Mechatronics

A: B feels slow and old-school, but it catches wiring damage before silicon gets stressed. A tempts controls folks because software is visible early, yet powering logic without knowing insulation is asking for a blown drive. C is what everyone wants to do, but motion before electrical integrity is backwards. D is a real safety check, just not before you know the motor and cables won’t leak current into the drive on first power.

A: A ties directly to the risk: loss of torque must survive one fault. B sounds plausible if you mix in SELV rules, but ISO 13849 doesn’t draw voltage lines like that. C flips the logic; higher categories usually add, not remove, diagnostic expectations. D imports assumptions from old relay-based machines and doesn’t exist in the standard’s intent.

A: Start with distance: 0.5 m/s over 2,000 h at 30% gives 0.5×720,000 s ≈ 360 km. At 10 mm per rev, that’s 100 rev/m, so ~3.6×10^7 rev. A drops a zero by missing either duty or seconds. C double-counts speed and time. D feels conservative but throws away two orders of magnitude by misusing downtime.

A: A matches physics: more inertia hits the accel phase, not cruise. B sounds like classic control talk, but integral windup won’t fix torque limits. C treats a thermal symptom that hasn’t happened yet. D blames sensors when the plant changed.