The basic equation I've been using to calculate the amount of Amperage required to achieve a particular power output using 3-phase electricity is:
Amp. = Watts / (√3 × PF × Voltage)
where PF = Power Factor, which in my case is assumed to be 1.0 (heating elements). For example, to run 18000 on 230 volt 3-phase electricity would require 45.2~ amps.
Amp. = 18000 / (1.732 x 1.0 x 230) = 45.2 amps
However, if the voltage is High Leg Delta, even though the 3 phases are each measuring approx. 230 volts, but 2 of the legs are much lower than the third, should the same equation be used to anticipate required amperage?
BONUS QUESTION: In real-world applications, multimeters are obviously reading different amperages for each live wire, but on paper, the total amperage may in fact be found using the aforementioned equation. This poses a particularly difficult challenge when using Thermal Overload Relays that are used to set the overload threshold. We are seeing that for people using High Leg Delta, the setting isn't actually factoring in individual legs, but the overall amperage as the relay isn't being tripped when the legs excede the setting. The side effect of permitting this strange high amperage, but not really, to pass is that other equipment sensitive to amperage is being damaged. My inclination is to overcompensate, but figured this must something that has been addressed.
Any guidance is appreciated.