XLE Compound For 11kv Cables-PP 411 - 401 (CL)

Curable by exposure to moisture, for insulation of Power Cables and possessing excellent extrudability at output rate. PP 411 has been specially developed for cables upto 11KV. The special formulation and compounding techniques used ensure that the contamination level is kept within the required limits for this voltage grade.

PP 411 has general Melt Flow Index range of 0.5-0.8, which provides firm stability during extrusion, especially for the thick insulation required for high voltage. Silane Grafted Crosslinkable Polyethylene For Medium Voltage Power Cable Insulation.

Special Characteristics:

The compound utilizes the system for crosslinkable of polyethylene developed by Dow Coring and known as Sipolas. It is a two competent system comprising a Silylated Ethylene polymer . known as the graft PP411 and a masterbatch PP401 (CL) containing a crosslinking catalyst. The two material normally used in the ratio of 95 parts graft to 5 parts catalyst masterbatch.

Stored separately, these material are fairly stable but when mixed and exposed to moisture, crosslinking takes place.

This system allows the compound to be extruded as a normal thermoplastic which will then attain a high level of crosslinking in the processed form. The finished product has all the properties associated with polyethylene crosslinked by other methods.

Technical Characteristics

Properties- Physical & Mechanical Typical value Unit Test Method
Density 0.925 gm/cm3 ASTM – D- 1505
MFI at 190° C / 2.16 kg. 0.55 G / 10 PPIL

Unaged mechanical properties :

Tensile Strength 18 MPa IEC60811
Elongation at Break 650 % IEC60811

Mechanical Properties after ageing in Air oven, 168 hr. at 135° C:

Variation on tensile strength +6 % IEC60811
Variation on elongation at break -6 % IEC60811

Hot set test, 15 min. at 200° C, 0.2 N / mm2:

Elongation under load 100 % IEC60811
Permanent Elongation after Cooling 5 % IEC60811

Electrical Properties :

Power factor at 50 Hz at 23° C 0.0004 Nil IEC60250
Dielectric constant 2.2 --------- IEC60250
Volume Resistivity at 20° C 1.4*1016 Ohm.cm IEC502
Dielectric Strength 25 Kv / mm IEC60243

Contamination : (11 KV )

Contamination is measured by the use of Dyanascope's micrometer (x 200)
• level of contamination
1. a) no particle > 0.5 mm
b) max. particle 5 per 500 gm between 0.20 to 0.49 mm

Recommended Extrusion Conditions

Extruder :

Thermoplastic extruders will process PPIL Sioplas – type compound particularly if the screw is suitable for polyethylene extrusion. An extruder having L/D ratio of at least 20 and compression of 3:0:1 is recommended.

Extrusion temperature Conditions :As a guide the following temperature profile is recommended
Zone Zone 1 Zone 2 Zone 3 Zone 4 Head Die
Temperature 160° C 170 ° C 180° C 190° C 200° C 210° C
This profile may vary depending on extruder type, design and output
Screw water temperature: 60° C – 70° C
Screens: 30,80,30 (mesh apertures per linear inch)

Head And Tool Design :

The head and tools should be so designed to allow streamline flow without the possibility of stagnation material

Curing can be done in the following ways :

Conductor and Core Screens :

Compound PP 411/401 (CL) may be used in conjunction with deformation resistant thermoplastic Semiconducting material PPIL grade- P-10040-CB for conductor and insulation shield.

Cross-Linking or Cure :

This Curing can be done in the following ways :
By immersion in hot water at 80-85°C
• By exposure to low pressure steam (about 0.15 bar)
Following Factors are important for Cure :
• The ratio of conductor or insulation thickness
• Barrel diameter of the cable on the core is cured.

For thickness greater than 4 mm(approx) a maximum temperature of 85°C (which is below the phase change temperature of PP 411) is recommended, otherwise a set in the shape of the core wil l occur, preventing the core from lying flat after removal from the drum. Morover higher temperature may soften the outer semicon layer and cause damage.

The period required to obtain full cure will depend upon insulation thickness but typical periods in steam atmosphere are as under :

Insulation thickness Temperature Time
3-6 mm 85°C 3-6 mm

A significant decrease in cure time is possible through immersion in pressurized water (1.3bar) at a temperature of 85°C.

• By immersion in hot water at 90-95°C
• By exposure to low pressure steam (about 0.15 bar)
Following factors are important for cure
• The ratio of conductor to insulation thickness
• Barrel diameter of the cable on which the core is cured
Master Batch:

It is recommended that the catalyst master batch be thoroughly dried before usage at 60°C for 4hrs. at a depth not greater than 5 cm.

Storage :
Store under cold and dry conditions for best results
Packaging :
Moisture resistant aluminum laminated bags 25 kg.

This information is to the beat of our knowledge. The values of different parameters and operating conditions listed above are guidance only and should not be used for drawing specifications. The results & operating conditions may vary depending on methods of test and manufacturing / testing equipments.