Explain Series capacitors

These are connected in series with the line conductors and are used to reduce the inductive reactance of long transmission lines and hence the voltage drop. A major drawback is that short-circuit currents cause excessive voltages across the capacitors and special protective devices such as spark gaps are required to protect them. Also, they increase the system fault level.

It is important to note that by using series capacitors, the power transmission capability of a transmission line is increased, as:

P = V_S V_R / X (1-K) sin δ

Where the compensation level  (k)  is  X_capacitor / X_line