Router has died. Need Advise Please.

[EddyCurrent]

I would have a look at various manuals for major inverter manufacturers to see what they say, these can be viewed or downloaded as pdf's.
For example an ABB manual says for 1.5kW the input cable should be 2.5mm^2, motor cable should be 1.5mm^2

"Motor cables
(recommended for input cables also)
Symmetrical shielded cable: three phase conductors, a concentric or otherwise
symmetrically constructed PE conductor and a shield

Note:
A separate PE conductor is required if the conductivity of the cable shield is not
sufficient for the purpose"

So in terms of CY cable that's 3 core cable for the motor using the outer as the earth conductor and screen, this should be connected at both ends to obviously act as an earth conductor and to give 360 degree connections for EMC shielding (that's what CY glands are for). If the CY screen is of less cross sectional area than the inner conductors then another core should be used for the earth, i.e. 4 core cable or a separate earth cable run on the outside.

The supply cable could be 4 core armoured.

Before anyone jumps on the well known idea about connecting screens at one end only I suggest you do a search for EMC cable screening first.