Rated breaking current vs small inductive breaking current rating
Rated breaking current vs small inductive breaking current rating
(OP)
Hi friends,
My EHV CB (rated 145 kV) is rated for breaking capacity 40 kA. But the reactor breaking current is only 315 A.
Also, the Cable charging current breaking capacity is 160A only. However, the Back to Back Capacitor Switching current breaking capacity is 400A. Why the current values differ over such a high value from kA to A range ? Also what is the difference in breaking cable charging and capacitor switching currents?
Thnks
My EHV CB (rated 145 kV) is rated for breaking capacity 40 kA. But the reactor breaking current is only 315 A.
Also, the Cable charging current breaking capacity is 160A only. However, the Back to Back Capacitor Switching current breaking capacity is 400A. Why the current values differ over such a high value from kA to A range ? Also what is the difference in breaking cable charging and capacitor switching currents?
Thnks






RE: Rated breaking current vs small inductive breaking current rating
1. Interrupting inductive & capacitive loads are much more difficult than resistive loads.
2. The 40 kA fault rating is designed to be used just a few times, whereas the switching rating might allow for thousands of operations. For one of our 2000A/ 40kA breakers, inspection is required at:
Amps - Inspection period
40000 10 operations
20000 30 operations
10000 100 operations
2000 2000 operations
RE: Rated breaking current vs small inductive breaking current rating
RE: Rated breaking current vs small inductive breaking current rating
The IEEE/IEC consensus standards are developed with typical applications in mind, and do not necessarily spell out the information needed to determine if your circuit breaker will work in this application. You are dealing with a highly specialized situation and will probably need to enlist the aid of your circuit breaker manufacturer and/or a simulation expert. In order to meet both IEEE and IEC requirements, the manufacturer probably went above and beyond the standard values on the nameplate stamp. For example, a breaker model we purchased passed design tests at 46 kA, but was nameplated down to 40 kA to match the IEEE "preferred" interrupting ratings.
It is quite possible that breakers with identical nameplate ratings would react very differently to your waveform.
RE: Rated breaking current vs small inductive breaking current rating
Sorry for the details spread over different threads. Will take care.
RE: Rated breaking current vs small inductive breaking current rating
RE: Rated breaking current vs small inductive breaking current rating
Thanks
RE: Rated breaking current vs small inductive breaking current rating