Not_a_boffin,
Good morning to you.
The following is a quick flowchart of the EMALS system.
Ship Power à Energy Storage (Alternator) à Power Conversion/ conditioning (Cycloconverter) à Launch Rail’s Linear Motor
The energy-storage system uses spinning rotors of a disk alternator as a flywheel to kinetically store energy it draws from the ship’s power system.
Each of the four alternators will store more than 100 MJ, spinning at about 6400 rpm. Ship electric power drives the rotors to their target rpm.
When launching an aircraft the power-correction subsystem uses the same coils that drive the rotor to draw off their power as the rotor shifts from its motor mode to its alternator mode. Each rotor outputs approximately 81.6 MW at maximum speed. Even at an anticipated efficiency of about 90%, there is about 127 kW of heat generated that the system needs to remove from the alternator every 45 seconds, and this is done via several heat-transfer subsystems.
The average power required by EMALS is 6.35 MVA
In the 3 seconds it takes to launch an aircraft, the amount of power used could power 12,000 homes
The fact that you are cycling through taking power from a supply always causes shock loading/ unloading. To launch the two F-18s that the UK will eventually be able to afford ( J ) is not too bad compared to a US Carrier launching multiple aircraft at a fast rate.
As long as the generator, bus bars and switchgear are able to take this sustained loading and unloading then no problems.