Molded Case Circuit Breaker MCCB

Dongfa Intelligent supplies the GNM1 Series Molded Case Circuit Breaker MCCB for low-voltage power distribution, equipment protection, industrial control cabinets, building distribution systems, and motor circuits. The series covers rated currents from 16A to 1250A, with frame sizes of 63A, 125A, 250A, 400A, 630A, 800A, and 1250A. At 400V, the short-circuit breaking capacity Icu ranges from 25kA to 100kA, with 3-pole and 4-pole configurations available.

Product Features

The GNM1 Series Molded Case Circuit Breaker MCCB is designed to protect low-voltage circuits against overload and short-circuit conditions. Its configuration can be selected according to rated current, system short-circuit current, number of poles, and load type.

Thermal-Magnetic Protection

The thermal-magnetic trip unit provides two protection functions. The thermal element responds to sustained overload current, while the magnetic element provides rapid operation during short-circuit conditions. The typical characteristics include a cold-state non-tripping time of more than 1 hour at 1.05In, a hot-state non-tripping time of no more than 1 hour at 1.3In, and a magnetic trip operating current of 10In±20%.

Multiple Breaking Capacity Levels

The GNM1 Series is available in L, M, and H breaking capacity levels. At 400V, Icu ranges from 25kA to 100kA depending on the frame size and model. This allows the required breaking capacity to be selected according to the calculated short-circuit current at the installation point.

3-Pole and 4-Pole Configurations

Most frame sizes are available in 3-pole and 4-pole configurations. The GNM1-1250M model is available in a 3-pole configuration. The required pole arrangement should be confirmed according to the circuit structure.

Distribution and Motor Protection

Different trip characteristics are available for distribution and motor protection applications. Selected frame sizes support Class 10 and Class 20 motor protection. At 7.2In in the cold state, the operating time is 4-10 seconds for Class 10 and 6-120 seconds for Class 20.

Technical Specifications

The main specifications of the Molded Case Circuit Breaker MCCB series are shown below. Select the specific model according to rated current, breaking capacity, poles, and application requirements.

MCCB Selection Guide

Selecting a Molded Case Circuit Breaker MCCB requires checking the normal load current, frame size, expected short-circuit current, pole configuration, load type, and installation environment.

Rated Current and Frame Size

The rated current should be selected according to the normal operating current of the load. The GNM1 Series provides frame sizes of 63A, 125A, 250A, 400A, 630A, 800A, and 1250A. For installation in high-temperature enclosures, the corrected operating current should also be considered.

Short-Circuit Breaking Capacity

The required Icu should be determined from the expected short-circuit current at the installation point. The GNM1 Series covers 25-100kA at 400V, with different L, M, and H levels available for different system requirements.

Pole Configuration

Select 3P or 4P according to the circuit structure. A 3-pole configuration can be used for applicable three-phase circuits, while a 4-pole configuration can be selected where the neutral conductor also needs to be controlled.

Load Type

Distribution circuits should use the corresponding distribution protection characteristics. For motor circuits, the starting time and load conditions should be checked before selecting Class 10 or Class 20 protection.

Ambient Temperature

The thermal trip characteristics are affected by ambient temperature. For GNM1-250, the correction factor is 1.00 at +40°C, 0.96 at +45°C, 0.91 at +50°C, 0.87 at +55°C, and 0.82 at +60°C. For example, a 250A frame at +50°C has a correction factor of 0.91, giving a corrected current of approximately 227.5A. The actual cabinet temperature should be used for final selection.

Altitude

For installations above 2000m, both operating current and short-circuit breaking capacity require correction.

Breaking Capacity Correction

For example, a product with a 50kA Icu at 400V would have a corrected breaking capacity of approximately 35.5kA at 4000m when the 0.71 correction factor is applied.

Applications

The Molded Case Circuit Breaker MCCB is suitable for low-voltage distribution systems where overload and short-circuit protection are required.

Building Power Distribution

The GNM1 Series can be used in main and branch circuits of building low-voltage distribution systems. The rated current and breaking capacity should be selected according to the load and system short-circuit conditions.

Industrial Control Cabinets

The product can be installed in industrial control cabinets and equipment distribution circuits to provide circuit protection for connected electrical loads.

Motor Circuits

Selected models with motor protection characteristics can be used in motor circuits. Class 10 or Class 20 should be selected according to motor starting time and actual load conditions.

Equipment Power Distribution

The series can also be used for industrial equipment and other low-voltage electrical distribution circuits where the required current and short-circuit protection are within the product range.

Wiring and Recommended Conductor Size

1.5mm² 2.5mm² 4mm² 6mm² 10mm² 16mm² 25mm² 35mm² 50mm² 70mm² 95mm² 120mm² 185mm² 240mm²

Final conductor selection should also consider the installation method, ambient conditions, allowable current-carrying capacity, and applicable electrical standards.

Replacement and Customization

For replacement projects, Dongfa Intelligent can review the required configuration according to the original breaker model, rated current, breaking capacity, pole configuration, mounting dimensions, and quantity.

Providing the original model and mounting dimensions helps confirm whether the selected GNM1 model is suitable for the existing installation space and circuit requirements. Custom requirements can be reviewed according to the application and technical specifications.

Manufacturing and Testing

Factory Testing

Before shipment, products undergo mechanical operation testing, trip characteristic testing, and dielectric withstand testing. These tests verify the operating mechanism, protection characteristics, and insulation performance of the finished product.

Management System

The company operates under ISO 9001, ISO 14001, and ISO 45001 management systems and supports factory audits.

Supply Information

Standard products have a lead time of 7-15 working days, while customized products generally require 15-30 working days. Standard products support a minimum order quantity of 1 unit. Final lead time is confirmed according to product specifications, customization requirements, and order quantity.

FAQ

1. What is the product used for?

A Molded Case Circuit Breaker MCCB is mainly used for overload and short-circuit protection in low-voltage distribution circuits. When sustained overload or short-circuit conditions occur, the breaker disconnects the circuit to reduce the impact on cables and connected electrical equipment.

2. What is the rated current range of the GNM1 Series?

The GNM1 Series covers rated currents from 16A to 1250A. Frame sizes include 63A, 125A, 250A, 400A, 630A, 800A, and 1250A, with the exact current range determined by the selected model.

3. How should the breaking capacity be selected?

The required breaking capacity should be based on the expected short-circuit current at the installation point. At 400V, the GNM1 Series provides Icu values from 25kA to 100kA, depending on the frame size and model.

4. How do I choose between 3P and 4P?

Select 3P or 4P according to the circuit structure. A 3-pole configuration can be used for applicable three-phase circuits, while a 4-pole configuration can be selected where the neutral conductor also needs to be controlled.

5. What should be considered when using the breaker at high altitude?

Above 2000m, the operating current and short-circuit breaking capacity require correction. At 4000m, the operating current correction factor is 0.88 and the breaking capacity correction factor is 0.71.

6. Does the GNM1 Series support motor protection?

Selected models support motor protection with Class 10 and Class 20 trip characteristics. The appropriate model should be confirmed according to motor starting time and load conditions.

7. What information is required for a quotation?

Please provide the rated current, frame size, required breaking capacity, pole configuration, load type, and quantity. For replacement projects, the original breaker model and mounting dimensions are also recommended.

Get a Quote and Selection Support

Send the rated current, frame size, breaking capacity requirement, pole configuration, load type, and quantity. For replacement projects, include the original breaker model and mounting dimensions so the required specification can be checked before quotation.

Dongfa Intelligent can provide product selection and quotation support according to the project requirements.