Hitachi Relion 650 Series Technical Manual page 300

Section 12
Monitoring
Vm
3Vm
‐Vm
‐5Vm
2Vm
‐4Vm
IEC19000917 V1 EN-US
Figure 136: Re-strikes on a capacitive load
When de-energizing a reactive load, re-ignitions occur essentially because of current chopping,
which refers to interruption of the current prior to its natural current zero. This is due to the small
inductive currents, which are interrupted by a high-power circuit breaker. The steep current gradient
of chopping initiates high-amplitude and high-frequency voltage oscillations between reactor
inductance and stray capacitances. Thus, the TRV (voltage across the interrupter gap) rises very
quickly, as shown in
294
Current
Vm
Capacitor
Vm
Figure 137.
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Source
voltage
voltage
Voltage across
the breaker
1MRK 511 557-UEN Rev. A
Re‐strikes
time
time
Dielectric strength
across breaker
time
IEC19000917-1-en.vsdx
Technical Manual