MCCB TERM

 Iu

 Rated uninterrupted current (Iu) The rated uninterrupted current of an equipment is a value of current, stated by the manufacturer, which the equipment can carry in uninterrupted duty.

KA rating

kA rating of an MCB or an MCCB is the maximum current it can safely interrupt in case of a short circuit. If the current goes beyond this value, the circuit breaker could be damaged. kA rating is known as the short circuit withstand capacity or ultimate breaking capacity of a circuit breaker

Icu

unlimited break Capacity of the circuit breaker Which means the circuit breaker can break the maximum fault current without damage. Typically for MCB the maximum Icu will be 6KA to 10 KA for MCCB Icu may be 200kAmps.

Ice

Ics is the amount of current that the circuit breaker can safely withstand without being damaged for example 6 kA or 6000 A and remain usable. Icn is the amount of current the circuit-breaker can safely handle but would not remain usable.

Ue

Rated working voltage (Ue) is the continuous operation voltage for which the MCCB is designed. This value is typically equivalent or close to a standard system voltage. Operating short-circuit breaking capacity (Ics) is the highest fault current that the MCCB can trip without being damaged permanently.

Ui

Rated insulation voltage (Ui)

This is the value of voltage to which the dielectric tests voltage (generally greater than 2 Ui) and creepage distances are referred to. The maximum value of rated operational voltage must never exceed that of the rated insulation voltage,

Uimp

Rated impulse-withstand voltage (Uimp)

This characteristic expresses, in kV peak (of a prescribed form and polarity) the value of voltage which the equipment is capable of withstanding without failure, under test conditions. Generally, for industrial circuit-breakers, Uimp = 8 kV and for domestic types, Uimp = 6 kV.