Free Tool · IEC 60255-151

Substation Protection Coordination

Check time-current selectivity across your substation protective device chain. Evaluates coordination margins (≥ 0.2 s), inrush restraint, backup protection, and generates a log-log coordination plot per IEC 60255-151.

Transformer
Upstream Source
Downstream Cable
Protective Devices
# Type Rating (A) Curve I_s (A) t_s (s)
1
2
3
Add protective devices below to check selectivity.