User manual

Chapter 6 – Configuring Cyber Breaker the Virtual Circuit Breaker
56 ePower Power Distribution Unit User Manual, Revision 1.1
Theory
Each Virtual Circuit Breaker operates according to a trip-curve
equation that relates actual current to trip delay time, resulting
in the following features:
• Limits over-current conditions to a single outlet
• Turns Off an outlet when the amperage exceeds a user-defined
threshold
• Decreases trip delay time as current increases
A Virtual Circuit Breaker behaves according to the following algorithm:
• From 0A to the user-defined current threshold (I
min
), a Virtual Circuit
Breaker does not trip
• At the rated current load (I
min
), the trip delay equals t
grace
• Trip delay decreases per the user-defined curve as current increases
• At 34A (I
max
), the trip delay equals t
min
• Above I
max
, a Virtual Circuit Breaker trips instantaneously
NOTE UL 489A (10
th
edition) defines an “instantaneous trip” as “a qualifying
term indicating that no delay is purposely introduced in the automatic tripping
of the circuit breaker.”