Featured Guide
Latest by date
High Voltage
Category articles
Explore medium- and high-voltage switching duties, insulation, cable terminations and testing. Start with the switching-device overview, then compare equipment for your application.Switching devices · Breaker vs. contactor
-
MV Power-Factor-Correction Circuit Breakers: Selection, Switching Duty and Coordination Checks
A medium-voltage circuit breaker for a power-factor-correction capacitor bank cannot be selected from feeder current alone. The breaker must make, carry and interrupt a bank under conditions that…
-
Surge Arrester Selection for Transformer Protection: A Coordination Checklist
Selecting a surge arrester for a transformer begins with the terminal being protected, not with a product family. The reviewer must know the system voltage and earthing, the…
-
ANSI Circuit Breaker Ratings: How to Compare the Highest Numbers
The breaker with the largest number on its data sheet is not automatically the breaker with the highest usable ANSI rating. That statement is not a word game.…
-
Fixed vs. Withdrawable MV Switchgear: Maintenance, Floor Space and Interlocking
Choose a fixed functional unit when the approved isolation and maintenance plan can establish the required work boundary without moving the device, and the installation provides the access…
-
GIS Bay Maintenance: Isolation Boundaries and Restoration Checks
A gas-insulated switchgear (GIS) bay outage needs three reconciled boundaries: the primary electrical circuit, the protection/control interfaces and the gas compartments affected by the task. A bay name…
-
MV Transformer Feeder Cable Sizing: A 20/3.3 kV Calculation Workflow
An MV transformer feeder cannot be sized from transformer MVA and an ampacity table alone. First identify which winding the cable serves; then establish insulation duty, route-specific thermal…
-
MV Switchgear Commissioning: Evidence Required Before Energization
Medium-voltage (MV) switchgear is ready for initial energization when the installed assembly, its protection and control interfaces, and its restored operating configuration have traceable acceptance evidence. A passing…
-
MV Cable Insulation Selection: XLPE, TR-XLPE and EPR
Choose medium-voltage cable insulation by comparing complete cable constructions under the same service conditions. XLPE, tree-retardant XLPE and EPR identify material families; they do not independently establish voltage…
-
Aging Switchgear: When to Repair, Retrofit or Replace
Calendar age should trigger a review, not automatically decide replacement. Repair is defensible when the defect is localized and the retained assembly remains fit for its duty. Retrofit…
-
Medium-Voltage Circuit Breaker Ratings: A Specification Crosswalk
An MV circuit breaker is not adequately specified by “kV, A and kA.” Match each rated duty to the corresponding system condition: maximum operating voltage and insulation stress,…