Microwave ovens contain a very powerful high voltage transformer (MOT = microwave oven transformer), see photo. A typical output voltage is 2kVeff, at around 1000W power. This is equivalent to about 0.5Aeff output current @ 2kVeff output voltage. The short-circuit current is even higher.
Microwave/oven High Voltage Transformer 800W
HIGH VOLTAGE 220v, 60hz