MV Switchgear Primary-Design Review: A 75-Point Engineering Checklist

A primary-design review must prove that ratings, geometry, materials, interfaces, tests and site installation form one coherent MV switchgear system. The following 75-point checklist is a gate-review tool: every item requires objective evidence, an owner and a status—not a verbal “checked.”

Use it at concept, design freeze, pre-type-test/FAT and pre-energisation. Tailor it to the contract and current standards; mark an item N/A only with written justification. It complements—not replaces—the full IEC documents and manufacturer design rules.

How to record the review

Field	Required entry
ID/status	Open, conditionally accepted, accepted or N/A with reason
Requirement	Contract/standard clause and revision
Evidence	Drawing, calculation, report, test, certificate or site record
Owner/due date	Named discipline/person and closure date
Risk	Safety, performance, schedule and revalidation consequence
Closure	Independent reviewer, date and configuration baseline

A. Design basis and standards (1–5)

Design-basis freeze: Is the single controlled document approved for network, ratings, service, environment, layout, operation, maintenance, future extension and responsibility boundaries?
Standards register: Are exact IEC/IEEE/local editions, amendments, corrigenda, precedence and deviations listed, with current references such as IEC 62271-200:2021+AMD1:2024?
Service conditions: Are ambient, altitude, humidity/condensation, pollution, solar/corrosive/seismic exposure, frequency and special service conditions quantified rather than labelled “normal” without verification?
Functional philosophy: Are fixed/withdrawable architecture, compartments, partition class, LSC, IAC, access sides, interlocking and isolation/earthing philosophy aligned with operating procedures?
Interface control: Are civil, cable, transformer/bus-duct, control/SCADA, earthing, fire/HVAC and pressure-duct interfaces on signed revision-controlled drawings?

B. Network studies and ratings (6–10)

Voltage/insulation: Are nominal/highest voltage, frequency, insulation level and earthing based on an approved network and insulation-coordination study?
Continuous current: Do feeder, bus, coupler and neutral/earth current ratings include contingency, harmonics, load profile, ambient and future assumptions?
Short-circuit duty: Does the IEC 60909 study provide initial symmetrical, peak, duration and fault cases at each section, including motor/generator contribution?
Switching duties: Are transformer/motor/reactor/capacitor/cable switching, inrush, out-of-phase, restrike/reignition and TRV duties matched to device ratings?
Auxiliary ratings: Are AC/DC control voltage ranges, ripple, voltage drop, battery autonomy, coil burden and loss-of-supply behaviour defined?

C. Single-line, zones and operating states (11–15)

Topology: Does the primary single-line match every physical bus section, tee-off, transformer, VT, earth switch and future connection?
Operating-state table: Are normal, transfer, maintenance, test, emergency and backfeed states analysed for ratings and safety?
Protection zones: Are CT positions/polarities, breaker-failure zones and blind spots mapped around buses, cables and removable contacts?
Interlock matrix: Does permitted/prohibited operation cover breaker, disconnect/test position, shutters, earth switches, doors and keys without procedural gaps?
Isolation points: Can each work zone be isolated, proved dead, discharged and earthed while adjacent required circuits remain safely segregated?

D. Dielectric and insulation coordination (16–20)

Withstand selection: Are power-frequency, lightning impulse and longitudinal/phase-phase levels coordinated to system surges and protected equipment?
Clearance: Are phase-earth/phase-phase clearances checked at worst tolerance, altitude, every device position and maximum fault/seismic/thermal displacement?
Creepage/surfaces: Are material, contamination, condensation and actual application of pollution standards justified—without applying outdoor insulator rules blindly indoors?
Field control: Are sharp edges, terminals, screens, barriers, triple points, cable stress-control and partial-discharge-sensitive interfaces modelled/qualified?
Surge protection: Are arrester MCOV/TOV/energy/protective level and lead inductance coordinated with cables, transformers, motors/generators and VT circuits?

E. Continuous-current and thermal design (21–25)

Loss model: Are conductor AC resistance, proximity/skin, joints, breaker/disconnect, CT/VT and enclosure eddy/hysteresis losses quantified?
Heat transfer: Are ambient, convection/radiation, compartment coupling, end panels, ventilation recirculation and room/HVAC interfaces represented?
Material limits: Are permitted temperatures/temperature rises assigned to contacts, insulation, seals, terminals, cables, coils/electronics and accessible surfaces?
Cooling dependency: If fans/filters are needed, are redundancy, monitoring, failure alarm/derating/trip and maintenance state defined and tested?
Thermal evidence: Does temperature-rise evidence match worst current path, enclosure, connections, cable quantity and cooling; are model/test margins and variant rules documented?

