MCCB refers to a molded case circuit breaker used to protect a low-voltage circuit with a rating of 600VAC or less and 750VDC or less. An MCCB can be used to turn an electric circuit “ON” and “OFF” and can protect the circuit. MCCB has many advantages and disadvantages for the circuits.
Advantages of MCCB
The benefits of MCCB are the following:
- MCCB protects circuits against overloads and short circuits. It is a safety device.
- MCCB covers current ratings between 15 A and 2500 A and interrupting ratings, at 480 V AC, which can reach 150 kA.
- MCCB ensures high performances in extremely small and compact dimensions.
- Thanks to the double insulation technique, the electrical accessories can be mounted directly on the field with the circuit breaker installed. This allows considerable savings in time and therefore in costs.
- MCCB could have electronic to the thermomagnetic trip units. You can adjust current and time values using trip units.
- MCCBs are also available in all versions: fixed, plug-in, and draw out and, thanks to special kits, passing from a fixed circuit breaker to a plug-in/draw-out one is easy.
- MCCBs are complemented by a complete range of accessories to satisfy the widely differing operational and automation requirements.
- MCCBs can be used in ambient conditions where the surrounding air temperature varies between –13 °F and +158 °F (–25 °C and +70 °C) and stored in ambient with temperatures between –40 °F and + 158 °F (–40 °C and +70 °C)
- Molded case circuit breakers can be installed in the switchboards, mounted in any horizontal, vertical, or lying down position on the backplate or on rails, without undergoing any derating of their rated characteristics.
- MCCB has a wide range of application areas. The market size of MCCBs is extremely large.
- MCCB is a developing technology. The protection features are extending year by year.
- MCCB has a long lifespan. The average lifetime of an MCCB is around 20 years.
- Electronic versions can communicate with other MCCBs.
- It does not affect the characteristics of the circuit breaker at an altitude of less than 2,000 m.
- Even if the overcurrent flows only to one pole, all poles are simultaneously disconnected, so there is no possibility of phase failure.
- After removing the cause of the accident, the MCCB only needs to be closed again. No extra steps or procedures are required for recovery as with the fuse.
- Remote operation is possible by operating the electricity. Elements required for automatic control, including the undervoltage trip, voltage trip, auxiliary switch and alarm switch, etc.
Disadvantages of MCCB
The drawbacks of MCCB are the following:
- The cost of MCCB can be expensive compared to MCB and fuse.
- The maintenance of an MCCB is not easy. Because it has an insulated case. It is hard to reach internal busbars and arching chambers.
- The installation time of an MCCB is not short. When installing an MCCB, safety clearances must be kept among the breakers, panels, busbars and other protection devices installed nearby.
- If you use lots of MCCB inside a panelboard, it requires cooling.
- It operates very fast as soon as it detects a short circuit but it is not fast in overloads.
- Dust and corrosion could affect its performance.
- You need lots of space in your warehouse if you want to stock lots of MCCB.
- The excessive vibration makes some troubles in the breakage of a circuit breaker, the dynamic strength of failure, electric current, carrying, and the safety operating characteristics so, choosing the circuit breaker, you need proper consideration of this environmental stress.
- The IP rating of an MCCB is not high.