Test and Analysis on Electromagnetic Disturbance of Digital Unit of Primary–Secondary Integrated 10kV Circuit Breaker

Abstract

The primary side and secondary side of the 10-kV digital circuit breaker is deeply integrated. Wherein, an electronic transformer is deployed together with the breaker inside a cabinet, and a digital unit is closely connected to the output port of the electronic transform. This compact and close arrangement makes the secondary side face a severe electromagnetic environment during the switching operation of the breaker. In this paper, we report the measured electromagnetic disturbances resulting from the opening/closing of 20 kA current by the breaker. The results show that the disturbance voltage at the secondary side port of the voltage transformer has the waveform of damped oscillatory waves, a peak value of up to 1.1kV, and dominant frequencies of 4.4 MHz and 15 MHz. The disturbance voltage at the secondary side port of the current transformer has a peak value of 350 V. The peak value of dH/dt of the spatial magnetic field is 0.387 kA $\cdot \text{m}^{-1}\cdot \mu \text{s}^{-1}$ . By comparing the measured waveforms with these specified in IEC 61000-4-18 and IEC 61000-4-10 standards, we advise that the level of immunity test is the third level of the fast-damped oscillatory wave for voltage port and the fourth level of the damped oscillatory magnetic for enclosure port.

Keywords

• Electromagnetic disturbance
• electromagnetic compatibility (EMC)
• primary and secondary integrated
• switching operation
• short-circuit current breaking
• damped oscillatory wave