What the frame size and mounting tell you about panel fit
The 3RT2018-2AN22: The body measures 45 mm wide by 70 mm high by 73 mm deep, so it occupies about the same footprint as a four-module MCB.
Duty-cycle limits and switching frequency
The maximum switching rate depends on the duty class: 1,000 operations per hour in AC-1 (resistive loads), 750 ops/h in AC-2 and AC-3 (slip-ring and squirrel-cage motors), and 250 ops/h in AC-4 (plugging/inching). Exceeding these limits accelerates contact wear and reduces the 30 million-cycle mechanical life. These numbers matter when coordinating with upstream overcurrent devices — the contactor clears the arc fast enough to avoid nuisance fuse blowing on moderate overloads.
Auxiliary contact ratings across the voltage range
These are the continuous thermal current ratings at the respective voltages — use them to size the control circuit load without an external aux block. At 400 V the auxiliary contact is rated 3 A, which covers most PLC output card loads and small relay coils in the same panel.
Wire termination and environmental limits
This eliminates screw-torque checks during replacement — a time saver on line-down swaps.