A stationary compressor motor needs a strong push to start turning against the pressure in the system. For a fraction of a second up to a couple of seconds, it draws a current several times its running current. Once it reaches speed, the current drops to the normal running value shown on the rating plate.
This surge matters for wiring and backup power. Thin extension leads, loose socket contacts and long cable runs cause the voltage at the compressor to dip during the start, which can stop it from starting at all. Inverters and small generators that comfortably supply the running load may trip when the compressor tries to start. Several cabinets starting together after a power cut add up to a large combined surge.
Inverter compressors start softly and draw far less inrush current, which is one reason they pair well with battery backup and generators. For fixed-speed units, start components such as a start capacitor help the motor start quickly, reducing the time spent at high current.