EN 50326 Conductors for Overhead Lines - Properties of Greases

The European standard “EN 50326 Conductors for overhead lines - Characteristics of greases” describes the characteristics of protective products, commonly known as greases, for the corrosion protection of bare overhead line conductors made of aluminium, aluminium alloy, steel wires or a combination of these wires.

For the purposes of this standard, the terms and definitions given in the standards “IEC 60050-466 International electrotechnical dictionary (IEV) - Part 466: Overhead lines” and “EN 50182 Conductors for overhead lines - Concentric layered multi-wire conductors with round wires” are valid.

According to this standard, greases should be designated as θ1Aθ2 or θ1Bθ2. Here, A and B define the grease type as follows:

Type: Greases applied without heating, i.e. greases consisting essentially of a stabilized mixture of mineral or synthetic oil and thickeners such as metal soaps or inorganic compounds.
Type B: Greases applied by heating. Greases composed of waxes and organic additives, such as petrolatum, associated with small amounts of mineral oil.
θ1 is the lowest temperature below 0 degrees at which the tests specified in this standard must be carried out.
θ2 is the highest temperature in degrees at which the tests specified in this standard must be carried out.

If requested by the user of the conductor, the values of θ1 and θ2 are specified by the grease buyer.

Examples:

20A150 type A grease has a temperature value of minus 20 degrees and plus 150 degrees.
20B110 type B grease has a temperature value of minus 20 degrees and plus 110 degrees.

The grease supplier must provide a unique name or code for the grease and retain details of the grease composition for verification purposes. The composition must include manufacturing tolerances and remain unchanged unless otherwise agreed upon with conductive use when marketing the grease under a specific name or code.

The requirements for grease are determined as follows:

The grease must meet the following requirements.
The grease must protect overhead line conductors from atmospheric corrosion in service and in storage. It must also meet the test requirements specified below.
The grease must remain on the conductor throughout the specified operating conditions and meet the specified requirements for the service life of the conductor. To demonstrate this, the test requirements specified below must be met.
To demonstrate that grease can be satisfactorily applied to a conductor with good adhesion, the test requirements specified below must be met.

No test should be carried out at a temperature higher than the maximum safe operating temperature specified by the grease supplier. All mandatory tests in this standard are carried out by the grease supplier. The grease tests specified in the standard “EN 50182 Conductors for overhead lines - Multi-stranded conductors with round wires and concentric layers” are carried out by the conductor manufacturer.

Type tests are designed to verify the main properties of a grease which depend on its composition. These tests are normally carried out only once for a particular grease supplier name or code, but should be repeated if the composition of the grease is changed and any of the test properties given in the table are changed.

Sample tests are designed to ensure the quality of the grease and its conformity to the requirements of this standard.

The tests specified in the table titled “Type and sample tests for grease” include:

Drop point
High temperature stability
Penetrability (type A)
Penetrability (type B)
Adhesion
Acidity / alkalinity index
Aging
Corrosion
Stability under steady-state conditions
Stability under short circuit conditions

Type B grease delivered in solid form, unless otherwise specified in these subclauses, must be preconditioned as follows in order to homogenize the grease before the specified 6tests: The grease is heated to 10 to 20 degrees above the temperature at which melting occurs and held at this temperature for 0,5 hours. The amount required for the tests is poured into test containers in liquid form and allowed to cool for at least 24 hours. Excess oil on the surface of type A grease as delivered is grounds for rejection.

In all tests mentioned in this standard, temperatures are measured using equipment with an accuracy of at least 1 degree.

For Type B grease, five dropping point determinations shall be made using the method given in ISO 2176. The minimum value of the five determinations shall be greater than or equal to θ2.

For Type A grease, high temperature stability tests shall be demonstrated by two tests. Oil separation shall be determined after 2 hour at θ1 using the method given in IP 121. The maximum amount of oil separated shall be a mass fraction of 0,2 percent. The dropping point test shall be carried out on five samples using the method given in ISO 2176. Type A grease may not have a well-defined dropping point. Tests may be stopped at θ2 plus 20 degrees unless the grease purchaser requests proof of the short circuit temperature.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "EN 50326 Conductors for overhead lines - Properties of greases" standard are also provided to businesses.