Field of use
Composite insulators are used to equip overhead power lines and transformer stations with
nominal voltages of 20, 110, 220 and 400 kV, being part of the support and extension chains of
conductors, single, double (in parallel, in V) or multiple, for pollution zones II, III, IV.
They incorporate high-performance, high-tech materials such as: LSR liquid silicone rubber, fiber rods of
glass etc. and are produced through a modern technology, based on machines, raw materials and components supplied from established manufacturers, attested and certified by competent bodies.

The advantages of using LSR silicone rubber

The advantages of using liquid silicone rubber for the manufacture of composite insulators are:

♦ shows very good aging behavior and weather resistance;
♦ has high hydrophobicity, even for the most polluted areas;
♦ has excellent dielectric properties - arc resistance;
♦ it is fireproof;
♦ has a good adhesion to the core and reinforcements of the insulator;
♦ it is easily pigmentable;
♦ is resistant to acts of vandalism (hits, shootings);

Mechanical resistance structure of the composite insulators is provided by the glass fiber core.

End assemblies (rebars) they are made of forged steel, protected by hot galvanizing. They are fixed to the fiberglass core by crimping (with controlled pressure) in the trays of a special crimping machine whose parameters are monitored and controlled automatically.

Insulating tire it is made of silicone rubber. This covers the glass fiber core as well as the end of the fittings, ensuring sealing against water penetration.
Due to its shape, it realizes the required escape line, specific to pollution areas.

The silicone cover is poured under pressure into the mold. The casting mixture is prepared in an installation with an automated program for controlling and monitoring the parameters of the prescribed technological regime.

The designed models as well as the manufacturing technology are validated by design and type tests performed in renowned laboratories in Romania (Politehnica University of Bucharest, ICMET Craiova), in the Czech Republic (EGU HV Laboratory Prague) or Sweden (STRI Ludvika) in accordance with the following standards:

♦ SR CEI 1109 / CEI 61109
♦ Amendment 1 CEI 61109
♦ SR CEI 60060-1/CEI 60060-1
♦ SR CEI 383-1/CEI 60383-1
♦ SR EN 383-2/CEI 60383-2
♦ CEI 60437
♦ CEI 61467
♦ CEI 60695-11-10

Batch and individual mechanical tests are performed on a horizontal tensile test stand with the possibility of recording test diagrams.

I. Design trials
Samples to try and preliminary tests:

Visual control and dimensions (drawing): Identification
Individual mechanical test
The test at industrial frequency voltage in a dry environment

Presolicitation

Attempting to release the task suddenly
Thermomechanical test
Water immersion test

Verification attempts

Visual examination
Steep front voltage impulse test
Bypass voltage test at industrial frequency in a dry environment

Type load test of the assembled core
Samples to try

Visual check and dimensions (drawing): Identification

Mechanical load test

Determination of the average breaking load of the assembled insulator core
Control of the slope of the isolator load-time curve

Testing the clothing: testing for traces and erosion

1000 non-cyclical hours (according to point 5.3.3, SR CEI 1109)
5000 hours cyclically (according to Annex C, SR CEI 1109)

Tests of the core material

Dye penetration test
Water penetration test

II. Type tests
Lightning impulse voltage test in dry environment
Test at industrial frequency in humid environment
Holding test at impulse switching voltage in humid environment
Incercare mecanica sarcina-timp si incercarea etanseitatii intre armaturile          metalice si invelisul izolant
Incercare la arc de mare putere
Incercare la perturbatii radio

III. Incercari de lot
Verificarea dimensiunilor
Verificarea sistemului de cuplaj
Checking the tightness of the interface between the metal reinforcements and the insulating coating and the Specified Mechanical Load (SML)
Galvanization trial

IV. Individual trials
Identification of composite insulators
Visual examination
Individual mechanical test

Complete specific symbology for insulators

Example:

1 Composite Insulator (CI) with tension and support function
2 Nominal voltage (kV)
3 Pollution area / insulator construction variant (as applicable)
4 Specified Mechanical Load (SML) for traction
5 Type of end assembly
6 Lightning Impulse Voltage (STA)

Symbolization of end assemblies

Upon request, the end assemblies are executed in the requested variants.

Symbolization of the pollution zone

The data is according to SR CEI 815:1993

Operating conditions:
The composite insulators are intended to work in the moderate climate group (according to SR HD 478.2.1.S1:2002) specific to the continental European plateau in the following enviromental conditions:
Low temperature: -33 °C
High temperature: +40 °C
The maximum temperature for which the relative humidity is greater than or equal to 95%: +27 °C

Maximum altitude: 1500 m; 2000 m under the conditions of the appropriate choice of the escape line, in accordance with the insulation coordination regulations;
Relative air humidity:                     100 %
Maximum wind speed:                          145 km/h
Maximum solar radiation:                             1,18 kW/m
Maximum thickness of the ice layer: 24 mm

Lifetime of composite insulators is 30 years.

Warranty period is a minimum of 24 months from the installation of the insulator but no more than 30 months from the delivery, granted under the conditions of compliance with the packaging, transport and storage instructions specified by the supplier.

Installation instructions

CI-110 kV insulators can be delivered with protective armatures (horns or protective rings) that will be mounted on the end armatures of the insulators or on the chain elements, respecting the flashover distance k, in accordance with the provisions of NTE 003/04 /00.
Insulators with Un > 110 kV are provided with steel or aluminum guard rings embedded in insulator chains so as to comply with the required bursting distances k.
Depending on the application, guard rings can also be mounted on the end fittings of the insulators.