SU1557460A1 - Apparatus for measuring temperature of windings of a.c. electric generators under load - Google Patents

Abstract

The invention relates to electrical measurements, namely to control the temperature of the windings of AC electric machines under load. The purpose of the invention is to increase the sensitivity and speed. The device contains an electric machine 1 and an alternator 2, the first and third phases of which are connected via separation capacitors 3 and 4, and the second phases are connected directly. The first and second phases of the electric machine are connected in series with the third capacitor 5 and the primary winding of the first compensation transformer 6. Its secondary winding is connected in series with the choke 7 and the capacitor 8 constituting the first filter 9 and connected to the first and second phases of the electric machine. The output of the first filter 9 (capacitor leads 8) is connected to a constant current source 10. The primary winding of the second compensation transformer 11 through the fourth capacitor 12 and its secondary winding through a choke 13 and a capacitor 14 constituting the second filter 15 are connected in parallel to the separation capacitor 3. A voltmeter 16 is connected to the output of the second filter 15 (capacitor 14 leads) this voltage. The constant current of source 10 causes a voltage drop across the coil of the second phase of the electric machine and is present as a potential difference on the plates of the separation capacitor 3. A voltmeter 16 detects the constant component of the capacitor 3 proportional to the temperature of the windings of the electric machine. The constant voltage source 17 compensates for the initial resistance of the monitored winding. 1 il.

Description

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The invention relates to electrical equipment and can be used to protect an electrical apparatus or its 2Q from damage due to temperature extremes, as well as to control the temperature of the winding of an electrical apparatus during the design development, technological process and state tests.

The purpose of the invention is to increase the sensitivity and speed.

The drawing shows the structure of the device.

The device contains an electric machine 1 and an alternator 2, the third and first phases of which are connected respectively via separation capacitors 3 and 4, and the second phases are connected directly, in series connected the third capacitor 5 and the primary coil I of the first compensation transformer 6, whose secondary winding II, connected in series with the choke 7 and the capacitor 89 by the components of the first filter 9, is connected to the first and second phases of the electric machine under test. The output of the first filter 9 (capacitor leads 8) is connected to a constant current source 10. The primary I and secondary II windings of the second compensation transformer 11 through the fourth capacitor 12 respectively and the choke 13 connected in series and the capacitor 14 constituting the filter 15 are connected in parallel to the separation capacitor 3 ". To the output of the second filter 15 (capacitor terminals 14. ) A voltmeter 16 is connected via a constant voltage source 17.

five

The device works as follows.

Electric machine 1 is powered by alternator 2 through separation capacitors 3 and 4 and the second phase directly. At the same time, the first and second phases of the electric machine 1 from source 10 through the first filter 9, consisting of a capacitor 8 and droplets 7, and the secondary winding II of the first compensation transformer 6, flow a constant measuring current.

The primary winding I of the first compensation transformer 6 is connected via an isolating capacitor 5 to the first and second windings of the test machine, and windings I and II are turned on in antiphase. In this case, winding II protects the source 10 of the direct current from the variable component. The uncompensated difference is filtered by the block 9. Connecting the compensation transformer through the initial coupling capacitor 5 reduces the noise at the source 10. The voltage from the coupling capacitor 3 is fed to the secondary winding II of the second compensating transformer 11 and through the choke 13 and the capacitor 14 constituting the second filter 15 is supplied to the voltmeter 16. The primary winding I of the compensating transformer 11 is connected in parallel to the coupling capacitor 3 via the fourth capacitor 12. The windings I and II are connected in antiphase, so that the winding II compensates for the variable component of the voltage on the capacitor 3. The uncompensated difference is filtered by the unit 15.

one

The constant voltage from the output of the filament 15 through the source of the direct current source 17 is fed to the recording device 16 - a direct current voltmeter. Thus, when a measured current flows on the second winding of the electric machine 1 being tested, the regulator is stabilized, we create a voltage drop on the winding in a cold state

and, (k + ty). 10th (B)

where k is a material constant, for copper, for aluminum

td is the cold winding temperature,

on the source 17 of a constant voltage, the voltage is adjusted (B), then later on the registering 16 device we will directly read the measured value — the winding temperature, since all the voltage from the measured winding through the second and third phases The alternator 2 and the third phase of the electric machine 1 are fed to the first coupling capacitor 3 (the leakage resistance of the coupling capacitor 3 is greater than the resistance of the rest of the circuit). Capacitors 3 and 4 are electrolytic and constitute farad fractions that are included in pairs and opposite. At the same time, it was obtained in relatively small dimensions. non-polar large capacitor. Due to the fact that capacitor 3 is of large capacity (the share of farada headlights is yes), even from a significant current of an electric machine the fall of the variable component on it is less than 3 B.

In the proposed device, a reduction in the level of interference (signal-to-interference ratio) of 100 or more is achieved, which makes it possible to reduce the measuring DC current in the tested phase of the electric machine. This increases the sensitivity, because it reduces the effect of the magnetization of the tested machine, and increases the speed, because reducing the requirements for filter elements leads to a decrease in the constant time. In practice, the sensitivity is increased 10 times, while the slope 5574606

- It is possible to test electrical machines with winding resistance, 10 times less than the limit for a known device, the test DC current is also reduced by 10 times, and the section on the improvement of the signal-to-interference ratio is used to reduce the time constant.

U filter, which allows to increase the speed by 3 times.

Claims (1)

Invention Formula A device for measuring the temperature of the windings of AC electric machines under load, comprising a first compensation transformer, the first output of the primary winding of which is connected to the first phase of the electric machine, the second phase of which is connected to the first output of the secondary winding of the first compensation transformer, the second output of which is connected to the first phase of the electric machine through the first filter, consisting of series-connected throttles and a capacitor, in parallel with which a source is connected current, the second compensation transformer, the first output of the secondary winding of which is connected to the third phase of the electric machine, and the second output is connected to the second filter consisting of serially connected droplets and a capacitor, in parallel with which are connected connected in series a constant voltage source and a voltmeter , and a capacitor, the first and third phases of the electric machine and the alternator are connected via coupling capacitors, characterized in that, in order to increase capacity and speed, a second capacitor is inserted, the second terminals of the primary windings of the first and second compensation transformers are connected to the second and third phases of the electric machine respectively via the third and fourth capacitors, the first terminal of the primary winding and the second compensation transformer and the second filter are connected to the third phase alternator, and the second phase of the electric machine and the generator are connected directly.