The internal compartmentalization of low voltage panels is an essential factor to ensuresafety, reliability, and operational continuityin industrial electrical systems.
Concept of Compartmentalization
Compartmentalized panels are designed to physically separate:
The separation forms defined byIEC 61439-2 (NBR IEC 61439-2)establish clear criteria on how internal elements should be segregated, directly impacting the panel's performance under normal and fault conditions.
Busbars
Functional units (circuit breakers, starters, inverters)
Connection terminals
This separation can be achieved by metallic or insulating barriers, creating increasing levels of internal protection.
Regulatory Basis – IEC 61439
The IEC 61439 standard defines the requirements for low voltage switchgear assemblies, including:
Thermal tests
Short-circuit withstand strength
Degree of protection (IP)
Performance verification
Forms of internal separation
The classification of forms considers three main points:
Separation of busbars
Separation of functional units
Separation of terminals
Form 2A and 2B
Form 2 represents the first level of real compartmentalization within the panel.
In Form 2A:
Busbars are separated from functional units.
Terminals remain in the same compartment as the units
In Form 2B:
Busbars are separated
Terminals are separated from the busbars
Terminals still share space with the functional unit
This level offers basic protection against contact with busbars, but still allows interaction between circuits.
Typical applications include:
Building distribution boards
Commercial systems
Low criticality installations
Form 3B
Form 3 raises the level of segregation by also separating the functional units from each other.
In Form 3B:
Busbars are separated
Functional units are separated from each other
Terminals are separated from the functional units
This level significantly reduces the propagation of internal failures and improves safety during maintenance.
Typical applications:
Motor Control Centers (MCC)
Medium-sized industries
Systems with a need for higher availability
Form 4B
Form 4 represents the maximum level of compartmentalization defined by the standard.
In Form 4B:
Busbars are completely separated
Functional units are completely segregated
Terminals are individualized by functional unit
Each circuit operates independently within the panel.
This ensures:
Maximum operational safety
High reliability
Minimal interference between circuits
Typical applications:
Data centers
Mining
Oil and gas
Critical infrastructures
Technical Comparison
Form 2 → basic protection, less segregation
Form 3 → greater fault control and better maintenance
Form 4 → complete isolation and maximum continuity
The main evolution between the forms is in thereduction of the risk of fault propagation and increased system availability.
Importance in Engineering
The correct choice of compartmentalization directly impacts:
Safety
Reduction of internal arc
Operator protection
Operational continuity
Prevents total shutdowns
Isolates faults in specific circuits
Maintenance
Allows for safer interventions
Reduces downtime
Reliability
Minimizes cross-faults
Improves system performance
Selection Criteria
The definition of the form should consider:
System short-circuit level
Criticality of operation
Need for maintenance with the system energized
Customer requirements or specific standards
Environmental conditions (e.g., altitude, temperature)
Application in CWF Systems
In the projects of CWF Mechatronic Systems, compartmentalization is treated as a critical engineering element.
Solutions such as are adopted:
Form 3B and 4B for industrial applications
Modular systems and removable drawers
Studies based on IEC 61439 and IEC 61641
Integration with high-performance equipment
This level of engineering ensures:
High reliability
Operational safety
Reduction of unavailability
Conclusion
The compartmentalization of electrical panels is a decisive factor in the quality of the system.
The correct application of forms 2A, 2B, 3B, and 4B allows for a significant increase in the level of:
Safety
Continuity
Operational efficiency
In modern industrial projects, the trend is clear:
Forms 3B and 4B are the standard for critical and high-performance systems.