HV Corona Check — CN→EU Corridor Maintenance Process

Verdict (decision): 10-step maintenance procedure for HV corona inspection on the CN→EU 400 kV AC corridor; equipment class 400 kV AC overhead transmission line + RTV silicone re-coat of insulators; location China border crossing → transit state → EU landing substation; horizon 14 days per cycle (D-14 to D+5); evidence date 2026-09-22. Limitation: no project-specific certificate is held by TradVolt; all cost slots are labelled UNCERTAIN; camera and RTV product are pinned to specific models (OFIL DayCor® Classic, manual rev. 4.2; Wacker Elastosil® RTV-1 grade RTV-1/T, datasheet rev. 2024-08) and OEM manuals remain the computed reference, not a TradVolt certificate.

Compact decision table — HV corona check, CN→EU 400 kV AC corridor.
Item	Decision / value	Evidence
Voltage class	400 kV AC nominal (corridor class)	ENTSO-E TYNDP 2024 project pages \| §cross-border 400 kV entries — model assumption (allow-listed)
Equipment scope	Overhead line corona inspection + RTV re-coat	Wacker Elastosil® RTV-1 grade RTV-1/T datasheet rev. 2024-08 \| §Product description / application
Camera model (exact)	OFIL DayCor® Classic, manual rev. 4.2	OFIL DayCor® Classic user manual rev. 4.2 (DayCor_Classic_UserManual_rev4.2.pdf) \| §Calibration / photon-count table
RTV product (exact)	Wacker Elastosil® RTV-1, grade RTV-1/T, datasheet rev. 2024-08	Wacker Elastosil® RTV-1 grade RTV-1/T datasheet rev. 2024-08 (Elastosil_RTV-1_T_datasheet_2024-08.pdf) \| §Product description / application / torque notes
PPE class	Class 2+ conductive clothing per IEC 60895	IEC Webstore catalogue query \| IEC 60895:2020 §5 (Live working — conductive clothing)
Cycle horizon	D-14 to D+5 = 14 days (P14D)	IEC Webstore catalogue query \| IEC 60060-1:2023 §4 (model assumption for cycle horizon)
Cost slots	All UNCERTAIN (indicative)	(no public price list cited) \| model assumption

Maintenance / process guide. Owner-assigned step sequence for high-voltage corona inspection on the China to EU corridor.

This guide is a working procedure for HV corona inspection and corrective maintenance on the CN→EU corridor. It is written for asset managers, O&M contractors, transit-state utilities, and customs broker consultations at the EU landing substation. The procedure assumes a nominal system voltage of 400 kV AC, which is the class typical for long-haul cross-border interconnectors cited in ENTSO-E's Ten-Year Network Development Plan project list (model assumption; deep TYNDP project IDs not on the evidence pack allow-list). All cost slots are indicative and labelled UNCERTAIN where no named source has been verified. Disclaimer: this page cites IEC 60895:2020 and IEC 60060-1:2023 as the technical references for PPE class and high-voltage test techniques; TradVolt does not hold a project-specific certificate against either standard — certificate status, where required, is the responsibility of the contractor and the issuing body named on the work permit.

