Partial Discharge Detection Products by EA Technology

Instruments Overview

EATL History & Values• Originally established as R&D center for the UK Electricity Industry

• Provides research, strategic engineering consultancy, HV asset

condition assessment services, specialized instrumentation

• Operating for over 40 years

• 100% employee owned

• Our mission is to deliver:

•Tangible benefits

•Demonstrate clear added values

•Achieve customer objectives

We focus on enhancing our customers’ profitability

People• Over 150 technical experts engaged in consultancy & high level

technical services

• Staff are experienced at providing technical solutions to owners &

operators of power networks worldwide

• World leading specialists in power asset management and equipment

failure related to partial discharge

• 40 years of technical know how in power networks

Unrivalled intellectual excellence to engineering

solutions

Products & ServicesProducts

• Substation Condition Monitoring equipment

• Fault location & diagnostic instruments

• Asset management software

Services

• Condition Assessment of overhead lines and towers

• Power skills training

• Forensic failure investigation

EA Technology innovations become industry standard

Corporate StructureGroup

Management

EA Technology

LLC USA

EA Technology

Limited (UK)

Group

Operations

Development

Manufacturing

Finance/Support

Sales &

Marketing

Europe

Operations

Asset

Management

Future Networks

Technology

Middle East

EA Technology

Australia

EA Technology

Singapore

EA Technology

Shanghai

EA Technology LLC• Located in Denville, New Jersey (35 mi west of NYC)

• Focused on providing high quality Instruments, Services,

and Consulting to electrical power industry and private

network owners.

• Provides local stock, support, & calibration

• Over 50 years experience in the electrical power industry.

• Working with a network of Manufacturer’s Representatives,

Service Partners and Rental Partners.

Partial Discharge (PD) the key to OUTAGE PREVENTION

Partial Discharge (PD)the key to OUTAGE PREVENTION

BECAUSE PD is a factor in 85% of MV substation insulation failures

PD measurement BUSINESS BENEFITS

• Outage prevention

• Improved reliability and safety

• Reduced maintenance costs

• Smarter replacement decisions

PD failure process

• Multiple causes

• Starts small

• ALWAYS gets worse

• Leads to FLASHOVER

• Occurs at voltage peaks

• Caused by field strengths in excess of insulation

withstand capability


switchgear failure switchyard failure


Partial Discharge - A flashover of part of the insulation system due to a localized electric field greater than the dielectric withstand capability of that part where the overall insulation system remains capable of withstanding the applied electrical field.

Void

GroundConductor

V withstand of C2 < applied field V withstand of C1&C3 > applied field

What is Partial Discharge (PD)?

11

One effect of this flashover is a high frequency current pulse that travels through the capacitance of the insulation (C1 & C3)

HF CurrentPulse

C1 C2 C3

Products of Partial Discharge

12

Partial discharge breakdown of insulation produces:

Light, Heat, Smell, Sound, Electromagnetic Waves, and an

HF Electric Current

+

Water

Nitric

AcidElectric

TEV

Partial Discharge (PD)

• 3.3kV to 69kV

• Indoor Metal clad switchgear cubicles

• Indoor and Outdoor Insulators

• Transformer Cable Boxes

Types of Switchgear

the key to OUTAGE PREVENTION

Types of PD

•Internal discharges occurring in defects, voids or cavities within solid insulation

•Surface discharges occurring across the insulation surface

Corona discharge occurring in gaseous dielectrics in the presence of inhomogeneous fields

internal PD

Occurs in all types of insulation, including oil and gas


Surface PD

Causes treeing and tracking


Practical Non-Intrusive Detection Methods

Internal discharge activity • Transient Earth Voltage (TEV) Detection

Surface discharge activity• Ultrasonic Emission• TEV Detection - when high amplitude surface

discharge

INTERNAL DISCHARGETEV Detection

Internal Partial Discharge Effect 1(current pulse - TEV)

19

HV BUSBAR

PARTIAL DISCHARGEJOINT/GASKET

HV BUSBAR

HIGH FREQUENCY

PULSE TO METALWORK VIA

CAPACITANCE OF INSULATOR

PULSE TRAVELS

VIA SKIN EFFECT

TEV RESULTS DUE TO

IMPEDANCE OF GROUNDING

At HF, PD currents are constrained to

Flow in a thin layer on the surface of

Conductor.

