Fundamentals of mechatronics

A: Dropping the contactor removes mechanical motion, not stored or supplied electrical energy inside the cabinet, so shock risk stays. Restart risk is handled by the safety relay reset logic, not by the E‑stop itself. Winding temperature falls once power is removed, so overheating isn't the concern here. Encoder reference loss is a functional issue, not a safety hazard addressed by an E‑stop.

A: A 12‑bit converter has 2^12 codes, so the step is full‑scale divided by 4096. The 11‑bit argument mixes ENOB with ideal resolution. Dividing by 4000 is a decimal shortcut that looks tidy but shifts every threshold. Halving the value comes from double‑counting endpoints, which doesn't match how ADC codes are defined.

A: Dashed lines on P&IDs typically separate instrumentation signals from process piping. Redundant tubing would still be shown as solid process lines. Wireless links are called out explicitly with notes or symbols. Temporary hookups belong in commissioning sketches, not the issued P&ID.

A: Dissimilar metals plus moisture set up a galvanic cell, and aluminum sits anodic to steel, so it sacrifices locally. Steel will rust, but that doesn't explain aluminum loss at the joint. Stress corrosion needs tensile stress and a specific environment, which isn't stated. Chloride‑driven crevice corrosion needs salts, not just humidity.

A: During decel the motor pumps energy back into the DC bus, and without enough dissipation the drive trips on overcurrent or overvoltage. Encoder resolution affects smoothness, not energy flow. Aging capacitors raise ripple, but the symptom would show under load both ways. Gearbox friction raises current on accel and steady motion, not just on stopping.

A: For DC, power is simply V times I. Halving it by invoking RMS mixes AC thinking into a DC case. Torque constants relate electrical to mechanical domains, not raw input power. Doubling for rails misunderstands single‑supply systems.

A: Light curtains interrupt control power, not stored potential energy, so gravity hazards need mechanical brakes or counterbalances. Reach‑in is exactly what the curtain addresses. Fatigue is a durability issue, not an immediate hazard. Misalignment degrades availability but doesn't define the residual hazard itself.

A: A tag mismatch can hide cross‑wiring or wrong range devices, so you stop and formally reconcile under MOC. Assuming a typo is how latent faults escape. Renaming only one artifact breaks traceability. Updating documents after the fact flips the safety lifecycle on its head.

A: The undamped natural frequency comes from the square root of stiffness over mass, then converted from rad/s to Hz by 2π, landing near 10 Hz. Skipping the square root inflates the result. Damping level doesn't set the natural frequency here. Judging by feel instead of math is how resonances sneak into service.