In rural power grid renovation and new construction projects, scientifically designing lighting electrical ready boards is the core link to ensure electrical safety and optimize line layout. The following recommends a set of load calculation and line planning methods based on online tools, combined with practical cases and regulatory requirements, to provide practical technical solutions for rural electricians.

1、 Load calculation tool: Accurately match transformer capacity

Need coefficient method for online calculation

By using an online calculator, input the number of users, single household power, and load factor to automatically generate the total load value. For example, a village plans 500 households with an average power of 1.5 kW per household, a load factor of 0.7, and a total load of:

P=500×1.5×0.7=525kW

It is recommended to choose a 1000kVA transformer to reserve space for future load growth.

Single phase and three-phase load balance verification

If the proportion of single-phase load exceeds 15%, it needs to be converted into equivalent three-phase load. For example, the total capacity of a single-phase load in a certain electrical ready board is 10kW, and the three-phase load is 50kW. Since 10/50=20%>15%, the equivalent three-phase load needs to be calculated based on three times the maximum single-phase load

The total load is 15kW+50kW=65kW, multiplied by a demand factor of 0.8, resulting in a calculated load of 52kW.

2、 Route planning tool: optimizing wire cross-section and path

Selection of Voltage Loss Method

Using an online wire cross-section calculator (such as the "Electrical Engineer Assistant"), input the line length, load power, and allowable voltage drop (usually ≤ 5%) to automatically recommend wire models.

Geographic Information System (GIS) assisted path planning

Through the "Rural Power Grid Planning GIS Platform", village topographic maps, building distribution, and existing line data are imported to automatically generate the shortest path plan and avoid sensitive areas such as farmland and water sources. For example, a village plans to build a new 380V line, and GIS tools recommend installing it along the village road, reducing the total length by 15% and construction costs by about 12%.

3、 Design Verification and Safety Standards

Short circuit current verification

Use online short-circuit calculation tools (such as "ETAP Cloud") to input transformer parameters, line impedance, and load type, and verify whether the breaking capacity of the circuit breaker meets the requirements. For example, if the short-circuit current at the outlet of a 1000kVA transformer is 16.5kA, a circuit breaker with a rated breaking capacity of ≥ 20kA should be selected.

Reactive power compensation configuration

According to the Technical Regulations for Low Voltage Power in Rural Areas, the power factor of lighting loads should be ≥ 0.9.

4、 Case application: Renovation of lighting electrical ready board in a village

The original electrical ready board capacity in a certain village was 200kVA, with a long-term load rate exceeding 80% and severe aging of the lines. Redesign using the above tools:

Load calculation: The total load is 525kW and needs to be replaced with a 630kVA transformer;

Line renovation: Replace the original LGJ-50 type with LGJ-150 type wires, reducing the voltage drop from 8% to 3%;

Security upgrade: Install a leakage protector, with a single-phase grounding fault action time of ≤ 0.2s.

After the renovation, the line loss was reduced by 40% and the annual power outage time was reduced by 120 hours.

5、 Tool recommendation

Load Calculation: Electrician's Home Load Calculator SKM Power Tools；

Line planning: AutoCAD Electrical, rural power grid planning GIS platform;

Security verification: ETAP Cloud, Nanrui Jibao short-circuit calculation software.

By combining online tools and standards, the design of rural lighting electrical ready boards can achieve "precise calculation, intelligent planning, safety and reliability", providing power guarantee for rural revitalization.