Criticality of powering failure of the main bend circuits in the FCC-ee at the Z-pole energy

The electron-positron Future Circular Collider (FCCee) will have a first phase of operation at the Z-pole energy of 45.6 GeV. To reach the target luminosity, a total of 11200 bunches with $2.14 \times 10^{11}$ charges will be used, accounting for a stored energy of 17.5 MJ per beam. Given the small beam emittances, the beam energy density in turn reaches extremely high values. The potential to induce severe damage to the accelerator components must be carefully evaluated for different failure scenarii. The effects of a powering failure of one of the main dipole circuits are described and discussed. The time-dependent effects are simulated with the XSuite tracking code. The results, expressed in term of orbit shifts, optics changes and particle losses, show that this failure is highly critical. The fastest scenario in which the beam experiences a horizontal orbit excursion of 11$\sigma$ in three turns is analysed in detail. Interlocking and mitigation strategies have been evaluated and are discussed.