14AN-4 Distribution Cabinet Load Calculation

Because the three-phase load is unbalanced, it cannot be calculated based on the three-phase load in a general way. First, calculate the three main lines:

WLM1:L126+26=52,L2=L3=26

WLM2:L1=L2=24,L3=24+24=48

WLM3:L1=L2=L3=24

Calculate WLM4~WLM5 again

Pe=10+10=20

Kx=1

Pjs=20

Total: L1=52+24+24=100

L2=26+24+24=74

L3=26+48+24=98

Equivalent to three-phase load by taking three times the maximum phase:

Pe=100*3=300KW

Kx=0.55 (single phase 16 households)

Pjs=165KW

Total of the entire cabinet:

Pjs=165+20=185

Kx=185/320=0.58

cosφ=0.9

ljs=311A

Key point: Try to maintain three-phase balance as much as possible

Load during firefighting:

Pe=240KW

12 fans (33+33+24) * 0.7=63

2 elevators (18+18) * 1=36

4 water pumps (7.5 * 4) * 0.9=27

Emergency lighting: 15+15+3=33

Pjs=63+36+27+33=159Kw

Normal load:

Pe=240

6 fans, 24 * 0.8=19.2

4 elevators (18+18+18+18) * 0.8=57.6

Weak current room and drainage pump 15 * 1=15

Emergency lighting (15+15+3) * 0.5=16.5

Pjs=19.2+57.6+15+16.5=93.3

Summary

1. Single phase loads should be evenly distributed among the three phases as much as possible. When unbalanced, three times the maximum phase load should be taken as the equivalent three-phase load.

When the total calculated capacity of single-phase load is less than 15% of the total calculated capacity of three-phase symmetrical load within the calculation range, all calculations should be based on three-phase symmetrical load; When it exceeds 15%, the single-phase load should be converted to an equivalent three-phase load and then added to the three-phase load.

3. The load calculation of the distribution cabinet should include backup loads. Because the end effector is automatically switched.

4. Consider different usage times and purposes to meet the maximum demand.

*Reprinted from the Electrical United Front.