The considerations to use soft start AC controllers in nuclear application

Motors larger than 200 HP shall be fed from 4.16 kV or 2.4 kV fused starters. In CANDU reactors all large pumps motors are supplied directly from the 13.8 kV, 6.3 kV or 4.16 kV AC system. In the MAPLE reactors, the Primary Coolant System pumps are supplied directly from the 2.4 kV AC system. Starting and stopping a pump may be easy, but the consequences may not always be ones we wanted. It can result in high start current that require large cables and fuses, or hydraulic shocks known as 'water hammer' can cause stress and damage to pipes, valves, gaskets and seals. If the nuclear plant installs soft starters, the result will be pump protection, which provides start and stop control, preventing both water hammer and expensive high start currents. (author)