NB/T 42107-2017High-voltage direct current circuit-breaker (English PDF)

5.2 Rated current

It shall comply with the provisions of 4.5.1 of GB/T 11022-2011.

5.3 Rated short-circuit current

The DC current expected to be interrupted by the DC circuit-breaker is selected from the following values (kA). 2, 5, 8, 10, 12.5, 16, 20, 25, 31.5, 40, 50, 63, 80, 100, 125.

Note: Where there are special requirements for current, it shall be determined by negotiation between the supplier and the buyer.

5.4 Rated interrupting current

The DC current interrupted by the DC circuit-breaker is selected from the following values (kA). 4, 5, 6.3, 8, 10, 12.5, 16, 20, 25, 31.5.

Note: Where there are special requirements for the current, it shall be determined by negotiation between the supplier and the buyer.

5.5 Maximum continuous operating current

The maximum continuous operating current is generally 1.05 ~ 1.25 times the rated current.

5.6 Insulation level

The rated insulation level of the DC circuit-breaker shall be selected from the values given in Table 1.

5.11 Rated auxiliary and control circuit power supply voltage

Complies with the provisions of 4.9 of GB/T 11022-2011.

6.1 Overview

In DC systems, DC circuit-breakers often use several parallel branches to complete the breaking task. Generally, DC circuit-breakers are composed of three parts.

a) Low-resistance on-state current conducting branch;

b) High-resistance current limiting and commutation branch during the breaking process;

c) Energy absorption branch.

For the mechanical, power electronic, hybrid DC circuit-breakers described in this standard, each has different topological structures and different technical characteristics.

The general topological structures of these three DC circuit-breakers are described in Appendix A.

6.2 General requirements

DC circuit-breakers shall be equipped with open and closed status indicators; their installation locations shall be clearly visible and reliable.

All components of DC circuit-breakers shall be corrosion-resistant or undergo corrosion-resistant treatment.

6.3 Terminal mechanical load

The mechanical load of the wiring terminals in DC circuit-breakers shall not be less than.

- Horizontal longitudinal. 2000 N;

- Horizontal transverse. 1500 N;

- Vertical. 1500 N.

Note 1. See 6.2.3 of GB/T 25309-2010.

Note 2. The wiring load under different voltage levels shall meet the requirements of actual working conditions.

6.4 Creepage distance

It shall be in accordance with actual engineering requirements.

6.5 Auxiliary and control equipment

Comply with the provisions of 5.4 of GB/T 11022-2011 and make the following supplement. For DC circuit-breakers using forced air cooling or water cooling, the relevant requirements of control equipment shall be considered.

6.6 Power operation

Comply with the provisions of 5.5 of GB/T 11022-2011.

6.7 Degree of protection of enclosure

Comply with the provisions of 5.13 of GB/T 11022-2011 and make the following supplement. The degree of protection of enclosure shall not be less than IP23.

6.8 Nameplate

The technical parameters on the nameplate shall at least include the following parameters.

- Rated DC voltage;

- Rated current;

- Rated power consumption.

- Rated short-circuit current (optional);

- Maximum continuous operating current;

- Rated lightning impulse withstand voltage;

- Rated DC withstand voltage;

- Rated interruption current;

7.5 Verification of degree of protection

Conform to the provisions of 6.7 of GB/T 11022-2011.

7.6 Sealing test

Conform to the provisions of 6.8 of GB/T 11022-2011 (when applicable).

7.7 Electromagnetic compatibility test (EMC)

Conform to the provisions of 6.9 of GB/T 11022-2011.

7.8 Mechanical operation test at ambient air temperature

Conform to the provisions of 6.101.2 of GB 1984-2014 and make the following supplement. Only mechanical operation test is carried out on mechanical disconnecting device.

7.9 Terminal static load test

The terminal force shall meet the requirements of 6.3. The test shall be carried out in accordance with the requirements of 6.101.6 of GB 1984-2014.

