User manual

Chapter 6 – Configuring Cyber Breaker the Virtual Circuit Breaker
ePower Power Distribution Unit User Manual, Revision 1.1 57
Trip Delay Curve Equation
The trip delay curve equation for t
delay
(represented by the function f(x)) for
any given current (x) above I
min
is:
where variables a, b, c, and d are as described in Table 6-1.
Table 6-1 Trip Delay Curve Equation Variables
Variable Description
Default
Value
a = t
grace
Maximum t
delay
at I
min
400 sec
b
Curve “slope” constant
a
a. Slope “b” is chosen through trial and error, to fit the curve to the desired
values. It is recommended that you first model this in Microsoft Excel,
and play with the values before setting this to a different value.
0.30
c = I
min
Minimum threshold where a Virtual Circuit
Breaker is active
16A
d = t
min
Minimum t
delay
for I
actual
up to I
max
b
b. I
max
is an “instantaneous” drop point. If the current exceeds this value,
Virtual Circuit Breaker uses a grace period of 0 seconds, regardless of
what the equation calculates for f(x).
-1.81 sec
ƒ (C)= a • e
-b(
C
- c )
+ d
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