IEC 61394:2011

Overview

IEC 61394:2011 - "Overhead lines - Requirements for greases for aluminium, aluminium alloy and steel bare conductors" specifies performance, designation and test methods for greases used to protect bare overhead conductors from atmospheric corrosion. The standard covers both greases applied cold (Type A) and petrolatum‑type greases applied hot (Type B), and defines type tests and sample tests to verify composition, stability and protective performance in service and storage.

Key technical topics and requirements

• Designation system: Greases are designated as θAθ or θBθ, where the first θ is the minimum low‑service temperature (°C) and the second θ is the maximum temperature (°C) (e.g., 20A150, 20B110).
• Types:
  • Type A: mineral/synthetic oil + thickeners, applied cold; may lack well‑defined drop point.
  • Type B: petrolatum/microcrystalline wax‑based, applied hot.
• Main tests and limits:
  • Drop point (ISO 2176): minimum of five determinations ≥ declared θ2; Type A may stop at θ2 + 20 °C if no clear drop point.
  • High‑temperature stability (Type A): oil separation (IP 121) at θ2 for 1 h ≤ 0.2% mass.
  • Penetrability (ISO 2137, 25 °C): Type A mean ≥ 70 (×0.1 mm); Type B between 120–180 (×0.1 mm); sample results ±20% of type test.
  • Low‑temperature adherence: aluminium coupon (100×100×1 mm) coated with 0.50±0.05 mm film, conditioned ≤ θ1 for 1 h, bent around a 25 mm mandrel - no cracking or flaking.
  • Acidity/alkalinity (Type B): index ≤ 2.0 before ageing, ≤ 2.5 after ageing (method in Annex A).
  • Ageing: Type B preconditioned 20 °C above melting for 168 h; post‑ageing penetrability and acidity checked.
  • Corrosion tests: coated coupons exposed to seven 24 h sulphurous cycles (first 8 h: RH >90%, 0.067% SO2, 40±3 °C).
  • Stability on conductor: procedures for high‑temperature and short‑circuit stability are included (normative annexes).

Practical applications and users

• Who uses IEC 61394: transmission/distribution utilities, conductor manufacturers, grease suppliers, testing laboratories, procurement/specification engineers and asset‑management teams.
• Practical value:
  • Specify grease performance in tenders and material standards for overhead line protection.
  • Guide laboratory type testing, factory sample testing and acceptance criteria.
  • Aid suppliers to assign unique product identifiers and maintain composition records.
  • Ensure long‑term corrosion protection, storage stability and reduced maintenance on aluminium, aluminium‑alloy and steel conductors.

Related standards

• IEC 60068‑2‑11 (salt mist testing)
• ISO 2137 (cone penetration of greases)
• ISO 2176 (dropping point of greases)

Keywords: IEC 61394, overhead lines, conductor grease, corrosion protection, aluminium conductors, grease testing, drop point, penetrability, ageing test.