Selection Process: A Five-Step Approach
Selecting a box-type substation involves five steps: capacity calculation, structural configuration, high/low-voltage setup, environmental adaptability, and manufacturer proposal evaluation.
Industry experts advise following this workflow—capacity calculation (load statistics + margin), structural configuration (European/American/Chinese styles), high/low-voltage setup (transformer + HV switchgear + LV switchgear), environmental adaptability (outdoor use/dust protection/temperature rise), and manufacturer proposals (comparing options)—with capacity and structure being the critical factors.
The Five-Step Process
- Capacity Calculation: Load statistics (demand factor) + margin (20%–30%) to determine transformer capacity (e.g., 500kVA);
- Structural Configuration: European style (fully enclosed/safe), American style (compact/economical), or Chinese style (hybrid of European and American);
select based on the application scenario; - High/Low-Voltage Setup: High voltage (ring main unit/load break switch) + transformer + low voltage (feeders/reactive power compensation); ensure configuration compatibility;
- Environmental Adaptability: Outdoor environment (IP rating/dust & moisture protection) and temperature rise (ventilation/heat dissipation);
determine based on the environment; - Manufacturer Proposals: Compare technical proposals (enclosure/layout) and select the best option.
Key Selection Points
First, allow for capacity margin.
Include a margin for load growth (20%–30%) to avoid needing to replace the transformer later due to capacity expansion.
Second, choose the structure based on the application scenario. Select between European style (safety-focused) and American style (cost-effective) based on the site conditions and budget.
Third, verify test results.
Ensure compliance regarding type tests (GB/T 17467) and specific verifications (temperature rise/protection).
Fourth, evaluate manufacturer proposals.
Compare options from multiple vendors (layout/price) and select the best fit.
Pitfalls to Avoid
First, “insufficient capacity.”
Avoid transformer undersizing (overload) by building in a capacity margin.
Second, “excessive temperature rise.”
Prevent overheating within the enclosure (which leads to derating or failure) through proper ventilation design.
Third, “inadequate protection.”
Avoid insufficient outdoor protection (ingress of water or dust) by confirming the appropriate IP rating.
Trends and Recommendations
Box-type substations are trending toward “prefabrication,” including prefabricated modular substations (for rapid deployment) and units tailored for new energy applications (PV/energy storage).
For those selecting equipment, the recommendation is to “allow for capacity margins, match the structure to the application environment, and verify test results.”
Proper selection ensures reliable power supply.
