AECO MCBs are calibrated to meet requirements of 18:8828, IEC:898, B8:3871 , VDE:O641 for reference calibration temperature of 3boC. This provides for normal ambient temperatures in tropical/semi-tropical conditions as well as its rise due to mutual thermal effect associated with MCBs when grouped together in distribution boards.

Even otherwise AECO MCBs are designed for minimum calibration variation with respect to temperature. Thus adequate circuit protection is provided over wide range of. ambient temperatures anticipated in normal service without much derating (see curve ).>>>>>

INFLUENCE OF AMBIENT TEMPRATURE

AECO MCBs can also be used on different frequencies in supply from 16²/₃-60 Hz without any derating. For following frequencies, normal MCBs can be used with a multiplication factor which shall only affect its magnetic trip currents.

Multiplication Factor

A C Supply

DC Supply

100 Hz

200 Hz

400 Hz

1.5

In the event of an overcurrent fault occuring within an installation, it is desirable that only the faulty circuit is disconnected from the supply i.e. the nearest downstream device only should operate. For this reason it is necessary for the sub circuit protection to discriminate with other MCBs as well as with the supply intake fuses.

Even though the time-current characteristics of the standard current ratings overlap as per 18:8828, IEC:898, B8:3871 , VDE:O641 , individual ratings of AECO MCBs are calibrated in a narrow band, so that they discriminate with their standard ratings as well.

With their pronounced current limiting characteristics and lower let through energy on account of a unique design, AECO MCBs discriminate with HAC fuses to higher prospective faults than ordinary M6 or M9 MCBs.

As per the wiring regulation, it is required that an overcurrent protection device should be capable of making and breaking any overcurrent upto and including the prospective short- circuit current at the point where the device is installed.

AECO MCBs are capable of making and breaking over currents upto 10000 Amps.

Only if the prospective short-circuit current is expected to be more than 10000 Amps, AECO MCBs require suitable back-up protection e.g. HAC fuses, higher fault capacity circuit breakers etc. AECO service personnel may be consulted for more details.

 Overloading or short-circuit trip in one phase causes all phases to trip simultaneously in AECO multipole MCBs, preventing damage due to single-phasing especially in motor circuits.