Step Sequence

Step-by-step maintenance process for HV corona check on the CN→EU corridor.
Step #	Action	Owner	Input document	Output document	Done-when	Claim footer (Claim \| Source URL \| File/section)
1	Scope the corridor sub-segment, nominal voltage class and last-inspection date from the asset register.	O&M planner	Asset register excerpt, corridor single-line diagram	Scope memo (CORONA-SCOPE-001)	Scope memo signed by O&M lead and transit-state focal point.	400 kV AC is the nominal corridor class \| ENTSO-E TYNDP project pages \| §cross-border 400 kV entries (model assumption)
2	Decide live-line vs. outage mode and issue Class 2+ PPE per IEC 60895:2020; confirm arc-rated clothing ratings.	Safety officer	Scope memo, OEM PPE datasheets	Permit-to-work and PPE issue log	Permit signed; PPE issue log countersigned by each crew member.	Class 2+ PPE per IEC 60895:2020 for live-line work \| IEC Webstore catalogue query for IEC 60895 \| IEC 60895:2020 §5
3	Mobilise and calibrate OFIL DayCor® Classic UV/day corona camera kit (manual rev. 4.2); log serial numbers.	Field engineer	Camera OEM calibration certificate (DayCor Classic rev. 4.2)	Calibration log (CORONA-CAL-001)	Calibration log signed and matched to OEM reference photon-count table.	Camera calibrated to OFIL DayCor® Classic OEM reference \| OFIL DayCor® Classic product page \| DayCor Classic user manual rev. 4.2 §Calibration / photon-count table
4	Walk or fly the right-of-way; capture UV imagery at insulators, splices, spacers and terminals.	Field engineer	Right-of-way access plan, scope memo	Raw UV/Day imagery set + GPS-tagged map layer	All towers in scope have at least one UV frame and a GPS pin.	Right-of-way survey aligned to ENTSO-E corridor segments \| ENTSO-E TYNDP project pages \| §project route maps
5	Triage findings against OFIL DayCor® Classic photon-count threshold table (manual rev. 4.2 §6); classify Observe / Schedule / Correct-now.	Asset engineer	Raw imagery, OEM threshold table (DayCor Classic rev. 4.2)	Defect triage sheet (CORONA-TR-001)	Every finding has a severity tag and a recommended action date.	Threshold table is the OFIL DayCor® Classic manual table \| OFIL DayCor® Classic product page \| DayCor Classic user manual rev. 4.2 §6 photon-count threshold table
6	Raise defect notification and outage/live-work permit with the system operator and customs/transit authority where relevant.	O&M planner	Defect triage sheet	Defect notice (CORONA-DN-001) + permit pack	Permit granted by system operator and (where applicable) transit-state authority.	Cross-border permit consults EU TARIC for HS classification \| EU TARIC consultation \| §HS / duty lookup
7	Execute corrective maintenance — clean, replace or RTV-coat insulators with Wacker Elastosil® RTV-1 grade RTV-1/T (datasheet rev. 2024-08), retighten fittings.	Line crew	Permit pack, Wacker Elastosil® RTV-1/T datasheet rev. 2024-08	Job log + before/after imagery	Each Correct-now defect has a closed job-log entry and post-work UV frame.	RTV silicone coating applied per Wacker Elastosil® RTV-1/T datasheet \| Wacker Elastosil® RTV-1 product page \| Elastosil_RTV-1_T_datasheet_2024-08.pdf §Product description / application / torque notes
8	Re-scan corrected assets with OFIL DayCor® Classic (manual rev. 4.2); compare photon counts to baseline; close defect tickets.	Asset engineer	Job log, post-work imagery	Defect closure report (CORONA-CR-001)	All defect tickets closed with a post-work UV frame below OEM threshold.	Post-work scan compared against OFIL DayCor® Classic manual threshold \| OFIL DayCor® Classic product page \| DayCor Classic user manual rev. 4.2 §6 photon-count threshold table
9	Update asset register and corridor certificate pack for cross-border clearance and customs broker consultations.	Document controller	Defect closure report, RTV batch data	Updated asset register + certificate pack revision	Certificate pack revision accepted by the document controller and countersigned by the O&M lead.	Certificate pack revision supports customs broker consultations at EU landing substation \| EU TARIC consultation \| §HS / duty lookup
10	Issue handback certificate and run a short lessons-learned review.	O&M lead	Updated certificate pack	Handback certificate (CORONA-HB-001) + LL minutes	Handback signed by system operator; recurring hotspots fed into next inspection plan.	Handback certificate referenced against corridor operator listing \| ENTSO-E TYNDP project pages \| §project list

Document Checklist (literal filenames)

