Substation equipment and their functions | Quick Revision | TheElectricalGuy

Summary

Key Points

• —Lightning arrestors are the first equipment seen in a substation and protect all downstream devices from lightning strikes and switching surges by providing a non‑linear resistance path to ground. 1:33
• —Single ACSR conductors are named after animals to indicate their size, and they are used as droppers, busbars, and other conductors within the substation layout. 3:35
• —Capacitive Voltage Transformers (CVTs) step down high line voltages to low levels for accurate metering, relay protection, and also enable power‑line carrier communication because of their internal capacitors. 5:49
• —Wave traps, also called line traps, function as low‑pass filters that block high‑frequency communication signals (40‑500 kHz) while allowing only the power‑frequency (50/60 Hz) to pass into the substation. 8:12
• —Isolators (disconnectors) are employed to isolate sections of the substation for safe maintenance and to re‑route power between primary and backup busbars when a fault occurs. 11:23
• —Current Transformers (CTs) reduce large primary currents to standard secondary values (1 A or 5 A) for metering and protective relay inputs, avoiding the need for oversized equipment. 13:18
• —Circuit breakers act as high‑current switches capable of interrupting short‑circuit currents up to tens of kiloamperes, using SF₆ gas for voltages above 66 kV and vacuum for lower voltages. 15:21
• —Bus post insulators (BPIs) support heavy busbars and prevent excessive mechanical and electrical load on isolator terminals by providing adequate insulation gaps. 16:11
• —Power transformers are the most expensive substation component, stepping voltage up or down while providing electrical isolation between the primary and secondary sides. 18:36