JP2001035724A - High withstand voltage dc current flowing transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high withstand voltage DC current flowing transformer which outputs a DC current necessary for current applying test of a cable with a DC high voltage. SOLUTION: Transformers 1, 2, 3 are arranged on insulation pedestals 4, 6, 8 and are cascaded via bushings 41, 42. An AC current is inputted in the transformer 1 of the lowermost layer, a rectifier 9, a smoothing capacitor 10 and a smoothing coil 11 are connected with the output of the transformer 3 of the uppermost layer, and a DC current is outputted. Then by grounding the insulating pedestal 4 of the lowermost layer and a sheath 23 of a cable 20, a DC high voltage can be applied between the sheath of the cable 20 and a core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high withstand voltage DC current transformer, and more particularly to a high withstand voltage required for testing the DC current carrying characteristics of a submarine cable for transmitting DC power, and capable of outputting DC current. The present invention relates to such a high withstand voltage DC current transformer.

[0002]

2. Description of the Related Art At present, the voltage for direct current transmission through a submarine cable is about 800 kV. Usually, an iron wire is wound around the outer circumference of a submarine cable in order to prevent damage and protect the cable core from internal and external pressures. For this reason, when conducting an energization test using an AC energizing transformer, the outer peripheral iron wire receives electromagnetic induction and generates heat due to hysteresis loss. Temperature characteristics will be different. For this reason, in order to perform a test for applying a voltage to a cable for DC power transmission, it has a withstand voltage value of DC 1000 kV to 2000 kV,
A high withstand voltage energizing transformer capable of passing a current of about 0 to 5000 A DC is required.

[0003]

However, there is no such transformer in the past. The reason is that in order to obtain a direct current, it is necessary to rectify an alternating current with a rectifier, but only a rectifier having a withstand voltage of 1 kV or less exists.

[0004] Therefore, a main object of the present invention is to connect the transformer windings of a plurality of transformers in series and share the applied voltage with the transformers to reduce the voltage applied to the rectifier to a predetermined voltage or less. Accordingly, it is an object of the present invention to provide a high withstand voltage DC conduction transformer capable of supplying a DC current while applying a high DC voltage.

[0005]

The invention according to claim 1 is
A DC current-carrying transformer for energizing a cable by applying a high DC voltage to the cable for an energization test of the cable, wherein each of the at least two frames is insulated and stacked, and each of the frames is disposed on the frame. , Each of which is connected in cascade to receive an AC voltage in the lowermost layer, and connected to an output side of the uppermost layer transformer to rectify the AC voltage into a DC voltage and supply a current to one end of the cable. A rectifier circuit is provided, and the lowermost frame and the cable jacket are grounded.

According to the second aspect of the present invention, a voltage dividing resistor for measuring a shared voltage of each stage is provided between the respective frames of the first aspect.

[0007]

FIG. 1 is a diagram showing a current-carrying transformer according to an embodiment of the present invention. In this embodiment, DC 10 kV is applied to a cable as a sample while DC 630 kV is applied.
A description will be given of an energizing transformer for energizing 00A as an example. The windings of three insulating transformers 1, 2, 3 are connected in series,
Cascaded and integrated. The output of the transformer 1 and the input of the transformer 2 and the output of the transformer 2 and the input of the transformer 3 are connected by bushings 41 and 42, respectively. The bushing is a rod that has an outer case made of an insulator and an insulator, and has an integrated structure filled with an insulating oil and an insulator inside, and through which the output wires are passed.

The transformer 1 has, for example, an input of 200 V and an output of 4
It is 00 V, has a withstand voltage of 350 kV, and is arranged on the insulating gantry 4, and the insulating gantry 4 is grounded. An insulating gantry 6 insulated by an insulator 5 is installed on the insulating gantry 4, and the transformer 2 is arranged on the insulating gantry 6. Transformer 2
Has an input of 400 V, an output of 400 V, and a withstand voltage of 350 kV. An insulating gantry 8 insulated by an insulator 7 is installed on the insulating gantry 6, and the transformer 3 is mounted on the insulating gantry 8. The transformer 3 has an input of 400 V, an output of 25 V, and a withstand voltage of 4 kV.

The voltage of 25 V AC output from the transformer 3 is applied to a rectifier 9 and rectified to form a pulsating current. The current is smoothed by a smoothing capacitor 10 and a smoothing coil 11 and a current of 1000 A is applied at a voltage of 20 V DC. Is output and the test cable 20 is energized. In the test cable 20, the core wire 21 is covered with an insulator 22, and the insulator 22 is covered with a jacket 23, and the jacket 23 is grounded.

As described above, by cascading the transformers 1, 2 and 3 and arranging the transformers on the insulating frame, the 704 of 350 + 350 + 4 kV between the high voltage portion of the sample and the ground is provided.
A withstand voltage of kV can be provided, and the withstand voltage can be sufficiently satisfied by a withstand voltage test of 630 kV in the withstand voltage test device 40. If the voltage applied to the sample is to be increased, an insulating transformer or an insulating gantry may be added.

Each of the insulating bases 4, 6 is provided with a voltage dividing resistor 31, 32 for measuring a voltage.

The embodiment disclosed this time is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0013]

As described above, according to the present invention, at least two insulating frames are stacked, a transformer is arranged on these frames, and the input and output of the transformer are cascade-connected. An AC is input to the transformer, the output of the top transformer is rectified, and a DC current is supplied to the test cable, so that a high withstand voltage DC current, which could not be obtained conventionally, can be easily obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a diagram showing a current-carrying transformer according to an embodiment of the present invention.

[Explanation of symbols]

1,2,3 Insulation transformer, 4,6,8 Stand, 5,7
Insulators, 9 rectifiers, 10 smoothing capacitors, 11 smoothing coils, 20 test cables, 31 and 32 voltage dividing resistors,
40 withstand pressure tester, 41, 42 bushing.

Claims (2)

[Claims] 1. A high withstand voltage direct current transformer for supplying a direct current for a high voltage application test in an electrical performance test of a cable, comprising at least two pedestals each insulated and laminated. Transformers arranged on each stand, each connected in cascade, and an AC voltage is input to the lowermost layer, and connected to the output side of the uppermost transformer among the transformers to rectify the AC voltage to a DC voltage. A rectifier circuit for energizing one end of the cable, and grounding the lowermost gantry and a jacket of the cable. 2. The high withstand voltage direct current transformer according to claim 1, wherein a voltage dividing resistor for measuring a voltage is provided between each of the mounts.