Tommy Roes

Business Unit Manager - UDT

Martec

South Africa

Predictive Maintenance for

Metal Clad MV Switchgear

Introduction

1. Risk

Death / Injury

Unscheduled Downtime

Loss of Electrical Assets

Environmental impact

2. Focused on “Win Win”

3. PPE

4. Other preventative measures

Introduction

What are the Issues

Cause vs. Symptoms

A Proactive Approach

The Technologies

Understanding the Limitations

Examples

Case Studies

What are the Issues ?

New Installations

Aged Installations

Unpredictable events

Ignorance

Arc Suit

External operation (switching) ?

Last Line of Defense

First Line of Defense

Safety Mindset

Detection Tools

Play a dual role

Electrical Faults

%

Insulation Failure 95 90 84 53 7

Mechanical Failure 5 0 4 36 23

Other Failure 0 10 12 11 70

<12 Months since last maintained 10 25 34 22 58

12-24 Months since last maintained 35 45 38 57 42

>24 Months since last maintained 55 10 22 19 0

No PM 0 20 5 2 0

Considering all failures on average 8% to 23% Age Related

77% to 92% Other reason

Switchgear

Bus Duct

Transformers

Motors

Generators

Source: IEEE Std. 493-1997 (Gold Book)

Electrical Faults

80% NOT due to ageing

Water Ingress

Cracked Insulators

Poor Installations

Partial Discharge (Corona)

Partial Arcing

Tracking and Arcing

Common Defects

Corona

Partial Discharge

Ionisation of the air molecules at locations of

high stress

Produces corrosive gases Ozone and Nitrous

Oxides

Is influenced by humidity levels

Tracking

Flow of electricity over a Interface of dissimilar

materials, insulator/air, insulation/conductive

tapes.

Must have a path to aid in its development

Constant build up and release of energy

Arcing

Flow of electricity from one conductor to another

Results in the rapid destruction of all connected

equipment

Rapid expansion of Gas

Causes fires and explosions

Extremely violent

Generates extreme temperatures

A Proactive Approach

Understanding

Being Proactive

Surveys and Inspections

Taking precautionary measures

PPE

Explosion containment panels

Explosion vents

Training

Combining a basket of Tools

Thermography (Infra-Red)

Indicates a “hot spot” in relation to those around

it.

Detects radiant energy

Line of sight

Surface measurement

Advantages

Easy to relate

Goes with our natural senses (seeing is

believing)

Comparable

Accurate

Exclusively used for poor connections

Training (Don’t believe everything you see)

Thermography (Infra-Red)

Ultrasound

Beyond the Range of Human Hearing

Generally any sound signal above 20kHz

Travel through Gases, Solids and Liquids

Travels in a very Directional Nature

Low Energy Signal

“Listen” to it

Measurable

Recordable

Scalable

Ultrasound

Advantages

Easy, quick and accurate

Can measure, record and analyse for severity

Scalable

Does not require “line of sight”

Great for closed, Live switchgear

Great for Bushings

Radio Frequency

Radio Frequency signals

(Electro magnetic radiation)

Radio Frequency

Advantages

Detects fast transients

Detects the presence of all defects

Can be used in substations or on overhead lines

Fast “indication” technique

TEV (Transient Earth Voltages)

PD within MV/HV equipment induces a voltage

on the inner surface of switchgear cubicles and

panels.

TEV (Transient Earth Voltages)

Advantages

Measurable for amplitude

Comparable

Trend able

Electrical measurement and analysis of radio

frequency cable insulation ageing signals which

are emitted from the cable whilst it is in normal

service.

Online Condition Assessment

Online Cable Assessment

Advantages

Detailed Diagnostic and Prognostics

The Signs and Signals

Partial Discharge

Smelly Gas (Ozone)

White powdery deposits

Generates Ultrasound

Generates Electromagnetic radiation

Radio Frequency

UV

TEV

Does NOT generate radiated heat

The Signs and Signals

Arcing

Generates Ultrasound

Does generate Heat

Generates Electromagnetic radiation

Radio Frequency

UV

TEV

Generates large quantities of UV

Detection Methods - Legend

Technology Corona Tracking Arcing

Infra-Red •

Ultrasound • • •

Radio Frequency • • •

TEV • •

UV • •

Cable Assessment • • •

Understanding the Limitations

Technology Limitations

Infra-Red Line of Sight, Advanced stage defects, Defects generating heat

Ultrasound Limited to accessible signals

Radio Frequency Multiple RF sources, diagnosis not possible

TEV Minimal diagnostic abilities, multiple sources

UV Line of sight

Cable Assessment Not portable, requires a specialist service provider

Partial Discharge - Corona

Tracking

Tracking on 22kV overhead

Arcing

Arcing can be identified

An “abrupt start and stop”

Case Study 1

Partial Arcing

Case Study 2

Tracking on Terminations and Joints

Live Demonstration

PD demo

Presentation guidelines

Speakers should try not to exceed 24 slides per

25 minute presentation (Roughly one slide per 1

or 2 minutes of talk and 5 minutes for questions.)

Do not forget to bring a copy of your

presentation with you on the day!

Short phrases, not long sentences.

Presentation guidelines

Use Arial or similar font, try keep font at 28

points or larger and no smaller than 20 points so

people in the back of the conference room can

read your slides.

Titles should be 33 points or larger.

Do not use sound effects, they slow down

slide transitions and the noise from projection

computer may distract audience.

Presentation guidelines

Rather use video clips if sound and recordings

are required for your presentation. Please

discuss this with the organizers so that

arrangements can be made to accommodate

your request.

Presentation guidelines

Please do not number your slides

Each slide should have a title

9 lines max on a text slide

Maximum 10 words per line

Caution: Red, orange or yellow lettering and

lines become unreadable when projected.

Presentation guidelines

Watch out for:

Wingdings.

MS line draw.

Monotype sorts.

Scientific symbol fonts.

Asian language fonts.

Can embed TrueType fonts in file.

Presentation guidelines

Use of pictures, graphics, tables, etc. is at the

discretion of the speaker:

Keep diagrams simple and easy to view

Make text readable with large font

Use all space in rectangle

Make sure your presentation is readable when

printed in black and white

Presentation guidelines

Branded or company logos are only permitted on the opening slide.

Logos (other than that of the event logo) may not be used throughout the presentation, unless prior authorization has been obtained from the organizers.

Presentation guidelines

Deadline for submission of presentation for

the proceedings: 12 April 2013

Please ensure that you bring a copy of your

power-point slides with you on a memory stick

the day of your presentation. If you change your

slides please email the organizers asap with the

updated copy.

Presentation guidelines

For any additional information, please do not

hesitate to contact Nicolette Pombo-van Zyl:

Email: nicolette.pombo-vanzyl@spintelligent.com

Phone: +27 21 700 3554

Mobile: +27 83 344 3198

Spintelligent (Pty) Ltd

Phone: +27 21 700 3500

Fax: +27 21 700 3501