S0 frame, 45 mm wide — panel fit constraints
The 3RT2028-1AL20-ZW96: That 45 mm width is the critical dimension for DIN-rail density — it occupies a single 45 mm module on the rail, so a 600 mm rail section holds 13 units with no gap. These are the minimum air gaps to maintain rated insulation — tighter spacing risks flashover between phases or to ground.
Wire termination — main and auxiliary contacts
The magnet coil uses screw-type terminals — no push-in or spring-cage option on this variant, so factor in screwdriver access during panel wiring.
Rated for 10 million mechanical operations typical — that's the contactor body itself, not the contacts under load. For a line running 10 cycles per hour, that's over 100 years of mechanical life; the electrical endurance under load is the real limit. Maximum switching frequency depends on duty class: 1000 operations per hour in AC-1 (resistive loads), 750 ops/h in AC-2, AC-3, and AC-3e (motor starting/running), and 250 ops/h in AC-4 (plugging, inching, reversing). Exceeding these rates shortens contact life — the arcing time of 4 to 16 ms per operation adds up fast at high cycle rates.
Auxiliary contact ratings — what they switch
At 400 V it's rated 3 A. These are the make/break capacities for the control circuit — don't assume the 10 A rating holds at higher voltages. Breaking capacity at 50 Hz is 0.25 A, at 60 Hz is 0.28 A — these are the maximum currents the auxiliary contacts can interrupt in an AC control circuit. For DC control, use the voltage-specific ratings above.