11 kV Composite Pin Insulator for Overhead Distribution Lines

11 kV composite pin insulator at a glance

• Application: supports and insulates the conductor on 11 kV overhead distribution lines.
• Construction: fibre reinforced plastic core, silicone rubber housing with sheds, and a metal pin fitting.
• Rated voltage: 11 kV.
• Rated mechanical bending load: 5 kN, 10 kN or 12.5 kN, depending on the model.
• Structure height: 280 mm to 320 mm; minimum creepage distance 380 mm to 450 mm.
• Electrical ratings: lightning impulse withstand voltage 95 kV to 105 kV peak; power frequency 1 min wet withstand voltage 45 kV.

1. What this insulator is used for

A composite pin insulator carries the conductor on a distribution line and holds it at a fixed distance above the earthed cross arm. It consists of a fibre reinforced core, a silicone rubber housing with sheds, and the metal fitting that forms the pin. Compared with a porcelain pin insulator it is lighter, it resists vandalism and impact damage, and it performs better on polluted coastal and industrial routes, which is why composite pin types are widely used on 11 kV and 33 kV distribution networks.

The FPQ-11 series covers the 11 kV class. The models differ in the rated mechanical bending load and in the creepage distance, so the same line can be fitted with a higher mechanical rating where the span or the conductor tension requires it, or with a longer creepage distance on a polluted or coastal route.

2. Standards applied

• IEC 61109 – Composite suspension and tension insulators for overhead lines with a nominal voltage above 1000 V: definitions, test methods and acceptance criteria.
• IEC 61952 – Composite line post insulators for overhead lines with a nominal voltage above 1000 V, which covers the pin and post types of this construction.
• GB/T 19519 – the Chinese national specification for composite insulators for a.c. overhead lines.
• ANSI classes – applied instead of the IEC classes where the purchaser specifies them.

3. Technical parameters

Main technical parameters of the 11 kV composite pin insulator range:

Construction and service conditions of the composite pin insulator range:

• Whole injection moulding of the silicone rubber housing, with the end fitting crimped onto the glass-fibre core by a compression process.
• Sheath thickness 5 mm or more and of uniform thickness, in line with the IEC requirements for the housing.
• Service conditions: ambient temperature -40 degrees Celsius to +40 degrees Celsius, altitude up to 3000 m, wind velocity up to 35 m/s, ice thickness up to 10 mm, seismic intensity up to 8 degrees.
• Tested to the requirements of IEC 61109 and IEC 61952 and to the Chinese national specification GB/T 19519; the ANSI classes are applied where the purchaser specifies them.
• Corona rings are fitted on the higher voltage classes where the system voltage requires them.
• Manufactured to the customer’s requirement where a project needs a different height, creepage distance or fitting.

4. Key features

• Light weight: a composite pin insulator is far lighter than the porcelain equivalent, which makes handling and installation easier and reduces the load on the cross arm.
• Resistance to impact and to vandalism, which is a common cause of loss on distribution networks.
• Hydrophobic silicone rubber housing that performs well on polluted, coastal and industrial routes; no zero value detection is needed as with a porcelain or glass unit.
• Uniform sheath of 5 mm or more over the core, protecting the interface against moisture ingress.
• End fitting crimped onto the core with an automatic damage inspection system on the production line.
• Supplied to the customer’s requirement where the project needs a different height, creepage distance or fitting.

5. Typical applications

• 11 kV overhead distribution lines – urban, suburban and rural feeders.
• Coastal and industrial routes – where salt or industrial pollution would require frequent cleaning of a porcelain insulator.
• Replacement of porcelain pin insulators – on existing lines, to reduce breakage and maintenance.
• Distribution projects – new builds and network reinforcement for utilities and contractors.

6. Frequently asked questions

1. What is a composite pin insulator?

A pin type insulator built from a fibre reinforced core, a silicone rubber housing with sheds and a metal pin fitting. Unlike a porcelain pin insulator it is a single moulded and crimped unit rather than a ceramic body cemented to a pin.

2. Which model should I choose?

Choose by the rated mechanical bending load the line requires and by the creepage distance the environment requires. FPQ-11/5 is the 5 kN class, FPQ-11/10 the 10 kN class and FPQ-11/12.5 the 12.5 kN class, with creepage distances from 380 mm to 450 mm.

3. What is creepage distance and why does it matter?

It is the shortest distance along the surface of the insulator between the two electrodes. The longer it is, the better the insulator performs under pollution and wetting, which is why a coastal or industrial route is specified with the longer creepage model.

4. Can these insulators be made to my own drawing?

Yes. The range is produced to the customer’s requirement where a project needs a different height, creepage distance, shed profile or end fitting.

5. Do composite pin insulators need zero value testing?

No. That check applies to ceramic and glass units, which can lose their insulating value without any visible sign. A composite insulator does not have that failure mode.

6. Which standards are the ratings taken from?

IEC 61109 and IEC 61952, with GB/T 19519 as the Chinese national specification. Where the purchaser specifies ANSI, the ANSI classes and their ratings are applied instead.

Related composite insulator products

The same construction is supplied for the higher distribution class in the 33 kV composite pin insulators. The core and the housing material are the FRP / ECR core rod for composite insulators and the silicone rubber material for polymer insulators, and the machines that produce them are listed under insulator production machines.