7.10 Breaking test of DC circuit-breaker

7.10.1 Overview

The purpose of this test is to verify whether the DC circuit-breaker has the ability to break the specified DC short-circuit current.

This test verifies that the DC circuit-breaker can successfully interrupt the DC current within the rated short-circuit current range, and that the interrupter can withstand the recovery voltage between the breaks. According to the actual project requirements, the test circuit shall be equivalent to the actual operating conditions of this type of DC circuit-breaker. The interruption test shall at least include the following requirements.

a) Recommended tests for products above 10 kV, see Table 2;

11.1 Overview

Comply with the provisions of Chapter 10 of GB/T 11022-2011.

11.2 Conditions for transportation, storage, installation

Comply with the provisions of 10.1 of GB/T 11022-2011.

11.3 Installation

Comply with the provisions of 10.2.1 ~ 10.2.4 of GB/T 11022-2011.

11.4 Operation

The instructions provided by the manufacturer shall include the following information.

- General description of the equipment, with particular attention to its characteristics and technical description of operation, so that the user fully understands the main principles involved;

- Description of the safety performance of the equipment;

- Description of the actions taken to operate, isolate, ground, maintain, test the equipment related to operation.

11.5 Maintenance

11.5.1 Overview

The effectiveness of maintenance depends mainly on the content of the instructions written by the manufacturer and the extent to which the user implements the instructions.

11.5.2 Recommendations for manufacturers

The manufacturer shall provide a maintenance manual that includes the following information.

- Scope and frequency of maintenance.

- Detailed description of maintenance work;

- A complete set of drawings of switchgear and controlgear details that are critical to maintenance, with clear markings of general assembly, subassembly, important parts on the drawings;

- Limit values and allowable deviations; if there are deviations, make necessary corrections;

- Specifications of auxiliary maintenance materials, including warnings for known incompatible materials;

- List of special tools, lifting and maintenance equipment.

- Test items after maintenance;

- Recommended spare parts (description, code, quantity) and storage recommendations;

- Estimates of effective planned maintenance time;

- At the end of the operating life of the equipment, how to deal with the equipment, including environmental requirements.

11.5.3 Recommendations for users

If the user wishes to perform maintenance by himself, his staff shall have a detailed understanding of the corresponding switchgear and controlgear.

A.1 Overview

This Appendix applies to DC circuit-breakers for DC transmission with voltage levels of 6 kV and above. The recommended values of the rated parameters of DC circuit-breakers are as shown in Chapter 5 of this standard.

In order to make the DC circuit-breaker suitable for the specified operating task, it shall be selected according to the various rated values required by the load conditions and fault conditions.

A.2 Selection of DC circuit-breaker ratings

A.2.1 Selection of rated DC voltage

The rated DC voltage of the DC circuit-breaker can be selected from 5.1.

A.2.2 Selection of rated current

The rated operating current of the DC circuit-breaker is determined by the rated current of the DC project.

The rated current of the DC circuit-breaker can be selected from 5.2.

A.3 Selection of DC circuit-breaker type

The typical schemes of DC circuit-breakers are. mechanical, power electronic, hybrid.

a) Mechanical DC circuit-breakers are generally composed of breaking device (CB), commutation capacitor (C), commutation reactor (L), commutation switch (G), lightning arrester (MOV), as shown in the dotted box in Figure A.1;

b) Power electronic DC circuit-breakers are generally composed of power electronic components (S) and lightning arrester (MOV), as shown in the dotted box in Figure A.2;

c) Hybrid DC circuit-breakers are generally composed of fast mechanical disconnector (FD), auxiliary DC switch (FS), main DC switch (MS), lightning arrester (MOV), among which the main DC switch and auxiliary DC switch are both power electronic components. As shown in the dotted box in Figure A.3.

DB1 and DB2 in Figures A.1, A.2, A.3 are auxiliary isolation devices used to interrupt residual current. […]