Three Phase Power. Phase Currents to Power and KVA calculations
a)
The KVA, or the apparent power is the product of the current and the voltage. For three-phase systems you can imagine it like a superposition. You have three currents comming in(or out) and each is at 240V(phase to ground). So the total apparent power would be:
$$S=U_{phase}I_1+U_{phase}I_2+U_{phase}I_3$$
Where \$U_{phase}=240V. \$

b)
The power is calculated as:
$$P=S\cos\varphi$$
Where the phase difference between voltage and current is the angle \$\varphi\$, and  \$\cos\varphi\$ is called power factor.

It is not possible to calculate the power \$P\$ (in kW) from the given data. See what other readings you can get.

There are far more details to it, now we are just looking at the first harmonic. You can look into the other stuff when you get this done.