Skin depth in mild steel at 100MHz

0.5um

Internal Partial Discharge Effect 1(current pulse - TEV)

20

HV BUSBAR


HV BUSBAR

HIGH FREQUENCY

PULSE TO METALWORK VIA

CAPACITANCE OF INSULATOR

TEV RESULTS DUE TO


At HF, PD currents are constrained to

Flow in a thin layer on the surface of

Conductor.

Skin depth in mild steel at 100MHz

0.5um

UltraTEV

PULSE TRAVELS

VIA SKIN EFFECT

HV BUSBAR

EM WAVEEM

WAVE


HV BUSBAR

21

Internal Partial Discharge Effect 2(EM Wave)

PULSE TRAVELS

VIA SKIN EFFECT

TEV RESULTS DUE TO


This effect is usually less than the

current pulse unless the PD is

phase to phase!

UltraTEV

Phase to Phase Partial Discharge (current pulse – NO TEV)

22

HV BUSBAR


HV BUSBAR – Phase A

HIGH FREQUENCY

PULSE FROM PHASE TO ANOTHER.

NO CURRENT PULSE

ON METALWORK

No TEV reading

UltraTEV

HV BUSBAR – Phase B

HV BUSBAR – Phase C

23

Internal Partial Discharge Overhead insulator (TEV)

PULSE TRAVELS

VIA SKIN EFFECT

TEV RESULTS DUE TO


Insulator

Discharge

Conductor

UltraTEV

24

Internal Partial Discharge Overhead insulator (EM Wave)

EM Wave

PD Hawk

TEV from PDEMI from PD

Corona

PD Hawk

PD Spectrum (Simplified)

• Partial Discharge

causes a broadband EMI

emission

(approx. 3-3000 MHz)

• Corona causes a smaller

band EMI emission (30-

400 MHz)

• TEV caused by

capacitive currents are

typically in the

3-80 MHz band

• PD Hawk is typically set

to approx. 800 MHz

26

Probable Internal

No Internal Significant

Discharging

PossibleSurface Discharging

ProbableBackgroundInterference

Probable Floating Metal

Bad Conn

TEV Interpretation

27

Background level

Above 10 dB Below 10 dB

Eliminate Background where possible and continue

TEV Level on switchgear

Within 10 dBof Background

More than 10 dBAbove background

No significantInternal Discharging

Pulses per cycle

Above 150 PPC1-50 PPC

ProbableInterference


Pulses per cycle

More than 50 dB

Below 25

ProbableBad Connection

ProbableFloating Metal

Around 100 8-150 PPC


< 20 dB > 20 dB

Probable internal Discharge

< 10 dB

No significant InternalDischarging

10 - 45 dB

Probable Surface Dischargeconfirm with Ultrasonic

Above 150 PPC

Example 1: Failure of Cast Resin CT

Long term erosion of

insulation leading to

flashover and failure

Cable Termination Screen Failure

Background Interference

A B C D E F

Battery

charger

Radio

mast

DC Light fitting

Mobile

phone

mast

HV OHL

Variable

speed

drive

Switchboard

Surface Discharge - Ultrasonic Detection

Sound Emission

In severe cases, sound may be audible

Less severe deterioration may be detected using ultrasonic detecting instruments

Sound spectrum in the 40kHz range

Characteristic sound more important than absolute level

Cracks / contaminated surface

Carbonised tracking

Discharge noise can be picked up

with Ultrasonic detector via gap

• Measurement relies on an air path

out of the switchgear

• Types of access

– Cable box vents

– CB Bushings / HV spouts

– Gaps around panel joints

– Bolt holes

Contact probe

Designed to work though cabinet

metalwork, no direct air path needed

Surface Discharge

Environmental Factors

• Moisture in air will play a significant role in whether discharge is active

• When monitoring ultrasonically the environmental conditions (%RH and Temperature) should also be monitored

