations generated is determined by the resonance frequency of the non-crystal. Since the parameters of the material from which made

a piezocrystal (titanium barium), depending on its

temperature, then the resonant frequency of the crystal and, therefore, the frequency of the generated oscillations depend on the temperature of the piezocrystal 2. Thus, the piezocrystal performs the functions of a measuring organ and is incident directly on the surface, the temperature of which is measured. During operation, the piezocrystal radiates ultrasonic vibrations into the surrounding elastic medium (transformer oil), the frequency of which is proportional to the temperature of the radiator.

On the inside of the transformer tank, an ultrasonic oscillation receiver is installed, connected to the input of a multi-range electronic frequency meter, the scale of which is calibrated directly in ° C.

Subject invention

A device for controlling the temperature of high-voltage power transformers containing a thermal indicator, a generator resonator, a piezo-ceramic ultrasound emitter and a power source, characterized in that, in order to reduce dimensions, improve measurement accuracy and create complete power supply autonomy, the thermal indicator, the generator resonator and the ultrasound emitter are combined in one node, which is an oscillator on a three-electrode piezocrystal, which is shaped as an ultrasound emitter, and as a source A single winding transformer with an open magnetic circuit is used.