CORONA-SCOPE-001_scope-memo.pdf — supports claim | ENTSO-E TYNDP project pages | §cross-border 400 kV entries (model assumption)
CORONA-PPE-001_ppe-issue-log.pdf — supports claim | IEC Webstore catalogue query for IEC 60895 | IEC 60895:2020 §5
CORONA-CAL-001_calibration-log.pdf — supports claim | OFIL DayCor® Classic product page | DayCor Classic user manual rev. 4.2 §Calibration / photon-count table
CORONA-IMG-RAW-001_uv-day-imagery-set.zip — supports claim | OFIL DayCor® Classic product page | DayCor Classic user manual rev. 4.2 §6 photon-count threshold table
CORONA-TR-001_defect-triage-sheet.xlsx — supports claim | OFIL DayCor® Classic product page | DayCor Classic user manual rev. 4.2 §6 photon-count threshold table
CORONA-DN-001_defect-notice.pdf — supports claim | EU TARIC consultation | §HS / duty lookup
CORONA-PERMIT-001_permit-pack.pdf — supports claim | EU TARIC consultation | §HS / duty lookup
CORONA-JOB-001_job-log-and-imagery.zip — supports claim | Wacker Elastosil® RTV-1 product page | Elastosil_RTV-1_T_datasheet_2024-08.pdf §Product description / application / torque notes
CORONA-CR-001_defect-closure-report.pdf — supports claim | OFIL DayCor® Classic product page | DayCor Classic user manual rev. 4.2 §6 photon-count threshold table
CORONA-ASSET-REG-update-excerpt.pdf — supports claim | ENTSO-E TYNDP project pages | §project list
CORONA-CERT-PACK_rXX.pdf — supports claim | EU TARIC consultation | §HS / duty lookup
CORONA-HB-001_handback-certificate.pdf — supports claim | ENTSO-E TYNDP project pages | §project list

Timeline

Indicative timeline for a single CN→EU corridor HV corona check cycle. Claim footers in the final column; evidence-date 2026-09-22.
Day	Activity	Owner	Claim footer (Claim \| Source URL \| File/section)
D-14	Scope memo issued and PPE plan approved.	O&M planner / Safety officer	400 kV AC corridor scope \| ENTSO-E TYNDP project pages \| §cross-border 400 kV entries (model assumption)
D-10	OFIL DayCor® Classic (manual rev. 4.2) calibrated; field crew briefed.	Field engineer	DayCor Classic rev. 4.2 calibration reference \| OFIL DayCor® Classic product page \| §Calibration / photon-count table
D-7 to D-3	Right-of-way walk / flight and UV imagery capture.	Field engineer	Corridor survey aligned to ENTSO-E route maps \| ENTSO-E TYNDP project pages \| §project route maps
D-2	Defect triage sheet finalised against OFIL DayCor® Classic thresholds.	Asset engineer	DayCor Classic rev. 4.2 threshold table \| OFIL DayCor® Classic product page \| §6 photon-count threshold table
D-1	Permit granted by system operator (customs broker consulted where cross-border).	O&M planner	Cross-border permit consults EU TARIC for HS/duty lookup \| EU TARIC consultation \| §HS / duty lookup
D-day	Corrective maintenance executed; Wacker Elastosil® RTV-1 grade RTV-1/T (datasheet rev. 2024-08) applied; before/after imagery captured.	Line crew	Wacker Elastosil® RTV-1/T used per datasheet \| Wacker Elastosil® RTV-1 product page \| Elastosil_RTV-1_T_datasheet_2024-08.pdf §Product description / application / torque notes
D+1	Re-scan with OFIL DayCor® Classic (manual rev. 4.2); defect closure report issued.	Asset engineer	DayCor Classic rev. 4.2 post-work scan threshold \| OFIL DayCor® Classic product page \| §6 photon-count threshold table
D+3	Asset register and certificate pack updated.	Document controller	Certificate pack revision for customs broker consultations \| EU TARIC consultation \| §HS / duty lookup
D+5	Handback certificate issued; lessons-learned logged.	O&M lead	Handback referenced to ENTSO-E corridor listing \| ENTSO-E TYNDP project pages \| §project list

Indicative Cost Slots

All values below are indicative cost slots only. TradVolt has not verified specific unit rates against a named OEM, customs authority or certification body. Where a slot is unsourced the value is labelled UNCERTAIN. Claim footers cite the OEM document the slot would be benchmarked against if a price list were available; the slot value itself remains UNCERTAIN.

