Series capacitors are a well established concept within electric power transmission, finding ever increasing use in EHV and UHV transmission grids to provide benefits such as improved voltage and transient stability of long lines as well as improved power division between parallel lines. Series capacitors in a transmission line can have a significant effect on the transient voltage that appears across the contacts of a circuit breaker when opening to clear a fault and the series capacitor into the line makes the line protection more complex due to the abrupt change in line series impedance at the series capacitor. These topics are discussed in this paper.