Electrical Engineering Articles & Guides
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Medium-Voltage Fuse Ratings Explained: Voltage, Current and Breaking Range
An MV fuse link has several different ratings, not one “size.” Rated voltage addresses the application voltage; rated current relates to carrying normal current under specified conditions; breaking-current…
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How Overcurrent Protection Changes Arc-Flash Incident Energy
The protective device changes an arc-flash estimate primarily through the arcing current it sees and how long it takes to clear that current. A current-limiting fuse, instantaneous breaker,…
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MCCB Selection for Automatic Power-Factor-Correction Panels
Select the incoming molded-case circuit breaker (MCCB) for an automatic power-factor-correction (APFC) panel from the bank’s maximum operating current, installation fault level, protection/coordination requirements and verified assembly design.…
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Control Transformer Sizing for Contactor Pickup and Holding
Do not size a contactor control transformer from coil holding VA alone. Build at least two load cases: the largest credible simultaneous pickup demand, and the steady sealed/holding…
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Medium-Voltage Circuit Breaker Operating Sequence Explained
An operating sequence describes a breaker’s assigned ability to perform specified open and close–open operations at stated intervals; it is not an instruction to reclose every faulted feeder.…
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Low-Voltage Circuit Breaker Selection for Selective Coordination
Selectivity means a downstream fault is cleared by the protective device nearest that fault while an upstream device remains closed, within a defined range of fault currents. To…
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Busbar vs. Terminal-Block-and-Cable Wiring in Control Panels
An engineered busbar system is often attractive when a low-voltage panel distributes substantial current to repeated devices in a compact, stable layout. Discrete cable and terminal blocks usually…
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Transformer Abnormal Noise: Five Sound Patterns and Safe Next Steps
A power transformer normally produces some audible sound. The useful warning is a new, louder, irregular, or relocated sound compared with that unit’s baseline under comparable operating conditions.…
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GFCI vs. AFCI: What Each Device Protects Against
A ground-fault circuit interrupter (GFCI) and an arc-fault circuit interrupter (AFCI) respond to different hazards. A GFCI compares current leaving and returning on the intended circuit conductors and…
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LV Cable Terminations: Components, Methods and Failure Prevention
A reliable low-voltage cable termination is a controlled electrical and mechanical interface. The connector must match the conductor material, size, strand class, temperature rating, and equipment terminal; preparation…