SU35276A1 - Device for testing transformer oil and other liquid dielectrics for dielectric strength - Google Patents

Description

The currently used devices for testing transformer oil for dielectric strength in principle consist of a vessel where test oil is poured and in which standard electrodes are fixed, and a high-voltage transformer with a voltage regulator of one or another design that serves variations in voltage applied to electrodes.

Voltage regulation, recording of voltmeter readings and other manipulations require, with the presence of many test samples, considerable time.

The proposed installation automates the entire testing process (with the exception of the oil change) and is characterized by the use of a watch mechanics, periodically including an electric motor, which, in turn, controls the regulating npHcnoco6vieHHeM. The latter is included in the primary winding of the high-voltage transformer and gradually raises it until the breakdown of oil occurs. In this case, the signal device is switched on and at the same time the maximum relay is activated, which turns off the electric motor circuit and the transformer circuit.

The drawing is a schematic representation of the proposed device. The motor 1, by means of a movable lever 2 with a sliding contact 3, controls a regulating device, in this case a potentiometer 4, included in the primary winding of a high-voltage transformer 5. The motor is periodically turned on in an alternating current circuit by means of a clock mechanism 6 using an electromagnetic switch 7 and intermediate blocking relay 8, operating on postbnnom current. To turn off the motor circuit and the transformer circuit during breakdown, the maximum relay 9 acting on the indicated relay 8 is used. Relay 9 is connected to the secondary circuit of the current transformer 10 with a transformation ratio that is changed by branches. The purpose of the current transformer is as follows. Relay 9 is adjusted to a certain operating current, while oil surfing may occur at a voltage such that an increase in the current in the primary circuit of the transformer 6 is not enough to activate the relay. Coefficient change.

transformations makes it possible in all cases of the breakdown to provide a more or less constant starting current for the relay .9. The switching of the branches is carried out by means of a moving contact 11 fixed on the lever 2 moved by the engine. The indicated lever with contacts, after each oil sample, is returned to its initial position by means of a drum 12 with a ratchet mechanism and a spring which is turned when the electric motor rotates. At the end of the lever's path there is a contact device 13 which serves to open, through a relay 8, circuit driving the entire system of the motor in the event that the breakdown does not occur. The test oil is placed in the vessel 14 with electrodes, which is rotated by the indicated drum with a spring after each sample and mixes the oil. The signaling device 15, whose circuit is closed by a clockwork, comes into effect either after the oil has been sampled, in this case after five times, or if the oil is not broken at all. A recording voltmeter 16 can be used to automatically record voltage.

When the device is operating, the clockwork and the mechanism 6 by means of a switch coming in contact with the contact 17 apply a constant voltage to the intermediate relay 8, as a result of which the contacts / 18 of the latter are closed. After a known period of time, the switch 19, going to the right position, closes the solenoid circuit of the electromagnetic switch 7, which in turn closes, through its upper contacts 20, the alternating current circuit of the engine 1 and potentiometer 4. The engine moves the lever 2 connected to the moving contacts. 3 and 1U The voltage of the transformer gradually rises to the breakdown of oil in the vessel 14. At the time of the breakdown, the increased current in the transformer 10 passes through a maximum relay 9, which acts on the relay 8, the contacts 18 of the latter open and break the DC circuit. As a consequence, the AC power supply and its operation

cease. After the breakdown of the lever 2, the spring returns to its original position. The drum at the same time produces rotation of the vessel 14 and the mixing of the oil, than the latter is prepared for the next breakdown. Clockwork 6, after a certain exposure time, for example 2 / .2 minutes, again switches the switch to the left position and the installation starts to operate. In the left position, the switch is for a certain time, in this case 21 / min, min, so that the time between two trials is, for example, 5 minutes.

After a second oil sample, for example, a 5-fold oil, the clock mechanism 6 closes the contacts 21 and, as a result, the circuit of the signaling device 15, giving the signal to change the oil, also closes. After the shift, a pause is made until the next first sample, for example, 10 minutes.

In the event that the oil is not pierced at the maximum voltage of Transformed-Sra 5, the lever 2, reached its extreme position, will close the contacts of the device 13 and, consequently, the electromagnet circuit 22 of the relay 8) which causes the installation to stop working. At the same time, the alarm 15 is activated.

The subject invention ..

Claims (5)

1. A device for testing transformer oil and other liquid dielectrics for dielectric strength, characterized in that for the purpose of automatic repetition of the testing process, a clock mechanism is applied, periodically turning on an electric motor that controls a regulating device gradually increasing the voltage on the primary loan) winding of a high-voltage transformer before the onset of oil breakdown, causing, in turn, switching on of signal devices and simultaneous operation of the maximum th current relay 9 stops the motor circuit and the transformer circuit 5. 2. In the device according to claim 1, use the relay 8 to block the switching on and off of the device. 3. The form of the device according to claim 1, characterized with the use of the TIO sliding lever 2, equipped with a contact 3, sliding on a potentiometer 4, gradually increasing the voltage at the terminals of the transformer-5, and located at the end of the movement path of the contact device 13, opening , when reaching the extreme polozhzhenn, the chain driving the entire system of the electric motor in the event that the breakdown does not occur. 4.- In the device according to paragraphs. 1-3, use a drum 12 with a ratchet mechanism and a spring which is turned when the electric motor 1 rotates and is intended to return the entire system to its original position and at the same time cause the vessel to lie and turn the oil samples to stir the latter. 5. In the device on PP. 1 and 2, in order to ensure that the switching-on relay motor 9 has sufficient starting current, in cases where the breakdown occurs at a reduced operating voltage, the use of an additional sliding contact is fixed on the lever 2 and changes the ratio of the supply relay 9 transformer 10.