Standard diagram of the center of gravity of the secondary distribution box

The center of gravity of a secondary distribution box is typically marked at the geometric center or calculated point where the box's weight is balanced, and it is represented in diagrams to ensure safe handling and transport.

Principles of Center of Gravity Marking

The center of gravity (CoG) represents the point where the weight of the box can be considered concentrated. For secondary distribution boxes, this is crucial for safe lifting, stacking, and transportation. The CoG should be indicated on at least two adjoining walls, and ideally on all four sides, using the standard symbol defined in DIN EN ISO 780 or local regulations ( ). This ensures handlers can quickly identify the balance point.

Load Distribution and Diagram Representation

A load distribution diagram shows the allowable position of the CoG relative to the box dimensions. For secondary distribution boxes:

• The CoG is usually near the geometric center if the internal components are evenly distributed ( ).
• If the box contains unevenly distributed equipment, the CoG must be calculated based on the weight and position of each component.
• The diagram typically includes:
  • Top view showing the CoG along the length and width.
  • Side view showing the CoG height from the base.
  • Allowable eccentricity limits, often ±5–10% of the box dimensions, to account for minor weight shifts ( ).

Practical Guidelines

1. Marking: Use the CoG symbol on visible sides of the box to guide lifting and handling.
2. Calculation: Determine the CoG using the formula: $$X_{CoG}=\frac{\sum (x_i·m_i)}{\sum m_i},Y_{CoG}=\frac{\sum (y_i·m_i)}{\sum m_i},Z_{CoG}=\frac{\sum (z_i·m_i)}{\sum m_i}$$ where $x_i,y_i,z_i$ are coordinates of each component and $m_i$ is its mass ( ).
3. Safety: Ensure the CoG is within the central area of the box to prevent tipping during lifting or transport.
4. Diagram Use: The diagram can be included in technical documentation or on the box itself to guide operators and automated handling systems. By following these principles, a standard CoG diagram for a secondary distribution box can be created, showing the central point of balance and any allowable deviations, ensuring safe handling and compliance with international standards ( ).