19
Time current tripping characteristics
WavePro
™
low voltage power circuit breaker time current
curves are the engineering documents that define technical
performance characteristics of the devices. Multiples of
circuit breaker trip rating are shown on the top and bottom
horizontal axis, with time in seconds on the vertical axis.
Minimum and maximum clearing time is readily determined
through the characteristic curves. Tripping characteristics
meet ANSI, NEMA and UL standards for rating and calibration.
Table 19.1
Time current curves
Cable terminations
Cables used for low voltage power circuit breaker terminations
in AKD-10 must have minimum 90°C insulation while the
cables’ ampacity will be based on a 75°C rating. This meets
the requirements of ANSI C37.20.1, UL1558 and the National
Electrical Code. Refer to the example for typical cable
ampacities (derating factors that may apply are not shown).
Table 19.2
Example (from NEC Table 310.16)
Cable size
90°C rating (ref.)
75°C rating (of 90°C cable)
500kcmil
430 Amps
380 Amps
600kcmil
475 Amps
420 Amps
Trip device
Trip elements
Curve
REF
Power+
™
MicroVersa Trip Plus
™
MicroVersa Trip PM
™
LSI
DES-001
pg. 20
G
DES-002
pg. 21
MicroVersa Trip Plus
or PM
Non-std. G F
DES-026
pg. 22