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WHAT IS MCB CURVES?

The Trip Curve is a graphical representation of the circuit protection devices. Fuse, MCB’s, MCCB’s, supplementary protectors, motor protection circuit breakers, overload relays, electronic fuses, and air circuit breakers are all examples of circuit protection devices. The multiples of the current going through the miniature circuit breaker are represented on the horizontal X-axis. On a logarithmic scale, the Y-axis displays the miniature circuit breaker tripping time. e characteristic curve indicates the correlation between the current and the tripping time. MCB have: Type B characteristic curves Type C characteristic curves Type D characteristic curves Type K characteristic curves Type Z characteristic curves They’re listed below: The classification of Type B, C, or D is based on the breakdown current rating at which electromagnetic operation occurs to give short-term protection against short circuits. The trip curve is a graph defined between the outgoing current and the tripping time (amp-sec Curve) to provide proper equipment protection and performance and avoiding unwanted tripping. Type B characteristic curves: 3 to 5 times in the magnetic trip for use in household operations when maximum sensitivity is required and there is little equipment that requires significant start up current. When loads are resistive and there is no in-rush current, B curve MCBs should be used. Type C characteristic curves: For commercial and industrial applications, Type C devices are the standard. These devices are designed to trip when the current is 5-10 times the rated current i.e., 50-100A for a 10A electrical device. When loads have a negligible amount of in-rush current on initiation, C curve MCBs should be used. Small transformer load is the ideal application. Type D characteristic curves: The Type D devices have more limited uses, generally in industrial use where high inrush currents can be expected large battery charging systems, winding motors, power transformers, X-ray devices, and certain discharge lighting sources . Type D devices are intended to trip 10-20 times per second i.e., 100-200A / 20A electrical device. Normal connection ratings refer to the amount of time a cable can be used continuously under certain installation conditions. Of course, cables can high currents for a limited time without damage. Type K characteristic curves: The K curve MCB is designed for motor applications where ampere rises quickly and rapidly during “start-up.” Curves can go through the transitory inrush of current and minimise nuisance tripping while providing circuit protection. In less than 0.01 seconds, the magnetic element of the K curve interrupts a short circuit at 10 times of the rated current. At 10 times the rated current, the K curve tripping bandwidth will vary from 0.01 second.