SIRIUS Size S00 power contactor
The 3RT2018-4AK61: This is a standard industrial control voltage in many regions; the dual-frequency rating means the same coil works on 50 Hz or 60 Hz supply without a change.
Physical dimensions are 73 mm deep, 45 mm wide, and 58 mm tall. These clearances are for heat dissipation and arc flash containment — respect them in the panel layout to avoid derating or arc-over between adjacent devices.
Maximum switching rates: 1,000 operations per hour for AC-1 (resistive) loads, 750 ops/h for AC-2 and AC-3 (motor) duty, and 250 ops/h for AC-4 (plugging/inching) duty. The AC-3e rating also caps at 750 ops/h. These limits are set by thermal rise in the contact tips during arcing — exceeding them shortens contact life or causes welding. This is the contactor mechanism endurance without electrical load; actual electrical life depends on the switched current and load type, and will be lower under heavy AC-4 duty.
Auxiliary contact ratings and arcing
The contactor includes an auxiliary switch block. These are the make/break capacities for the auxiliary circuit — use them to size the control transformer and fuse protection for the PLC or relay inputs. Arcing time is 4 to 15 ms at AC, with a typical range of 10 to 15 ms. This is the duration the arc sustains between opening contacts — relevant for coordination with upstream protection devices and for estimating contact erosion per switching cycle.
Temperature range and storage
Storage temperature range is -55 °C to +80 °C. The wide storage range allows the contactor to sit in a spare-parts bin in unconditioned warehouses; the operating range covers most industrial environments but note that the coil pull-in voltage and contact ratings may need derating at the temperature extremes.