ITE K-600 Circuit Breaker Question 1

[wbd]

I have an ITE Power Circuit Breaker K-600 and I am confused on the nameplate Short Circuit Current ratings. One part of the nameplate lists:
600Vac - 22000A
480Vac - 30000A
240Vac - 42000A
But another place on the nameplate states Short Time Current 22000A.

Can someone explain what the Short Time Current rating is? There appears to be a Time component with that rating versus the instantaneous ratings. If so, what amount of time?

Nameplate picture attached.

 

[GroovyGuy]

Per the description below, the time duration for the "short circuit" rating is 3s (ie the Icw rating). I believe that is the same time duration used for ANSI rated CBs as well. Perhaps someone else can comment on that?
Low Voltage Circuit Breakers
Based on IEC 60947-2 (LV switchgear and controlgear - Part 2: Circuit breakers):
In (Rated current)
The rated continuous / uninterrupted current that the circuit breaker can carry.
Icm (Rated short-circuit making current)
The short-circuit current that the circuit breaker can withstand as it is closing where the act of closing initiates the fault.
Icu (Rated ultimate short-circuit current)
The maximum symmetrical short-circuit current the circuit breaker can interrupt.
Ics (Rated service short-circuit current)
The breaking capacity such that the circuit breaker is tested to carry its current continuously. The test sequence verifies that the breaker can be returned to service. Ics is the maximum current the breaker can interrupt multiple times and be returned to service without being damaged and is expressed as a % of Icu.
Icw (Rated short time withstand current)
This is the steady state symmetrical fault current the breaker has to be able to carry for a duration of 0.05s to 3s without exceeding its thermal integrity
GG

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[wroggent]

ANSI 600V would be 0.5 seconds.

 

[GroovyGuy]

Howdy wroggent;
I believe that you are correct; the short time rating for lv circuit-breakers is 30 cycles. The 3s rating is applicable for mv breakers.
GG

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[dpc]

Agree with wrrogent - the short time rating is a 30 cycle rating.