The engineering glossary is a curated collection of technical terms, acronyms, abbreviations, and definitions used across engineering disciplines. Whether you are new to a field or need a quick refresher on a specific term, this resource provides clear, concise explanations.

## Electrical Engineering Terms **Power Factor (PF):** Ratio of real power to apparent power in an AC circuit. PF=cosθ where θ is the phase angle between voltage and current. Values range from 0 to 1. Low PF indicates reactive loads. **Short Circuit Current:** The current that flows when a fault occurs in an electrical system. Calculated using IEC 60909 or IEEE 141 methods. **Arc Flash:** An electrical explosion caused by a phase-to-phase or phase-to-ground fault. Energy released measured in cal/cm². **Protection Coordination:** Selection and setting of protective devices (relays, breakers, fuses) to isolate faults with minimum disruption. ## Civil & Structural Terms **Moment of Inertia (I):** Geometric property representing a cross-section's resistance to bending. Units: mm⁴ or in⁴. **Modulus of Elasticity (E):** Material stiffness — ratio of stress to strain within elastic range. Steel E ≈ 200 GPa, Concrete E ≈ 30 GPa. **Factor of Safety (FoS):** Ratio of ultimate strength to allowable stress. Typical values: 1.5-3.0 for static loads, 2.0-4.0 for dynamic loads. **Creep:** Time-dependent deformation under sustained stress. Significant in concrete, plastics, and metals at high temperatures. ## Mechanical & Piping Terms **Allowable Stress:** Maximum stress permitted in a component based on code rules. Typically a fraction of yield or ultimate strength. **MAWP (Maximum Allowable Working Pressure):** Maximum pressure a vessel or pipe may be operated at per code rules. **NPSH (Net Positive Suction Head):** Available suction head minus vapor pressure head. Critical for pump cavitation prevention. **Thermal Expansion (ΔL):** Dimensional change due to temperature. ΔL = α × L₀ × ΔT. Steel: α=1.2×10⁻⁵/°C. ## Process Terms **P&ID (Piping and Instrumentation Diagram):** Schematic showing process equipment, piping, instruments, and control loops. **HAZOP (Hazard and Operability Study):** Structured risk assessment methodology examining process deviations. **LOPA (Layer of Protection Analysis):** Semi-quantitative risk assessment evaluating independent protection layers.