The United Kingdom Atomic Energy Authority has a requirement to expand our Auxiliary Field Power Supplies with the possibility of a full upgrade and expansion. The existing system comprises of: Two modular (x4 Regatron LAB.TC modules each) single-quadrant Regatron rectifiers in two separate cubicles.415V, 3 x 60A input and 32kW output from each sub-module. Options under consideration are upgrading the system to newer modular supplies and expanding from two to four supplies OR the expansion of the system to include two different more modern supplies with the intention to upgrade incrementally over a longer period. The UKAEA seeks market engagement to help inform the process prior to tender.