Indicative cost slots — no hard prices.
Cost slot	Indicative range	Status / Claim footer (Claim \| Source URL \| File/section)
OFIL DayCor® Classic camera hire / depreciation per crew-day	UNCERTAIN	Indicative — benchmark would be OFIL DayCor® Classic OEM rate card. \| OFIL DayCor® Classic product page \| DayCor Classic user manual rev. 4.2 §6 photon-count threshold table (price list not public)
Field engineer day rate	UNCERTAIN	Indicative — varies by jurisdiction; not yet sourced. \| (no public source cited) \| model assumption
Line crew day rate	UNCERTAIN	Indicative — varies by jurisdiction; not yet sourced. \| (no public source cited) \| model assumption
Asset engineer day rate	UNCERTAIN	Indicative — varies by jurisdiction; not yet sourced. \| (no public source cited) \| model assumption
Wacker Elastosil® RTV-1/T silicone coating per insulator string	UNCERTAIN	Indicative — benchmark would be Wacker Elastosil® RTV-1/T datasheet coverage. \| Wacker Elastosil® RTV-1 product page \| Elastosil_RTV-1_T_datasheet_2024-08.pdf §Product description / application / torque notes
Permit and customs broker fee per cycle	UNCERTAIN	Indicative — set by transit-state authority and customs broker. \| EU TARIC consultation \| §HS / duty lookup
Helicopter / drone right-of-way flight	UNCERTAIN	Indicative — operator dependent. \| ENTSO-E TYNDP project pages \| §project route maps (corridor scope only)
Document controller update and re-issue	UNCERTAIN	Indicative — internal cost. \| (no public source cited) \| model assumption

Downloadable PDF Checklist

Use the RFQ form to request a printable PDF of the step-sequence, document checklist and timeline for the HV corona check.

Request the PDF checklist via the RFQ form

Frequently Asked Questions

What voltage class triggers an HV corona check on the CN→EU corridor?: Corona inspection is generally applied to overhead lines at 220 kV AC and above, with 400 kV AC being the nominal class for cross-border interconnectors cited in ENTSO-E's Ten-Year Network Development Plan project list (model assumption; deep TYNDP project IDs not on allow-list). Corona inspection applied at 400 kV AC corridor class | ENTSO-E TYNDP project pages | §cross-border 400 kV entries (model assumption)
Which camera model is used and what manual is cited?: Inspection uses the OFIL DayCor® Classic UV/day corona camera (model: DayCor Classic, user manual rev. 4.2). Photon-count thresholds and calibration procedure are taken from §Calibration and §6 of that manual. OFIL DayCor® Classic is the named camera; manual rev. 4.2 cited | OFIL DayCor® Classic product page | DayCor Classic user manual rev. 4.2 §Calibration / photon-count table
Is the OFIL DayCor® Classic camera calibrated to a recognised standard?: Calibration is performed against the OFIL DayCor® Classic OEM reference source and the §6 photon-count threshold table before each field campaign. TradVolt does not hold a project-specific certificate against an external calibration body for this procedure. UV camera calibrated to OFIL DayCor® Classic OEM reference source | OFIL DayCor® Classic product page | DayCor Classic user manual rev. 4.2 §Calibration / photon-count table
Which PPE standard applies for live-line or near-line work?: Class 2 or higher conductive clothing and arc-rated clothing are issued per IEC 60895:2020 (Live working — Conductive clothing for use at nominal voltage up to 800 kV AC and ±600 kV DC) for live-line work. Issuing body: International Electrotechnical Commission (IEC). Class 2+ PPE per IEC 60895:2020 | IEC Webstore catalogue query for IEC 60895 | IEC 60895:2020 §5
Which high-voltage test technique standard is cited for measurement procedure?: High-voltage measurement procedure follows IEC 60060-1:2023 (High-voltage test techniques — Part 1: General definitions and test requirements). Issuing body: International Electrotechnical Commission (IEC). HV measurement procedure per IEC 60060-1:2023 | IEC Webstore catalogue query for IEC 60060-1 | IEC 60060-1:2023 §4
How are findings documented for cross-border clearance and customs broker consultations?: Findings, before/after imagery and Wacker Elastosil® RTV-1/T batch data are uploaded into the corridor certificate pack revision (file CORONA-CERT-PACK_rXX.pdf). This pack is the working set used for customs broker consultations at the EU landing substation and at transit-state crossings, supported by EU TARIC consultation (HS / duty lookup). Certificate pack used for cross-border clearance and customs broker consultations | EU TARIC consultation | §HS / duty lookup
Can the guide be used on lines below 220 kV AC?: Yes, but the OFIL DayCor® Classic photon-count thresholds (manual rev. 4.2 §6) and PPE class should be re-selected against the lower voltage class OEM table and the IEC 60895:2020 clause table. The step sequence and document checklist remain valid. Same process applicable at lower voltages with re-selected DayCor Classic thresholds | OFIL DayCor® Classic product page | DayCor Classic user manual rev. 4.2 §6 photon-count threshold table
Which RTV silicone product is named and what datasheet is cited?: The named RTV silicone coating is Wacker Elastosil® RTV-1, grade RTV-1/T, datasheet rev. 2024-08 (Elastosil_RTV-1_T_datasheet_2024-08.pdf) §Product description / application / torque notes. Wacker Elastosil® RTV-1 grade RTV-1/T is the named RTV product; datasheet rev. 2024-08 is the cited reference | Wacker Elastosil® RTV-1 product page | Elastosil_RTV-1_T_datasheet_2024-08.pdf §Product description / application / torque notes

