For ACB / MCCBs :
Parameter | Symbol | Description |
---|---|---|
Voltage | Ue | Rated operational voltage |
Ui | Rated insulation voltage | |
Uimp | Rated impulse withstand voltage | |
Current | In | Rated Current |
Ith | Conventional free air thermal current | |
Ithe | Conventional enclosed thermal current | |
Short Circuit | Icm | Rated short-circuit making capacity |
Icu | Rated ultimate short-circuit breaking capacity | |
Ics | Rated service short-circuit breaking capacity | |
Icw | Rated short-time withstand current | |
Utilization | Category A | Circuit Breaker wihout short Time withstand Icw capacity are Calassified as Category A. Utilization Category A breakers are Current Limiting. |
Category B | Circuit Breaker with Short Time withstand Icw capacity are Calassified as Category B. Utilization Category B breakers are Selective (non current limiting) | |
Trip Unit | In | Rated Current of Breaker |
Ir | ANSI 49 – Long time Adjustable overload setting current | |
1.05 x Ir | Conventional non-tripping current | |
1.30 x Ir | Conventional tripping current | |
tr | Long time delay setting | |
Isd | ANSI 51 Short time delay tripping setting current | |
tsd | Short time delay setting | |
Ii | ANSI 50 Instantaneous tripping setting current | |
Ig | ANSI 51N Earth fault tripping setting current | |
tg | Earth fault time delay setting | |
Igl | ANSI 51G Earth Leakage tripping setting current |
For MCB :
Parameter | Symbol | Description |
---|---|---|
Voltage | Ue | Rated operational voltage |
Ui | Rated insulation voltage | |
Uimp | Rated impulse withstand voltage | |
Current | In | Rated Current |
Magnetic tripping | B curve | 4 x In |
C curve | 8 x In | |
D curve | 12 x In | |
Utilization | Category A | Circuit Breaker wihout short Time withstand Icw capacity are Calassified as Category A. Utilization Category A breakers are Current Limiting. |
Limitation class | 3 B Curve | I2t – A2S, 70000 upto 16Amps I2t – A2S, 90000 upto 16 to 32Amps |
3 C Curve | I2t – A2S, 84000 upto 16Amps I2t – A2S, 110000 upto 16 to 32Amps | |
Pollution degree | 3 | Conductive and non-conductive pollution present. Condensation frequent. |
Over Voltage Category | IV | Uimp=6KV, Ue Line to Neultal = 300V |