GROUNDING TECHNIQUES AND INDUCED SURGE VOLTAGE ON THE CONTROL SIGNAL CABLES

Accurate operation of the metering, control, and protective equipment in the substation relies on dependable input signals. The surge-induce d voltage on the control signal cables during a transient is always a concern of electrical power engineers. However, due to limited space, there are many different kinds of circuits close to each other in an e lectric power substation, Any switching operation or lightning strikes at a substation can cause serious transients with high-frequency osci llatory waveforms to spread through high-voltage circuits, which, in t urn, may give rise to a transient electromagnetic field in the substat ion [1], If a signal control cable runs for some distance in parallel with high-voltage buses, a significant amount of voltage may be induce d. The control, protection, or measurement equipment connected in the low-voltage circuits, in turn, become exposed to these transients. A m ethod of induced-voltage calculation is presented in this paper. The m athematical model of a substation is implemented in the Electromagneti c Transients Program (EMTP) to study the induced voltage during transi ents. The simulation results are compared with field testing results. A recommended grounding practice with the support of computer simulati on and field testing results is also included in this paper.