3M Terminations | Surface Tracking on Medium Voltage Cable Terminations

Published 04 Oct 2024

Surface Tracking – 3M Medium Voltage Cable Terminations

Surface Tracking on Cable Terminations

Surface tracking is the irreversible damage and degradation on the surface of a medium or high voltage cable accessory or insulative material, such as a cable termination, due to the formation of conductive, carbonized paths.

Tracking results when discharges cause carbon to be left on an insulating surface as a result of the degradation caused by the heat of the discharge. This carbon deposit will grow to eventually create a continuous conducting path, which will lead to catastrophic failure.

Cold Shrink & Condensation In Medium Voltage Switchgear & Cable Terminations

Hydrophobic silicone Cold Shrink terminations provide excellent performance in Medium Voltage electrical equipment, such as switchgear, where cables endure temperature fluctuations caused by thermal cycling when under load – this “heating and cooling” effect condensates potentially causing premature partial discharge at the cable termination point. 3M Cold Shrink technology has a material tendency to reject and repel moisture accumulation and thereby reducing the probability for discharge-initiated erosion and tracking on medium/ terminations.

N2XS(F)2Y Cable Terminations 12/20 22kV 24kV

Energising Data Centres | The QTIII range of MV Terminations are approved and in widespread service throughout the data centre sector for 12/20 (24)kV connection of N2XS(F)2Y Medium Voltage Cables with XLPE Insulation, Copper Wire Screen and Stranded Copper Conductor to BS EN 60228 into electrical switchgear equipment.

Thorne & Derrick supply LV HV Cable Accessories, Substation & Electrical Eqpt to EPC's and Power Cable & Jointing Contractors working on the design, construction and maintenance of UK, European and international data centres.

Surface Tracking Causes

Carbonized paths can occur from the dielectric breakdown of insulation, and/or by the introduction of contaminants on the surface that allow for electrical discharges across the surface.

The 3 factors that enable surface tracking to occur on cable terminations (MV HV):

Contamination	Moisture	Voltage
Dirt/Dust	Rain/Mist/Snow	Electrical Stress
Salt	Condensation
Chemicals	Fog
Pollutants	Humidity
Other particulates

Hydrophobicity

3M Terminations | Protecting Against Tracking

Tracking is defined as a process that produces localised irreversible deterioration on the surface of an insulator, resulting in the loss of the insulating function by the formation of a conductive path on the surface of the insulator.

Silicone is an excellent track resistant material and is hydrophobic, repelling water and making the insulator self-cleaning which results in a dryer surface and lower leakage currents. 3M outdoor cable terminations include 3M rain sheds which disrupt any wet leakage paths that occur in industrial environments and also allows the creepage distance of the termination to be much shorter.

Insulator Skirts

Use of skirts on cable terminations increases the creepage distance (leakage distance) between the voltage source and ground plane. The undercut skirts disrupt wet leakage paths that occur in outdoor environments.

Advanced Materials

Insulators and skirted assemblies are made of formulated silicone rubber, which has excellent tracking resistance and hydrophobic properties. Special High K materials formulated to effectively control electrical stress.

Effective Stress Control

Electric field stresses are distributed in a controlled manner along the entire termination length. Voltage stress concentrations on the insulator surface are kept below 15 V/mil at rated voltage.

Further Reading

3M DISTRIBUTORS, STOCKISTS & SUPPLIERS

Thorne & Derrick provide competitive prices and fast delivery from stock for the complete range of 3M Scotchcast and Cold Shrink cable joints, terminations, resins and Scotch electrical tapes – we stock high voltage cable joints and terminations manufactured from 3M using Cold Shrink for 11kV and 33kV cables.

Thorne & Derrick provide competitive prices and fast delivery from stock for the complete range of 3M Scotchcast and Cold Shrink cable joints, terminations, resins and Scotch electrical tapes – we stock high voltage cable joints and terminations manufactured from 3M using Cold Shrink for 11kV and 33kV cables.

LV, MV & HV Jointing, Earthing, Substation & Electrical Eqpt

Thorne & Derrick International are specialist distributors of LV, MV & HV Cable Installation, Jointing, Duct Sealing, Substation & Electrical Equipment – servicing UK and global businesses involved in cable installations, cable jointing, substation, overhead line and electrical construction at LV, 11kV, 33kV and EHV.