3P 4P Thermal Magnetic Molded Case Circuit Breaker With Overload Protection

Stn2 3p4p Moulded Case Circuit Breaker​

Molded case circuit breakers can have very high current ratings, which allows them to be used in heavy duty applications. The following are some typical uses of an MCCB:

• Main electric feeder protection – The electric feeder circuits that supply power to large distribution boards normally have very high currents, of hundreds of amperes. In addition, if more circuits are added to the system in the future, it may be necessary to adjust the circuit breaker trip settings. Therefore, a molded-case circuit breaker is required.
• Capacitor bank protection – Capacitor banks are a very important component of commercial and industrial electrical systems, since they allow power factor correction – reducing line currents and preventing fees from the electric utility company. Large capacitor banks may draw high currents and will require MCCB protection.
• Generator protection – Large electrical generators may provide an output of hundreds of amperes. In addition, gen-sets are normally very expensive. The high current ratings of molded case circuit breakers allow them to provide reliable protection in this application.
• Welding applications – Some welding machines may draw very high currents that exceed the capabilities of miniature circuit breakers, requiring the use of an MCCB.
• Low current applications that require adjustable trip settings – MCCBs are not only for high current applications. There are models rated below 100 amperes for when low current equipment requires the adjustable trip settings provided by MCCBs.
• Motor protection – The reliable protection capabilities of MCCBs make them an adequate choice for motor protection. A molded case circuit breaker can be adjusted to provide overload protection without tripping during the inrush current of an electric motor.

In summary, an MCCB offers adequate protection whenever an application requires a high current rating, adjustable trip settings, or a combination of both factors.

Note

1. The N-pole breaker has no protection which closing and opening with the other three poles. 2. The type of thermal magnetic for NS-400/630 has no four poles.

1. Overload protection with adjustable threshold, as defined by IEC60947-4 (2) tripping class 10A,10 and 20
2. Short-circuit protection with adjustable threshold (6...13xIr)
3. Phase failure protection (built-in electronic release: operates unbalanced single-phase currentat 40% and more than )(tripping time delay 4s±10%),as defined by IEC60947-4.1
4. Load indication : Flashing more than Ir setting threshold
5. Fault indication

LEDs indicates the type of fault that caused tripping
Overload (LT protection) or abnormal component temperature (>Ir);
Short-circuit (ST or instantaneous protection)( >Im);
Phase failure (right LED);
Microprocessor malfunction ( (>Ir) ( >Im) and phase failure LEDs all go on )
Battery powered. Spare battery are supplied in an adapter box. When a fault occurs ,the LED indicating the type of fault ,lights for about 10 minutes . The information is however stored inmemory . The LED can be illuminated by pressing the test pushbutton. The LED automatically goes off and the memory is cleared when the circuit breaker is reset .