F. Short-circuit forces and withstand (26–30)

Current waveform: Are peak asymmetry, RMS/time and source decrement applied to mechanical and thermal checks rather than one kA value?
Electromagnetic geometry: Are straight spans, bends, tees, risers, parallel paths, cables and return conductors analysed in three dimensions where necessary?
Load path: Are forces traced through conductors, joints, insulators, brackets, enclosure, shipping splits, base rails and anchors?
Dynamic response: Are natural modes, damping, transient amplification, contact/slip/plasticity and minimum dynamic clearance addressed?
Post-test criteria: Do reports inspect joint/contact/support damage, residual deformation, dielectric clearance, resistance and continued operability after short-time/peak tests?

G. Busbars, joints and thermal movement (31–35)

Bus material/section: Are copper/aluminium grade, conductivity, plating, AC loss, net section at holes and tolerances controlled?
Joint design: Are contact surfaces, pressure distribution, bolt/preload/washer/lubrication, creep/relaxation and transition-metal corrosion validated?
Support scheme: Are fixed/sliding supports, expansion joints, flexible links and long-lineup thermal movement unambiguously defined?
Routing: Are phase geometry, joint count, bends, magnetic loops, tool access and fault-clearance movement optimised together?
Production QA: Are surface preparation, hardware, calibrated torque/preload, witness marking, resistance baseline and foreign-material exclusion recorded?

H. Switching and instrument devices (36–40)

Breaker/switch ratings: Are all continuous, interrupting/making, TRV, capacitive/inductive, endurance and operating-sequence duties covered by applicable certificates?
Withdrawable contacts: Are six-DOF tolerance, engagement/overlap, force, plating, racking signature and position correspondence specified and verified?
Earthing switch: Is the full making/short-time current path, contact speed/bounce, support and interlocking proven?
CT/VT/LPIT: Are ratio/class/burden/transient performance, polarity, secondary safety/earthing, fuses/backfeed and physical protection zones coherent?
Device mounting: Are terminal loads, mass/seismic/transport support, heat, clearances, failure vents and safe replacement/test envelopes verified?

I. Cable interfaces and restraint (41–45)

Cable schedule: Are exact construction, conductor/screen/armour, diameter/tolerance, installation/final radius, temperature and accessory part numbers frozen?
Routing: Does a 3D centreline prove bends, straight termination length, phase crossing, tools, replacement and trench/floor tolerance?
Termination/interface: Are lug/separable interface, load-break/dead-break function, terminal loads, cutbacks, torque/compression and test adapters controlled?
Cleats: Does IEC 61914 evidence match cable diameter/formation, peak current, spacing, bracket, fasteners and mounting surface?
Entry/bonding: Are non-magnetic single-core plate needs, glands/seals, screen/armour fault duty, CBCT routing, IP/fire and IAC boundary coordinated?

J. Earthing and fault-return paths (46–50)

Fault map: Is each credible enclosure, cable, device and earth-switch fault traced to the station grid with its protection clearing/backup time?
Earth-bus sizing: Are current division, I²t, peak force, net section, joints, branches and external grid leads calculated?
Protective bonding: Are frames, partitions, doors/removable parts and trucks bonded without relying on paint, hinges, wheels or incidental contact?
Shipping/site joints: Are earth split links and grid terminals accessible, corrosion-controlled, torque/process-recorded and tested before energisation?
Functional earths: Are relay/VT/CT/screen/EMC earths kept architecturally correct so small conductors do not become primary fault paths?

K. Enclosure, compartments and internal arc (51–55)

Compartment architecture: Do partitions/shutters/access rules preserve declared PM/PI, LSC and safe adjacent-compartment conditions?
IAC definition: Are accessibility sides, current/duration, indicator setup and room/wall/ceiling/floor installation matched to the test report?
Pressure path: Are compartment volume, flaps, ducts, bends, supports/outlet, cable/brace obstructions and gas transfer controlled?
Doors/covers: Are latches, hinges, windows, penetrations, fasteners, IP/IK and projectile risks verified under pressure/impact duties?
Human safety: Are exhaust direction, escape/access, remote operation and residual arc-flash risk assessment treated separately from IAC classification?