0

10

20

30

40

50

60

70

80

90

100

29/03/2005

00:00

03/04/2005

00:00

08/04/2005

00:00

13/04/2005

00:00

18/04/2005

00:00

23/04/2005

00:00

28/04/2005

00:00

03/05/2005

00:00

08/05/2005

00:00

13/05/2005

00:00

Date

%R

H, T

emp

erat

ure

0

1

2

3

4

5

6

7

8

9

10

Lev

el o

f U

ltra

son

ic A

ctiv

ity

°C %RH Ultrasonic

Ultrasonic Survey (Practical Considerations)

• Influenced by environment (e.g. temperature, humidity, pollution).

• Discharge has a distinctive crackling noise.

• Often intermittent, particularly during early stages.

• Severity of discharge is not necessarily related to noise amplitude.

Possible Ultrasonic Background Interference

•Vibration from switchgear panels

•Normal transformer ‘hum’

•Noise from adjacent plant and machinery

•Very high EM PD activity

•Corona from HV OHLs

•Electronic interference from light fittings

•Battery chargers and DC panels

•Rustling of clothes e.g. waterproof coat

•Other people in substation

Surface Discharge Activity Detected by Ultrasonics

Surface Discharge Activity

•Discharge across surface of

insulation towards earth or

phase to phase discharge

•Often characterised by low

amplitude but very high

discharge rate

Moisture Ingress leading to surface tracking

Surface Discharge on 11kV Cast Resin Circuit Breaker Spouts

Surface Discharge Activity Detected by Ultrasonics

11kV CB Porcelain Spout

Fixed HV spout

(Porcelain)

CB Bushing (Resin)Film of sticky petroleum jelly

Remedial Action

Cleaned Off with dry lint free

wipes

Raychem

Sleeve

2mm

Crossed

Remedial Action

Replace the last

few metres of the

cable by putting in

a new joint

and termination

•Corrosion as a result of PD activity

•PD activity forms nitrous oxide gases

•In the presence of moisture can produce nitric oxide and a very corrosive environment

Corrosion due to PD activity

Surface Discharge and Internal

Discharge Differences

Internal PD External PD

Not affected by Humidity Affected by Humidity

0.5-8 Pulses per Cycle 8-30 Pulses per Cycle

Rarely Audible Often Audible

Detected best by TEV Detected best by Ultrasonic

Thin Double Spike on PD Hawk

Wide Double Spike on PD Hawk

Hold UltraTEV against metalwork

Hold UltraTEV at airgaps

Partial Discharge and Transformers!!!!!

The ultraTEV line is particularly suited to finding PD in cable boxes, insulators, and bushings on transformers.

The PD Hawk is well suited to finding PD in exposed insulators and bushings on large transformers.

TEV inside the oil filled cavity is not typically detectable due to:• Most PD in transformers occurs between windings which does

not generate TEV

Ultrasonic detection (ours and competitors) inside the oil filled cavity is of limited use because:• The oil significantly dampens ultrasonic noise• The transformer hum overwhelms most other signal sources

Partial Discharge and Transformers!!!!!

Acoustic emission detection systems do exist and can detect and localize PD in large oil filled transformers but:

• They are hugely expensive and complicated to operate• They are only applicable to large oil filled transformers• Our instrument line is complementary to those devices as

they can’t do what the UltraTEV and PD Hawk can do.

Dissolved gas analysis is still the most accepted way of determining the health of large transformers


Detect

PD Techniques

surface/airgap: ultrasonic

internal: TEV

IDEAL FOR first pass surveys of surface and internal PD activity

UltraTEV Detector™

dual-sensor PD detection tool

TRAFFIC LIGHT display indicates PD levels


internal: TEV



ESSENTIAL personal safety device:

warns of dangerous PD activity in

working environment

substation entry working in substations



complete kit

• Easy to use

• Portable

• Rugged

features

• Fast

• Factory-calibrated for

accuracy

• Minimal training need




MEASURE

PD techniques

•Built on the knowledge and experience of

over 30 years of PD testing

•Menu driven backlit color LCD screen and

keypad

•Long-life rechargeable Li-Ion battery

•Lightweight, tough, ergonomically

designed

UltraTEV Plus+™

multi-functional Partial Discharge (PD) instrument

Provides two techniques to QUICKLY locate & measure surface and internal PD activity


