The Benefits of Partial Discharge Monitoring

Ben Jones Site Electrical Services Superintendent 5th November, 2015

Introduction

Ben Jones – Site Electrical Services Superintendent OneSteel Newcastle – A division of Arrium Mining & Materials Commenced working career on the Newcastle site for BHP in

1997 Have been responsible for the Newcastle High Voltage Network

since 2004

2000 – New company Onesteel from the demerger of BHP - Steel 2005 – began exporting iron ore - Mining 2007 – acquired Smorgon Steel & Recycling business 2010 – purchase of Moly-Cop – Mining Consumables

2012 – changed name to ARRIUM Mining and Materials to reflect our diversity into Mining

Partial Discharge (PD) is a localised dielectric breakdown of a small portion of the electrical insulation system under high voltage stress, which does not completely bridge the space between two conductors.

What is Partial Discharge (PD)?

PD usually begins within voids, cracks, or

inclusions within a solid dielectric, in bubbles within liquid dielectrics or with the ionisation of air around a high voltage conductor commonly referred to as Corona.

Internal Discharge

PD spark occurs within the voids due to the dielectric constant of the void being lower than the

insulation. As the voltage across the void exceeds the Corona Inception Voltage PD occurs.

Surface Discharge Corona Discharge is an electrical discharge brought on by the ionisation of air surrounding a High Voltage conductor due to the intensity of the magnetic field.

Accelerated HV Breakdown Test

What does PD do? Besides creating light, audible noise and ozone gas it can also: Generate ultra violet radiation which will degrade fibres and polymers such as

polypropylene and polyethylene. Ionises the air around conductors Create nitric oxide and in the presence of moisture nitric acid which oxidises

surrounding exposed metals. Cause progressive deterioration of insulating materials, ultimately leading to

electrical breakdown.

Arrium Major HV Failure Data 2007>2010

• Average 3 failures per year • Costing on average $5M per

failure

11kV High Voltage Failure of YSF6 Yorkshire Switch Board

22kV High Voltage Termination Box Failure

33kV High Voltage Sefton Termination Box Failure

Each of the above failures resulted in days of limited or no production capacity. Costs quickly escalated in some cases to millions of dollars when lost production and repair costs were calculated.

Luckily none of the above events resulted in personal injury but we

must not forget the potential for such an occurrence to cause serious harm or even death.

Impact

Locating Partial Discharge

The emissions generated by Partial Discharge allows it to be to be located by the use of a sensitive listening device such as the UltraTEV Plus.

This instrument is used to test for Transient Earth Voltages (TEV) and Ultrasonic signals emanating from discharge occurring within the High Voltage asset.

PD can be detected reliably in HV systems >4.1kV This method of condition monitoring can be completed safely with

the equipment energised and without the need to remove any covers exposing potential shock or arc fault hazards to technicians.

Partial Discharge Severity

TEV’s are induced voltage spikes on the surfaces of the surrounding metalwork of high voltage assets. The resulting readings are directly proportional to the condition of the insulation.

For Ultrasonic detection dB is

used to determine severity.

Successful PD Detections • PD detected using contact

probe on the external surface of the 33kV

termination box.

• Opening box found a large amount of condensation and formulation of white

powder on the termination creepage extension sheds.

Successful PD Detections

• PD detected using contact probe on the external surface of the 33kV termination box.

• Opening box found

breakdown of the termination kits where insufficient air gap between conductors was maintained.

• PD detected using the extension microphone in

and around an 11kV circuit breaker.

• Discharge was occurring

between two covers protecting the live

terminations underneath.

Successful PD Detections

• PD detected using the extension microphone in and around an 11kV circuit breaker.

• Discharge was occurring between the connecting cluster and outer insulating spouts.

Successful PD Detections

Successful PD Detections PD detected using the

ultrasonic probe attached to the outside of the 11kV

termination box enclosure

Successful PD Detections PD detected using the ultrasonic

probe attached to the outside 11kV termination box enclosure.

• PD detected using contact probe on the external surface of the 33kV termination box.

• Opening box found

breakdown of the termination kits where insufficient air gap between conductors was maintained.

Successful PD Detections

Thank You