TERMINATING THEORY & PRODUCTS

cause serious injury or death. Installation should be performed by personnel familiar with good safety practice in handling high voltage electrical equipment. De-energize and ground all electrical systems before installing product.

Caution: Working around energized high-voltage systems may

TERMINATING THEORY & PRODUCTS

CLASS 1 TERMINATION(IEEE Standard 48)

• Electric Stress Control for the Cable Shield Terminus

• External Leakage Insulation between H.V. Conductor and Ground (Tracking Protection)

• A Seal to the External Environment

I. STRESS CONTROL

Semi-conducting Shield Layer

For the Cable Shield Terminus

NO STRESS CONTROL

TraditionalGEOMETRIC STRESS CONE

DIELECTRIC (HIGH-K) STRESS CONTROL

High-K (high dielectric constant) material is used to reduce stress at the shield discontinuity by field refraction due to different K values of two adjacent dielectric layers.

HI-K STRESS CONTROL

EXAMPLE: Snell’s Law of Refraction

TRADITIONALSTRESS CONE

TERMINATION

HIGH-KSTRESS CONTROLTERMINATION

II. EXTERNAL LEAKAGE INSULATIONBetween Conductor & Ground

THEINSULATOR

FLASHOVER PROTECTION TRACKING PROTECTION

BIL per (IEEE 48)

TRACKING

• MOISTURE- Humidity- Fog- Condensation- Mist- Snow- Rain

• CONTAMINATION- Dust- Chemicals- Salt- Other Airborne Particles

• VOLTAGE- Surface Stress (V/mil)

Three Conditions Must Exist:

DISCHARGE FORMATION Surface Resistance

Reduced When Wet

DRY BANDS

ELECTRICAL DISCHARGES

(Generated in Dry Band Areas)

(Areas of Higher Surface Resistance)

&Concentrated

Voltage Gradient

Ways To CONTROL TRACKING

3. Track Resistant Materials- Porcelain

- Silicone Rubber- Inorganic Fillers in EVA (Heat Shrink)- Inorganic Fillers in Rubber

2. Rain Shed (Insulator Skirts)

1. Increase Distance from HV to Ground

Advantages of Silicone Rubber as INSULATOR MATERIAL

4. Silicone is Mostly Inorganic -- (No Conducting Carbon Path)

3. Silicone is Inherently UV-Stable

2. Silicone Can Recover Its Hydrophobicity

1. Silicone is Hydrophobic

5. Silicone Has a Smooth Surface

ExamplesHYDROPHOBIC & HYDROPHILICSILICONE RUBBER PORCELAIN

Hydrophilic(Surface “Wets”)

Hydrophobic(Water “Balls-up”)

HYDROPHOBICVS

HYDROPHILIC

HYDROPHOBIC HYDROPHILIC

Contact Angle

Energy from leakage current can cause insulator surfaces to become hydrophilic

Water “balls” up Surface “wets” out

Recovery of Contact Angle for SILICONE RUBBER TERMINATIONS

Recovery of Contact Angle

24 Hrs. (Recovered)

90 Deg. Recovery

(Based on study performed in cooperation with Arizona State University)

SILICONE RUBBER INSULATORCoated with ASTM D-2132 Contaminant

Surface remains “Hydrophobic”

EPDM INSULATOR

UV Damage

SUMMARY and CONCLUSIONS

• Silicone Insulators are superior to EPDM, EVA and porcelain insulators

• Silicone is more hydrophobic than other polymers or porcelain

• Silicone has the ability to regenerate its hydrophobicity in the event that high-leakage current changes its state

• Silicone Insulators are inherently stable to UV due to its high backbone bond energy

• 3M™ Silicone Rubber Terminations - In use 30+ years with excellent results

III. SEAL

To the External Environment

Top Seal

Bottom Seal

PottingCompound(Conductor Seal)

(Jacket Seal)

SEALINGwith

TAPE

POTTINGwith

RESIN

SEALINGwith

HEAT SHRINK

SEALINGwith

COLD SHRINK

HEAT SHRINK TERMINATION

Example ofHEAT SHRINK TERMINATION

Raychem HVT

Heat Shrink TerminationINSTALLATION

(2)

Stress ControlTube

(1)

Stress Relief Material

(Semi-con StepFiller)

(Special Torch,“Bushy” Flame)

(4)

Jacket Seal

(3)

Top Seal

(6)SeparateInsulator

Skirts

(5) Separate Insulator

TubeAllow Tube

To CoolBefore

ProceedingShrinkEvenly

With no Tilt or Sag

COMPLETEDTERMINATION(S)

Outdoor Termination(with skirts)

Indoor Termination(same, but without skirts)

COLD SHRINK TERMINATION

Examples of Silicone RubberCOLD SHRINK TERMINATIONS

Joslyn JPT & Plymouth/Bishop ColdTerm

3M™ QT-II Termination 3M™ QT-III Termination

Plymouth JoslynSiliconeTape Top Seal

SiliconeTape Top Seal

Pull Tabs

Integrated 1-Piece

SiliconeGrease Silicone

Grease

Examples of Silicone RubberCOLD APPLIED (Shrink) TERMINATIONS

Raychem TFT

Twist & slide off of holdout tube onto cable

“Holdout” Tube

Adjust into final position if necessary

Use pull tabs to position over jacket

VITAL STEP: Loosentermination by twistinguntil it moves on holdout

Typical Cold Shrink TerminationINSTALLATION

Apply mastic seal around jacket& neutral wires

Apply siliconegrease to fillsemi-con step

Install terminationby removing supporting core

Complete top sealwith applicationof silicone rubber tape

COMPLETEDTERMINATION(S)

Outdoor Termination(With Skirts)

Indoor Termination(Tubular, without Skirts)

BENEFITS of COLD SHRINK

• Environmentally Stable Materials

• Broad Application Range

• Live Seal

• Good Interfacial Pressure

• Low Installation Force

• No Tools for Installation

INTRODUCING: 3M™ QT-III Termination

IMPROVED SILICONE RUBBER Cold Shrink Termination

• SMALLER SIZE - Easier mounting

• IMPROVED HIGH-K STRESS CONTROL - Improved corona, 60 Hz and impulse withstand performances

• BUILT-IN SEMI-CON FILLER - No silicone grease

• BUILT-IN TOP SEAL - Eliminates taping of top seal

• IMPROVED SILICONE RUBBER - Improved Tracking Resistance

3M™ QT-III Termination Integrated 1-Piece Design

Silicone Sealing Compound

High Dielectric ConstantStress Relief Tube

Stress ControlCompound

Step Core

Silicone RubberInsulator

SIZE COMPARISON: 15 KV CLASS

- Shorter cable prep distance

- Accommodates smaller space in cabinets

- More versatile for mounting

3M ™ QT- II Termination

3M ™ QT- III Termination

INVERTED 3M™ QT-III Outdoor Termination

• SILICONE SEALING COMPOUND No (inverted) bottom seal taping required

Eliminates silicone grease at semi-con cut-back step

• HI-K SEALING COMPOUND

BUILT-IN COMPOUNDS:

SUMMARY

“TECHNOLOGY AND THE HUMAN FACTOR”

• Cold Shrink Design for Easier Field Installation

• Factory Assembled Quality - Reliability

• Integrated 1-piece Designs

• New Developments in Sealing Compounds

• New Developments in Silicone Rubber Technology

This New Generation of Polymeric Terminations Takes Advantage of:

Install 3M ™ QT-III Termination

TERMINATION WORKSHOP