Lightning transients in control lines at the large urban area HV substation

In the HV substation, damage to or malfunction of the electrical and electronic equipment is very often caused by switching operations in primary circuits, earthing faults and lightning strokes. Electronic devices are very sensitive for any transient state. A direct lightning stroke into an open air high-voltage substation is considered. In this case, lightning current flows through conductive-earthed structures above ground and in earthing grids. This current induces voltage and current in low-voltage cables, which can cause severe problems in control, measurement and secondary circuits. The paper presents a computer analysis of lightning transients induced in low voltage wiring in the case of lightning strikes in the area of the substation.