SU491843A1 - Device for measuring the temperature of the winding of electrical machines - Google Patents

Description

one

The invention relates to electrical methods for measuring peelectric values, more precisely temperature.

Devices are known for measuring the temperature of a winding of electrical machines, comprising a thermal sensor, which uses the winding of an electrical machine, AC and DC transformers, and a rectifying device.

However, these devices are not suitable for measuring the temperature of the windings directly under the AC load.

To measure the temperature of the windings under alternating current load, in the proposed device, the primary windings of the alternating current transformer and the direct current transformer are connected in series with the temperature sensor, and parallel to the thermal sensor and primary windings of transformers connected between themselves afterwards, the filter is switched on through the filter current.

The DC transformer is made with a correction winding, which is connected to the AC transformer secondary winding, and the DC transformer secondary windings, connected in pairs, in series and opposite, are connected via a rectifying device to the measuring device.

The AC transformer is made of a three-winding, one of the secondary windings is connected to the correction winding of the DC transformer, and the other, demagnetizing winding, is connected to the DC source circuit.

The drawing shows the scheme of the described device.

The terminals of the phase windings 1, 2, 3 of the electric machine are connected to an alternating voltage network, and the phase winding 3 used as a thermal sensor is connected to the network through the primary current transformer 4 of the alternating current connected in series and the primary winding of the alternating current transformer 5.

The DC transformer 5 is made with a correction winding 6, which is connected to the terminals 7 of the secondary winding of the transformer 4, and the secondary windings of the transformer 5 connected in pairs, in series and oppositely, through the rectifying device 8 are connected to the measuring voltage network . The direct current source 10 is connected to the primary winding of the transformer 5 from the supply line through the positive busbar, and the negative busbar through the demagnetizing winding 12 of the transformer 4 is connected to the connection point of the phase windings 1, 2, 3. Source 10 and demagnetizing winding 12 transformer 4 is shunted with a capacity of 13.

The device works as follows. Source 10 supplies a direct current of no more than (1)% of the operating current of the phase winding 3 but the following chain: inductance 11, primary winding of transformer 5, primary winding of transformer 4, phase winding 3, demagnetizing winding 12 of transformer 4. Therefore, the primary windings of the transformer 4 and the transformer 5 and the phase winding 3 a current flows consisting of an alternating load current of the electric mashine and a current of the source 10. The measurement of the direct current flowing through the phase winding 3 is traced The transformer 5, the secondary windings of which through the rectifying device 8 are connected to the measuring device 9. The correction winding 6 of the transformer 5 compensates the variable component of the magnetic flux in the cores of this transformer, caused by the phase winding 3 passing through the primary winding of the transformer 5, because the secondary winding current transformer 4 is proportional to the load current.

High accuracy of winding temperature measurement is ensured by complete compensation of the variable component of the magnetic flux in the cores of transformer 5 while maintaining the current proportionality of the secondary winding of transformer 4. The demagnetizing winding 12 of transformer 4, containing the number of turns equal to the number of turns of the primary winding of this transformer, provides

compensation of the constant component of the magnetic flux due to the passage of the source 10 current through the primary winding of the transformer 4. Capacity 13 protects the source 10 and the demagnetizing winding 12 of the transformer from the alternating current of the supply network.

The proposed device provides measurement with high temperature accuracy.

windings under load of alternating current of electrical machines and devices, and also allows you to unambiguously establish the time of reaching the maximum temperature of the windings, which contributes to reducing the time of the electric machine testing for heating.

Claims (1)

Invention Formula A device for measuring the temperature of a winding of electric machines, comprising a direct current transformer, an alternating current transformer, a rectifying device and a thermal sensor, which uses an electrical masking winding, characterized in that, in order to measure the temperature of the windings under alternating current load, The device additionally contains a DC source connected through a filter to the temperature sensor, and the DC transformer has an additional correction winding unity to the secondary winding of an AC transformer, which in turn comprises additional demagnetizing coil.