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
- 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
- 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
In summary, an MCCB offers adequate protection whenever an
application requires a high current rating, adjustable trip
settings, or a combination of both factors.
(ambient temp +40°C)
1.05In(cold state) in
(ambient temp +40°C)
1.0 In(cold state)
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
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 .