Product Introduction

The DDXK3 Lightweight High-Speed Current-Limiting Circuit Breaker is a high-current current-limiting circuit breaker with a rated current of ≤630A. It consists of a specially designed current-limiting fuse connected in parallel with a special arrester. The current-limiting fuse has a rated short-circuit breaking current of 100kA and has passed the certification test of the National High-Voltage Electrical Equipment Quality Inspection and Testing Center. The special arrester with a gap functions to limit overvoltage, absorb overvoltage energy, and accelerate the arc-extinguishing speed of the fuse.

Main Features

• It is used in places with small rated current but large short-circuit current, such as high-voltage transformer circuits in generator plants, exciter/excitation transformer circuits on generator branch busbars, PT (potential transformer) circuits of generator branch busbars, and outlet of substation feeders.

• Usually, the DDXK3 is used in a cabinet in series with a circuit breaker (or load switch). In the case of small short-circuit current, the circuit breaker or load switch trips; when a large-amplitude short-circuit current occurs, the special current-limiting fuse of DDXK3 acts quickly to break and limit the short-circuit current, protecting the main equipment from short-circuit damage. After any phase of the fuse acts, its striker triggers the linkage relay through the flexible linkage device, and then its contact triggers the three-phase tripping of the main circuit breaker or load switch to avoid non-full-phase operation. The triggering opening time has sufficient margin to ensure that the main switch trips only after all fuses in two or three phases are completely broken.

Main parameters

• Rated voltage: 7.2~12kV

• Rated current: 100~630A

• Breaking time: 3~5ms

• Current limiting coefficient: 15%~50%

• Rated short-circuit breaking current: 63~100kA

Main uses

• It is used for fast short circuit protection of generators, plant high variables, and generator branch buses, limiting and quickly interrupting high-amplitude short-circuit currents to prevent short circuit damage of generators and transformers;

• It is used for the rapid disconnection of feeders prone to short circuit faults and the rapid isolation of fault points, so as to prevent the bus voltage drop caused by the feeder short circuit fault, which will cause a large area of low-voltage tripping and power outages.