How are these values calculated in the distribution box?

Pe is the capacity of the equipment, which is generally obtained by adding the nameplate capacity of all the equipment

Ks is the need coefficient, which is the ratio of the active power (i.e., the calculated load of Pjs) required by the power-using equipment at maximum load to the capacity of the equipment, Pe

Pjs is the calculated load, which is calculated by the statistical calculation of the load

Pjs=Pe x Ks

Ijs is the calculated current, Ijs = Pjs / (1.732xUexCosφ), where Ue refers to the rated voltage, Ue = 380V (three-phase electricity)

Cosφ is the value of the power factor, the general value of this value can be based on the nature of the load, look up the table to find out, you can also refer to the nameplate of the equipment