Product Overview

The Schneider MT25H2 MasterPact Circuit Breaker Frame is a high-current air circuit breaker assembly used in low-voltage power distribution systems. It belongs to the MasterPact NW25H2 product configuration, which is rated for 2500 A and provides high short-circuit interruption performance for industrial and commercial electrical installations.

The MT25H2 configuration is associated with the MasterPact NW circuit breaker platform. Its primary function is to provide circuit protection by interrupting electrical current when overloads or short circuits occur. The H2 performance level provides a rated ultimate short-circuit breaking capacity of 100 kA at 440 V AC.

The MasterPact circuit breaker is suitable for applications involving large distribution boards, industrial switchgear, and main power supply systems. It supports fixed mounting arrangements and three-pole electrical distribution configurations.

The circuit breaker can be integrated into low-voltage switchboards where high current-carrying capacity and coordinated circuit protection are required. Its protection arrangement can be combined with compatible control and protection accessories according to the selected equipment configuration.

For replacement and equipment maintenance, the complete MasterPact NW25H2 configuration should be checked against the existing switchgear arrangement, including rated current, breaking capacity, pole configuration, mounting type, and control unit requirements.

Technical Specifications

Product Features

• 2500 A Current Rating: Supports high-current power distribution applications in industrial and commercial electrical installations.
• H2 Breaking Performance: Provides a rated ultimate short-circuit breaking capacity of 100 kA at 440 V AC.
• Three-Pole Configuration: Supports three-phase electrical distribution and circuit protection.
• MasterPact NW Platform: Belongs to Schneider Electric’s high-current air circuit breaker product family.
• Fixed Mounting Arrangement: Supports installation in compatible low-voltage switchgear assemblies.
• Isolation Capability: Supports electrical isolation in accordance with the applicable IEC 60947-2 requirements.
• Protection Coordination: Can be integrated into distribution systems requiring coordinated overload and short-circuit protection.
• Accessory Compatibility: Supports compatible MasterPact accessories according to the selected circuit breaker configuration.

Working Principle

The MasterPact NW25H2 operates as an air circuit breaker that monitors the electrical current flowing through the protected circuit.

During normal operation, current passes through the main contacts of the breaker to supply downstream electrical equipment. The circuit breaker remains closed while operating conditions stay within the permitted protection limits.

When an overload or short circuit occurs, the associated protection system detects the abnormal current condition and initiates the opening mechanism. The main contacts separate, interrupting the electrical circuit.

During contact separation, an electrical arc forms between the contacts. The air arc-extinguishing arrangement controls and extinguishes this arc, allowing the circuit to be interrupted safely within the specified breaking capacity.

The H2 performance configuration provides a 100 kA ultimate short-circuit breaking capacity at 440 V AC. This capability makes the breaker suitable for distribution installations where high prospective fault currents must be interrupted.

Typical Protection Sequence:

Incoming Power Supply → MasterPact NW25H2 Circuit Breaker → Protected Distribution Busbar → Downstream Electrical Loads

After a fault interruption, the cause of the trip should be investigated before the breaker is returned to service. Resetting the mechanism without identifying the fault may expose the electrical installation to repeated short-circuit or overload conditions.

Role in Schneider MasterPact Power Distribution Architecture

The MT25H2 serves as a main or distribution-level circuit protection device within compatible MasterPact NW switchgear arrangements.

In a typical low-voltage distribution system, the breaker is installed between the incoming power supply and the downstream distribution busbar. It provides the switching and interruption capability required to isolate electrical circuits during abnormal operating conditions.

Its 2500 A current rating and H2 interruption performance make it suitable for large industrial distribution installations.

Industrial Applications

Installation and Maintenance

1. Verify Model Configuration: Confirm that the replacement is compatible with the existing MasterPact NW25H2 installation, including rated current, breaking capacity, and pole arrangement.
2. Check Switchgear Compatibility: Verify the fixed mounting arrangement and the mechanical dimensions required by the existing switchgear assembly.
3. Isolate the Power Supply: Disconnect the upstream power source and apply the required lockout and tagout procedures before maintenance.
4. Verify Absence of Voltage: Use an appropriately rated voltage tester to confirm that all relevant electrical connections are de-energized.
5. Inspect Main Connections: Examine the incoming and outgoing electrical connection points for overheating, oxidation, corrosion, or mechanical damage.
6. Check Protection Configuration: Verify the installed protection unit and its settings against the electrical coordination requirements of the distribution system.
7. Inspect Operating Mechanism: Check the opening, closing, charging, and mechanical interlocking functions according to the applicable maintenance instructions.
8. Check Auxiliary Accessories: Inspect auxiliary contacts, shunt releases, undervoltage releases, and other installed accessories.
9. Verify Mounting Security: Confirm that the circuit breaker is correctly positioned and secured within the switchgear assembly.
10. Perform Electrical Testing: Carry out the required insulation, contact resistance, and protection function tests using approved procedures.
11. Conduct Operational Checks: Verify the mechanical and electrical operating functions before returning the equipment to service.
12. Document Maintenance Results: Record the circuit breaker configuration, protection settings, inspection findings, test results, and maintenance date.

Compatible System Components

Recommended Related Models

Key Advantages

• 2500 A rated current for high-capacity power distribution.
• H2 performance with 100 kA breaking capacity at 440 V AC.
• Three-pole configuration for three-phase distribution systems.
• Fixed mounting arrangement for compatible switchgear installations.
• Supports overload and short-circuit protection.
• Compatible with the MasterPact NW accessory and protection ecosystem.
• Suitable for industrial and commercial low-voltage distribution systems.

Technical FAQs

1. What does H2 mean in the MT25H2 circuit breaker configuration?

H2 identifies the circuit breaker’s performance level. For the NW25H2 configuration, it corresponds to a rated ultimate short-circuit breaking capacity of 100 kA at 440 V AC.

2. What is the rated current of the MT25H2?

The MasterPact NW25H2 configuration has a rated current of 2500 A at 40 °C. The actual operating conditions and switchgear installation must comply with the applicable equipment specifications.

3. Does the MT25H2 include a Micrologic protection unit?

The specified configuration is supplied without a control unit. A compatible protection unit must be selected according to the required protection functions and circuit breaker configuration.

4. What should be checked when replacing an MT25H2 circuit breaker?

Verify the MasterPact NW platform, 2500 A current rating, H2 breaking performance, three-pole configuration, fixed mounting arrangement, and control unit requirements. The existing switchgear connections and accessory configuration should also be checked before replacement.