M1-125L/3300 Molded Case Circuit Breaker Co., Ltd.

Published: 2020-08-15 15:12:07

Category: 断路器

Product Description

M1-125L/3300 Molded Case Circuit Breaker

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A molded case circuit breaker automatically cuts off current when it exceeds the trip setting. Molded case refers to using a plastic insulator as the device's housing to isolate conductors and grounded metal parts. Molded case circuit breakers typically contain thermal-magnetic trip units, while larger models may be equipped with solid-state trip sensors. Their trip units are divided into: thermal-magnetic trip and electronic trip units. Commonly used, rated current up to 630 A

Molded case circuit breakers are also known as device-type circuit breakers, where all parts are sealed in a plastic housing. Auxiliary contacts, undervoltage releases, and shunt releases are mostly modularized. Due to the compact structure, molded case circuit breakers are generally not repairable. They are mostly

Molded case circuit breakers are manually operated, and large capacity ones can be electrically opened and closed. Due to the application of electronic overcurrent releases, molded case circuit breakers can also be divided into Class A and Class B. Class B has good three-stage protection characteristics, but due to price factors, Class A products with thermal-magnetic releases have a higher market share. Molded case circuit breakers house the contacts, arc extinguishing chamber, trip unit, and operating mechanism all in a plastic shell, generally not considered for repair, suitable as branch protection switches. Overcurrent releases come in thermal-magnetic and electronic types. Generally, thermal-magnetic molded case circuit breakers are non-selective circuit breakers, only having overload long-time delay and short-circuit instantaneous protection. Electronic molded case circuit breakers have four protection functions: overload long-time delay, short-circuit short-time delay, short-circuit instantaneous, and ground fault. Some newly launched electronic molded case circuit breakers also feature zone selective interlocking. Most molded case circuit breakers are manually operated, and some have motor operating mechanisms.

● Ambient air temperature

○ Upper limit of ambient air temperature +40°C; ○ Lower limit of ambient air temperature -5°C; ○ The average value of ambient air temperature over 24h does not exceed +35°C.

● Altitude: The altitude of the installation site does not exceed 2000m.

● Atmospheric conditions:

The relative humidity of the atmosphere does not exceed 50% when the ambient air temperature is +40°C; at lower temperatures, higher relative humidity is allowed; the monthly average relative humidity of the wettest month is 90%, and at the same time, the monthly average temperature of that month is +25°C, considering condensation on the product surface due to temperature changes.

● Pollution degree: Pollution degree is 3.

Working principle

The main contacts of a low-voltage circuit breaker are closed manually or electrically. After the main contacts close, the free trip mechanism locks them in the closed position. The coil of the overcurrent release and the thermal element of the thermal release are connected in series with the main circuit, while the coil of the undervoltage release is connected in parallel with the power supply.

When a short circuit or severe overload occurs in the circuit, the armature of the overcurrent release is attracted, causing the free trip mechanism to operate and the main contacts to disconnect the main circuit.

When the circuit is overloaded, the thermal element of the thermal release heats up, causing the bimetallic strip to bend, pushing the free trip mechanism to operate, and the main contacts disconnect the main circuit.

When the circuit is undervoltage, the armature of the undervoltage release is released, also causing the free trip mechanism to operate, and the main contacts disconnect the main circuit.

When the shunt release button is pressed, the armature of the shunt release is attracted, causing the free trip mechanism to operate, and the main contacts disconnect the main circuit.

Classification

Low-voltage circuit breakers are classified by the arc extinguishing medium. Circuit breakers using air as the arc extinguishing medium are called air circuit breakers (air switches); those using inert gas as the arc extinguishing medium are called inert gas circuit breakers (inert gas switches); those using oil as the arc extinguishing medium are called oil circuit breakers (oil switches).

Main parameters

(1) Rated voltage

The rated voltage on the circuit breaker nameplate refers to the rated voltage of the main contacts, which is the voltage value that ensures the contacts work normally for a long time.

(2) Rated current

The rated current on the contactor nameplate refers to the rated current of the main contacts, which is the current value that ensures the contacts work normally for a long time.

(3) Trip current

Trip current is the current setting that causes the overcurrent release to operate. When the circuit is short-circuited or the load is severely overloaded, and the load current exceeds the trip current, the main contacts of the circuit breaker open.

(4) Overload protection current-time curve

The overload protection current-time curve is an inverse time characteristic curve. The larger the overload current, the shorter the operating time of the thermal release.

(5) Rated voltage of undervoltage release coil

The rated voltage of the undervoltage release coil must be equal to the rated voltage of the line.

(6) Rated voltage of shunt release coil

The rated voltage of the shunt release coil must be equal to the control power supply voltage.

(7) Rated ultimate short-circuit breaking capacity Icu

There are two indicators for the breaking capacity of circuit breakers: rated ultimate short-circuit breaking capacity Icu and rated service short-circuit breaking capacity Ics.

Note: The above information and technical parameters are compiled and released by Yangzhou Dari Electric Co., Ltd.

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Product Details

M1-125L/3300 Molded Case Circuit Breaker Co., Ltd.