Molded Case Circuit Breaker (MCCB)
Definition and Function:
A molded case circuit breaker (MCCB) is an electrical protection device primarily used in low-voltage power distribution systems. Its functions include:
Automatically cutting off current, especially when it exceeds the set trip value.
Connecting, carrying, and disconnecting current under normal conditions, while swiftly disconnecting under abnormal conditions like overload and short circuit to ensure circuit safety.
Scope of Application:
MCCBs are suitable for DC power grid circuits with rated voltages ranging from DC 250V to DC 1000V and rated currents from 10A to 1250A. They offer:
Overload protection with long delay.
Short circuit protection with instantaneous response, essential for distributing electrical energy and safeguarding lines and power equipment from faults.
Structural Features:
Key features of MCCBs include:
Fast closing and disconnecting functions in their operating mechanism.
Compact structure, small size, and ease of use.
Contact arc extinguishing system with moving and static contacts designed on the principle of parallel conductors. Static contacts (H-type) can be separated quickly during high currents.
Components surrounding moving and static contacts made from high arc-resistant materials to facilitate rapid arc extinguishing.
Conditions of Use:
For optimal operation, MCCBs require:
Installation altitude below 2000m.
Ambient air temperatures not exceeding +40℃ or falling below -5℃, with a 24-hour average not surpassing +35℃ (excluding special orders).
Relative humidity at the installation site not exceeding 50% at +40℃, with higher levels permissible at lower temperatures.
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