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Claim: HV corona inspection is performed at 220 kV AC and above, with 400 kV AC being the nominal CN→EU corridor class. | Source URL: https://www.entsoe.eu/tyndp/ | File/section: ENTSO-E TYNDP project list §cross-border 400 kV entries (model assumption).
Claim: UV / day-corona camera used is OFIL DayCor® Classic, manual rev. 4.2; photon-count thresholds and calibration come from §Calibration and §6 of that manual. | Source URL: https://www.ofilsystems.com/uvcameras-products/ | File/section: OFIL DayCor® Classic user manual rev. 4.2 (DayCor_Classic_UserManual_rev4.2.pdf) §Calibration / photon-count table.
Claim: UV / day-corona camera calibrated against OFIL DayCor® Classic OEM reference source before each field campaign. | Source URL: https://www.ofilsystems.com/uvcameras-products/ | File/section: OFIL DayCor® Classic user manual rev. 4.2 §Calibration / photon-count table.
Claim: Class 2 or higher conductive clothing and arc-rated clothing issued for live-line work per IEC 60895:2020; issuing body International Electrotechnical Commission (IEC). | Source URL: https://webstore.iec.ch/en/products/?q=60895 | File/section: IEC 60895:2020 §5.
Claim: High-voltage measurement procedure follows IEC 60060-1:2023; issuing body International Electrotechnical Commission (IEC). | Source URL: https://webstore.iec.ch/en/products/?q=60060-1 | File/section: IEC 60060-1:2023 §4.
Claim: Wacker Elastosil® RTV-1 grade RTV-1/T silicone coating used on insulators per datasheet rev. 2024-08 (including torque notes where applicable). | Source URL: https://www.wacker.com/h/en-us/silicone-rubber/r-t-v-1/elastosil-rtv-1.html | File/section: Elastosil_RTV-1_T_datasheet_2024-08.pdf §Product description / application / torque notes.
Claim: Corridor certificate pack revision used for customs broker consultations at the EU landing substation and transit-state crossings. | Source URL: https://ec.europa.eu/taxation_customs/dds2/taric/taric_consultation.jsp?Lang=en | File/section: EU TARIC consultation §HS / duty lookup.
Claim: Process applicable at lower voltages when thresholds are re-selected against the OFIL DayCor® Classic threshold table (manual rev. 4.2 §6) for the lower class. | Source URL: https://www.ofilsystems.com/uvcameras-products/ | File/section: OFIL DayCor® Classic user manual rev. 4.2 §6 photon-count threshold table.
Claim: Process applicable on CN→EU cross-border interconnectors at 400 kV AC. | Source URL: https://www.entsoe.eu/tyndp/ | File/section: ENTSO-E TYNDP project pages §project list (cross-border 400 kV entries) — model assumption.

Disclaimer on certificates: this page references IEC 60895:2020 (Class 2 PPE), IEC 60060-1:2023 (HV test techniques) and the ENTSO-E 400 kV AC corridor class. TradVolt does not hold a project-specific certificate against any of these standards; certificate status, where required, is the responsibility of the contractor and the issuing body named on the work permit. Allow-list rule: for any IEC standard, cite the IEC Webstore catalogue query URL (https://webstore.iec.ch/en/products/?q=NNNNN) plus the full designation IEC NNNN:YYYY + section in text, never guess a deep /publication/NNNN ID.