Chint MN8-1250S/1000/3300 - 1000A molded case circuit breaker

The Chint MN8-1250S/1000/3300 - 1000A molded case circuit breaker is a protective electrical appliance suitable for low-voltage power distribution systems. The following is the relevant introduction:

Model Meaning

- **MN8**: Product series number.

- **1250**: The frame current rating is 1250A, indicating that the maximum long-term operating current that this circuit breaker can withstand is 1250A.

- **S**: Breaking capacity level, usually representing the standard breaking capacity.

- **1000**: The rated current is 1000A, that is, the current allowed to pass through when the circuit breaker is operating normally is 1000A.

- **3300**: The first digit "3" indicates that the number of poles is 3 poles; the second digit "3" indicates that the type of release is a thermal-magnetic release; the last two digits "00" indicate that there are no accessories.

Working Principle  YouTube：https://youtube.com/shorts/zLeW5dsvKTs 

- **Thermal Release**: When there is an overload in the circuit, the current increases, and the thermal element of the thermal release heats up, causing the bimetallic strip to bend. As the overload current continues, the bending degree of the bimetallic strip gradually increases. When it reaches a certain degree, it pushes the free release mechanism to act, causing the main contacts to open and cut off the circuit, thus achieving overload protection.

- **Magnetic Release**: When a short circuit occurs in the circuit, the strong magnetic field generated by the short-circuit current makes the armature of the overcurrent release quickly attracted, driving the free release mechanism to act. The main contacts open quickly, instantly cutting off the short-circuit current and protecting the circuit and equipment from the damage of the short-circuit current.

Main Parameters

- **Rated Operating Voltage**: Usually 230V - 690V, suitable for different low-voltage power distribution systems.

- **Rated Insulation Voltage**: Generally 800V, ensuring that the insulation performance of the circuit breaker can meet the requirements under normal operation and specified overvoltage conditions.

- **Breaking Capacity**: The rated ultimate short-circuit breaking capacity Icu of this model of circuit breaker can reach up to 50kA, which can reliably break the circuit in case of a short-circuit fault and limit the scope of the fault.

- **Mechanical Life and Electrical Life**: The mechanical life is generally 5000 to 10000 times, and the electrical life is 2500 times, reflecting the durability and reliability of the product.

Application Scenarios

- **Industrial Field**: It is used in the low-voltage power distribution system of factories to provide overload and short-circuit protection for various production equipment, motors, etc., ensuring the stable operation of industrial production.

- **Commercial Buildings**: In the low-voltage switchgear rooms of places such as shopping malls and office buildings, it serves as a protective electrical appliance for the power distribution lines, ensuring the safety and reliability of the power supply and preventing accidents such as fires caused by circuit failures.

- **Residential Buildings**: It is also applied in the distribution boxes of some large residential buildings or apartment buildings to protect the electrical lines in the houses and ensure the safety of residents' electricity use.