Tech Topics
Medium-Voltage TechTopics
Medium-voltage TechTopics is a series of papers that discuss issues of interest to users or specifiers of medium-voltage electrical equipment, including:
- 5 - 15 kV arc-resistant, metal-clad switchgear (GM-SG-AR and NXAIR P)
- 5 - 38 kV non-arc-resistant, metal-clad switchgear (GM, GM-SG and GM38)
- 5 - 38 kV arc-resistant, gas-insulated switchgear (8DA10 and 8DB10)
- 5 - 27.6 kV metal-enclosed, load-interrupter switchgear (SIMOSEC)
- 2.3 - 15 kV motor controllers (Series 81000™, SIMOVAC and SIMOVAC-AR)
- 15.5 - 38 kV outdoor vacuum circuit breakers (SDV6 and SDV7)
- 5 - 38 kV retrofit and replacement circuit breakers.
Topics discussed in medium-voltage TechTopics will include application, selection and discussion of the applicable standards for these products. Medium-voltage TechTopics issues will be added to address recurring questions.
TechTopics No. 12, 40, 49, and 51 are reserved.
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Unless otherwise specified, the individual TechTopics pdf sizes are less than 500 kB.
- Entire TechTopics Catalog (25+ MB)
- No. 01 - Surge limiter application recommendations for metal-clad switchgear up to 15 kV
- No. 02 - Loss of vacuum
- No. 03 - Vacuum vs. SF6
- No. 04 - kA rated circuit breakers and switchgear
- No. 05 - Reclosing applications - minimum reclosing time
- No. 06 - Three-cycle versus five-cycle interrupting time
- No. 07 - Current transformers - Use of 600 V CT's in metal-clad switchgear
- No. 08 - Heat generation estimation for type GM switchgear (up to 15 kV)
- No. 09 - Heat generation estimation for type GM38 switchgear (up to 38 kV)
- No. 10 - Heat generation estimation for Series 81000™ controllers
- No. 11 - Fast bus transfer times for type GMI circuit breakers
- No. 13 - Use of latched contactors to switch transformers
- No. 14 - X-radiation emissions by vacuum interrupters
- No. 15 - Expected life of electrical equipment
- No. 16 - Bus joint fundamentals
- No. 17 - Main bus continuous current ratings
- No. 18 - Bus joint and primary disconnect plating
- No. 19 - Bus joint current density
- No. 20 - Power factor correction capacitor - sizing for motors
- No. 21 - "Bus bracing" in metal-clad switchgear
- No. 22 - "Bus bracing" in metal-enclosed switchgear
- No. 23 - Circuit breaker ratings - type GMI circuit breakers
- No. 24 - Checking integrity of vacuum interrupters
- No. 25 - Shunt reactor switching applications
- No. 26 - Ground bus ratings
- No. 27 - Standards for medium-voltage metal-clad switchgear
- No. 28 - Standards for outdoor high-voltage circuit breakers
- No. 29 - Derating factors for reclosing service
- No. 30 - Altitude correction factors
- No. 31 - Solar radiation correction factors
- No. 32 - Capacitor switching applications
- No. 33 - Clearance requirements in switchgear and control equipment
- No. 34 - Three-cycle vs. five-cycle interrupting time - type 3AK1 circuit breakers
- No. 35 - Transient recovery voltage
- No. 36 - Early "b" contacts
- No. 37 - Low current switching capabilities
- No. 38 - Harmonic filter applications
- No. 39 - Heat generation estimation for type NXAIR P switchgear (up to 15 kV)
- No. 41 - Circuit breakers or switches - application considerations
- No. 42 - Circuit breakers or vacuum contactors - application considerations
- No. 43 - Interposing relay requirements
- No. 44 - Anatomy of a short-circuit
- No. 45 - Accuracy of current transformers (CTs) used in medium-voltage control equipment
- No. 46 - Selection of current transformer (CT) ratio in medium-voltage control
- No. 47 - 7.2 kV equipment basic insulation levels (BIL)
- No. 48 - Fan-cooling control circuit for forced-air cooled circuit breakers
- No. 50 - Ground sensor current transformer cable routing
- No. 52 - Insulation of switchgear terminations
- No. 53 - Use of SF6 gas in medium-voltage switchgear
- No. 54 - Interrupter switch technology comparison - type SIMOSEC SF6 switch - conventional air switches
- No. 55 - Capacitor trip devices
- No. 56 - Switchgear outdoor enclosure type - Why isn't it NEMA 3?
- No. 57 - Arc flash hazard labels
- No. 58 - What is the difference between E-rated and R-rated current-limiting fuses?
- No. 59 - Control power sources for switchgear
- No. 60 - Use of cable for connections in medium-voltage switchgear
- No. 61 - Circuit breaker "standard duty cycle"
- No. 62 - A bit of history on circuit breaker standards
- No. 63 - Recovery of SF6 gas from type SIMOSEC switches at end-of-life condition
- No. 64 - NFPA 70E - Changes in 2012 edition
- No. 65 - Arc-furnace switching applications
- No. 66 - Clearances
- No. 67 - %dc component
- No. 68 - Heat generation estimation for historic switchgear type D (to 4.76 kV) and type F (to 15 kV) with air magnetic circuit breakers
- No. 69 - Fast bus transfer times for type GMSG circuit breakers
- No. 70 - Arc-resistant switchgear accessibility types
- No. 71 - Generator circuit breakers
- No. 72 - Generator circuit breaker applications - delayed current zeroes
- No. 73 - Generator circuit breaker applications - transient recovery voltage
- No. 74 - Heat generation estimation for type GM-SG or GM-SG-AR switchgear (up to 15 kV)
- No. 75 - Ferroresonance in ungrounded systems with voltage transformers connected line-to-ground
- No. 76 - Heat generation estimation for SIMOSEC load-interrupter switchgear
- No. 77 - Residual voltage on load side of an open circuit breaker
- No. 78 - Personal protective equipment (PPE) required with metal-clad switchgear
- No. 79 - Working space required around electrical equipment
- No. 80 - Special tests - type SDV7 distribution circuit breaker gearbox lubrication
- No. 81 - Arc-flash incident energy mitigation
- No. 82 - Continuous current capability in ambient temperatures other than 40 oC
- No. 83 - Arc-resistant construction for outdoor distribution circuit breakers
- No. 84 - Space heater - sizing and application principles
- No. 85 - Temperature limitations for user's power cables
- No. 86 - Use of unshielded cables for connections in medium-voltage switchgear and motor controllers
- No. 87 - Ground and test devices
- No. 88 - Application of maintenance grounds in switchgear
- No. 89 - Venting of exhaust gases from arc-resistant equipment
- No. 90 - Temperature ratings for external cables