L. Structure, seismic, transport and foundation (56–60)

Enclosure structure: Are thin-sheet buckling, fastener/weld/latch failure, stiffness and functional displacement checked—not von Mises stress alone?
Seismic: Does IEC 62271-207:2023 evidence state RRS/TRS, damping, axes, configuration, functionality, anchors and site boundary?
Transport: Are route/environment, packaging, lift/COG, braces/register, impact indicators, storage and receiving quarantine specified?
Foundation: Are floor elevation/level/flatness/straightness, gauge lengths, supports/shims/grout, anchors and survey method manufacturer-specific?
Reassembly: Do shipping-split procedures restore frame, main/earth bus, secondary wiring, interlocks, pressure duct and qualification boundary with records?

M. Layout, constructability and maintainability (61–65)

3D envelopes: Are electrical, thermal, fault movement, installation, operation, maintenance, mechanism and arc-pressure envelopes checked in every equipment state?
Panel footprint: Is width/depth/height optimised against total room/aisle/trench/HVAC and lifecycle cost rather than width alone?
Task analysis: Can qualified personnel perform racking, isolation, earthing, testing, torque and replacement with PPE/tools and adjacent-live restrictions?
Heavy components: Are lift points, removal path, temporary stability, component mass and ceiling/door/floor capacity documented?
Future extension: Are electrical/thermal/short-circuit/IAC/seismic end conditions, space, bus joints, cable routes and outage method genuinely feasible?

N. Type-test validity and configuration control (66–70)

Test matrix: Are all required IEC 62271/product type tests mapped to exact offered functional units, ratings and configurations?
Reference evidence: Do reports include tested-object drawings/BOM, test values, installation, instrumentation, observations and post-test criteria—not certificate summaries only?
Extension analysis: Is IEC TR 62271-307:2024 applied test-by-test with quantified influential parameters, validated models and explicit validity limits?
Substitutions: Do component/material/supplier/firmware/site deviations trigger multidisciplinary review before release, with fleet impact assessed?
Critical controls: Are dimensions, materials, gas, fasteners, loss, volume, ventilation and processes that preserve validity flagged in PLM/drawings/inspection plans?

O. FAT, SAT, handover and lifecycle (71–75)

Routine/FAT: Do tests cover primary/earth resistance, dielectric, operation/interlocks, wiring, timing, CT/VT, protection/control and as-built visual/dimensional checks?
SAT: Are foundation/splits/cables/earth/grid, insulation limits, phasing, trip/close, protection functional, communications and local/remote switching verified safely?
Baselines: Are breaker timing/travel/coil, contact resistance, thermal, PD/insulation where specified, gas/density and condition-monitoring baselines captured with methods?
Handover: Are approved as-builts, settings/configurations, certificates/reports, calculations, manuals, spares/tools, training and unresolved punch-list risks transferred?
Lifecycle plan: Are inspection/maintenance triggers based on duty/condition, post-fault/arc/seismic actions, obsolete parts, modifications and periodic validity/safety review defined?

Review outcome and stop-work criteria

Do not freeze, manufacture or energise while any red issue affects dielectric clearance, fault withstand, protective earth, internal-arc boundary, isolation/interlock, breaker duty, cable constructability or test validity. Conditional acceptance must state the exact temporary condition, risk control, owner, evidence and expiry; it is not a device for moving unresolved engineering into site work.

Minimum final review pack

approved design basis, standards/deviation and interface registers;
network, insulation, short-circuit, thermal, mechanical, IAC and earthing studies;
primary/secondary schematics, layouts, BOM and tolerance models;
type/routine/FAT/SAT reports and IEC TR 62271-307 dossier;
civil/foundation, cable, pressure-duct, seismic and transport records;
closed review log with evidence links, independent approvals and configuration ID.

Independent review sampling

Do not close the checklist by document-presence audit alone. Independently recalculate or trace representative high-risk chains: maximum short-circuit case to support/anchor; cable data to bend/cleat/terminal load; CT ratio/polarity to relay setting/trip; IAC report to installed duct/wall; and type-tested configuration to production BOM. Select at least one end panel, coupler, VT panel, highest-current unit and most congested cable compartment.

record assumptions and raw values used in the sample;
verify drawing/BOM/model revisions are mutually consistent;
follow open interfaces into civil, protection and commissioning packages;
expand sampling when one discrepancy indicates a systemic control failure;
require new baseline approval after closure, not isolated redline acceptance.

Core references

Safety note: The checklist supports competent engineering review; it is not permission for unqualified inspection or energised access. Apply the project safety system, manufacturer procedures and governing regulations at every test and work stage.