Schneider Electric DC Molded Case Circuit Breakers

A Comprehensive Analysis of Schneider Electric DC Molded Case Circuit Breakers (DC MCCB)

Schneider Electric DC molded case circuit breakers are specially designed for DC systems, providing current protection ranging from 16A to 4000A and covering voltage classes from 500Vdc to 1500Vdc. They are suitable for various DC application scenarios such as photovoltaic systems, data centers, rail transit, and energy storage systems. The core product series include three main lines: ComPacT NSX DC (including PV-specific DC PV/EP variants), EasyPact CVS DC and MasterPacT NW DC, which integrate high-reliability breaking capacity, flexible wiring options and intelligent protection capabilities.

1. Overview of Core Product Series

1. Model Naming Convention Explanation (Taking NSX DC as an Example)

Taking the model C63S4TM500D as an example, the meaning of each segment is as follows:

Other common codes:

F/H: Breaking capacity classes (F: 36IL, H: 70IL)

PV: Photovoltaic-Specific

EP: 1500Vdc High-Voltage Version

NA: Isolating Switch Type

III. Key Technical Parameters and Performance

1. Rated Voltage and Breaking Capacity

Standard Type: 750Vdc, Icu = 36-100kA (depending on breaking capacity class)

PV Type: 1000Vdc, Icu = 50-100kA

High-Voltage Type: 1500Vdc, Icu = 50kA

High-Current Type: 900Vdc, Icu = 85kA (NW DC Series)

2. Trip Unit Types

Thermal-Magnetic Trip (TM-DC): Overload long-time delay (adjustable from 0.7-1In) + short-circuit instantaneous protection, suitable for general-purpose power distribution.

Electronic Trip (Micrologic DC): Four-stage protection including long-time delay, short-time delay, instantaneous protection and earth fault protection, with precise adjustability, suitable for critical loads.

3. Mounting and Wiring Methods

Mounting: Fixed/draw-out type, installed on 35mm DIN rail or front-panel mounting.

Cablaggio: Supports three DC-specific methods

Standard Wiring: Single-pole independent connection, suitable for ≤750Vdc.

Pole Series Connection: Enhances breaking capacity, suitable for high-voltage scenarios.

Pole Parallel Connection: Increases rated current, suitable for high-current scenarios.

Terminals: Compatible with copper/tinned copper cables of different wire gauges, with torque values varying by specification.

1. Core Functions and Advantages
2. DC Arc Extinguishing Technology

Double Rotary Contacts (NSX Series): Fast arc extinguishing, reduces arc energy, and improves breaking reliability.

Double-Break Arc Extinguishing (CVS Series): Enhances current-limiting capability and reduces thermal shock.

Dedicated Arc Chute: Adapted to the zero-crossing-free characteristic of DC current, improving arc extinguishing efficiency.

2. Protection Features

Overload Protection: Inverse time characteristic, matched with the thermal curves of cables/equipment.

Short-Circuit Protection: Instantaneous operation, with strong Icw short-time withstand capability.

Isolation Function: Complies with EN/IEC 60947-2, ensuring maintenance safety.

PV-Specific Protection: Reverse polarity protection, adapted to the characteristics of photovoltaic arrays.

3. Intelligent Features

Micrologic Trip Unit: Precise protection parameters, event logging, and communication functions (NW DC/high-end NSX models).

EcoStruxure Power Commission: Remote configuration, testing and maintenance.

Power Monitoring: Integrated measurement of parameters such as I/U/P/E/THD (high-end models).

1. Application Scenarios and Selection Key Points
2. Scenari applicativi tipici

2. Core Selection Steps
3. Determine System Parameters: Tensione nominale (Ue), corrente nominale (In), prospective short-circuit current (Isc).
4. Select Product Series: Choose NSX/CVS/NW series according to voltage class and budget.
5. Determine Breaking Capacity: Ensure Icu ≥ Isc, calculated based on the short-circuit current at the installation point.
6. Select Trip Unit Type: Thermal-magnetic trip for general loads, electronic trip for critical loads.
7. Pole Number and Wiring: 3P3D (three-phase DC) or 4P4D (including neutral wire), consider pole series connection for high-voltage scenarios.
8. Accessory Configuration: Contatti ausiliari, undervoltage release, communication modules, ecc.
9. Installation and Operation Precautions
10. Specifiche di cablaggio

DC systems must distinguish between positive and negative poles, reverse connection is strictly prohibited (except for PV-specific models).

Special insulation accessories must be used for pole series connection to ensure creepage distance.

Cable cross-section should be selected according to rated current and temperature rise requirements, with torque applied in accordance with manual specifications.

2. Operation and Maintenance

Mechanical and electrical tests must be performed before initial use.

Regularly inspect the arc chute, contact wear and wiring tightness.

Wait for capacitor discharge after power-off of DC systems before conducting maintenance.

3. Avvertenze di sicurezza

DC arcs are not easy to extinguish, switching isolating switches under load is strictly prohibited.

Insulated tools and protective equipment must be equipped for high-voltage DC systems.

Interchangeable use with AC circuit breakers is not allowed, even if parameters are similar.

VII. Series Comparison Overview

With four core advantages including full-series coverage, high-reliability arc extinguishing, flexible wiring and intelligent protection, Schneider Electric DC molded case circuit breakers have become the preferred solution for DC system protection. During selection, three key factors including voltage class, breaking capacity and trip unit type should be focused on, and the appropriate series should be selected according to application scenarios. It is recommended to refer to Schneider Electric’s official selection manual or consult technical support to ensure optimal protection effect and system compatibility.