Project Overview
DualTech Conseil carried out witnessing of high-voltage type tests on 345kV insulator string assemblies intended for a major transmission project in North America. The tests were performed over a two-week period at Sediver High Voltage Laboratory in Bazet, France, and covered Radio Interference Voltage (RIV), Corona, and dielectric withstand testing on representative insulator assemblies and associated hardware.
Equipment Details
- 345kV Insulator String Assemblies — 7 configurations tested
- Insulator units: F 300PU/195 Z porcelain / glass
- Conductor: AACSR JOREE / AACSR GRACKLE
- Manufacturer: Sediver
Assemblies Tested
- 345kV I Suspension Assembly — Outer Phases (1 × 14 bells)
- 345kV V Suspension Assembly — Middle Phase (2 × 14 bells)
- 345kV V Jumper Support Assembly — Middle Phase (2 × 14 bells)
- 345kV Double V Suspension Assembly (2 × 2 × 16 bells)
- 345kV Single Tension Assembly (1 × 16 bells)
- 345kV Double Tension Assembly (2 × 16 bells)
- 345kV Quad Tension Assembly (4 × 18 bells)
Scope of Inspection
Radio Interference Voltage (RIV) Test
RIV tests were witnessed on the 345kV assemblies at the specified voltage level of 220 kV. The acceptance criterion was radio noise level not exceeding 56 dB(μV). All reviewed and witnessed results were within the specified acceptance limit.
Corona Test
Corona tests were carried out under dark-room conditions. No visible positive corona discharge was observed at the specified voltage of 220 kV for the tested assemblies.
Wet Power Frequency Withstand Voltage Test
Performed in accordance with IEC 60383-2 and IEC 60060-1. Acceptance criterion: 525 kV. No flashover, puncture, breakdown or insulation failure was observed.
Wet Switching Impulse Voltage Test
Performed in accordance with the approved test plan. Acceptance criterion: 950 kV. Waveform responses and peak values remained stable and within tolerances.
Dry Lightning Impulse Voltage Test
Performed in accordance with the approved test plan. Acceptance criterion: 1175 kV. No abnormal discharge activity or equipment malfunction was observed.
Documentation Review
Prior to testing, each setup was verified against approved drawings and the test program — including assembly identification, insulator string configuration, fittings, conductor arrangement, grounding, high-voltage connections, arcing distances, and measuring instruments. Atmospheric conditions were recorded and correction factors calculated per IEC 60060-1. Calibration status of all measuring equipment was reviewed and found acceptable.
Standards Applied
- IEC 60383-2:1993 — Insulators for overhead lines with nominal voltage above 1,000 V
- IEC 60060-1 — High-voltage test techniques
- IEC 60437 — Radio interference test on high-voltage insulators
- CSA C108.3.1 — Canadian radio noise performance requirements
- IEC 61284 — Overhead lines — requirements and tests for fittings
Outcome
The tested 345kV insulator string assemblies demonstrated acceptable electrical and dielectric performance under the witnessed and reviewed test conditions. No major non-conformity was identified during the inspection period. One drawing/configuration discrepancy (related to the V Jumper Support Assembly) was identified, corrected, and preliminarily accepted before continuation of the tests. Final acceptance remains subject to end client review and approval of the complete test reports, dimensional records and calibration certificates.