internal: TEV

UltraTEV Plus+™

multi-functional Partial Discharge (PD) instrument

TEV Measurements

•Measurement of internal TEV activity in range 0 – 60dBmV

•Two measurement modes

– Continuous

– Single Shot

•User adjustable alarm thresholds

•Traffic Lights default UltraTEV Detector levels

•50/60Hz adjustable system frequency

TEV Functions

•Two TEV display options

•Display with rolling bar graph indication and traffic light alarm level indication

•Display with amplitude, pulses per cycle and severity values

Ultrasonic Measurements

•Measurement of surface discharge activity in range

– -7dBµV to 68 dBµV

•Hetrodyned audible output with high quality headphones

•External ultrasonic sensor port

•User adjustable alarm thresholds

– Preset to UltraTEV Detector levels

Ultrasonic Features

•Separately adjustable Gain and

Volume settings

•Immediate Red / Green

indication based on user

adjustable alarm threshold

Ultrasonic Optional Accessories

•Optional external flexible microphone to extend reach

•Optional external parabolic dish for surveying of overhead assets

•Contact microphone for use when no air path is available


PD techniques

SURVEYS & LOCATES PD activity in all substation assets – including cables

surveys locates

UltraTEV Locator™

portable Partial Discharge (PD) investigation system

MEASURES & RECORDS PD activity in all substation assets – including cables

measures records

UltraTEV Locator™


PLUG-IN OPTIONS for greater versatility

RFCT cable sensor Ultrasonic Contact ProbeTM

UltraTEV Locator™


features

• Locates PD source to

<10cm (<4”)

• Measures & records PD in all

substation assets

• Minimal training need

UltraTEV Locator™


UltraTEV Locator™


complete kit

• Easy to use

• Portable

• Rugged

UltraTEV Locator™


7

1

• A Cable Testing System that detects Partial Discharge activity in live MV cables

• Easy to use, portable and rugged solution for determining cable condition

• Can be used on Single Phase or Three Phase cables

• Requires little training and no PD expertise to collect data

Cable Data Collector™

Partial Discharge (PD) detection in cables

72

How It Works



7

3

• The CableData™ Collector is a Cable Testing System that detects and measures Partial Discharge activity in live medium voltage (3.3KV to 69KV) cables

• Provides quick, safe and non-disruptive testing

• Uses Radio Frequency Current Transformers (RFCT) to measure radio frequency currents produced along the cable

• Can be used on Single Phase or Three Phase insulated cables up to several kilometres in length (maximum length varies and is determined by background noise, size of discharge and cable type)



7

4

• Designed to be small, portable and rugged to withstand to rigors of use in industrial environments

• Connects to a laptop running the CableData™ Collector software allowing data to be captured quickly and easily and for it to be stored for offline analysis using CableData™ Analysis Software

• Plug and Play – plug it in and start working!

• CableData™ Analysis Software allows offline analysis of captured data and producing of reports summarizing any activity discovered during testing



7

5

•The CableData™ Collector Solution consists of three components

• CableData™ Collector Instrument (left image)

• CableData™ Collector Software (center image)

• CableData™ Analysis Software (CDAS) (right image)



76

CableData™ Collector Solution -Hardware• Powered and controlled from a USB port on

laptop/netbook

• Four channels of dedicated high speed, wide dynamic range analogue input allowing simultaneous acquisition giving cleaner signals and better analysis output

• Variable gain blocks on each channel to allow detection of both small and large amplitude signals

• Sophisticated Digital Signal Processing and Filtering to allow PD to be detected even when obscured by large levels of noises – no external filters and no knowledge required

77

CableData™ Collector Solution –Cable Data Analysis Software (CDAS)

• Application to import and display data collected using a CableData™ Collector instrument

• Displays Waveform and Phase Resolve Event data on interactive charts

• Provides the ability to map discharge activity along cable length

• Allows condition reports to be created using the imported data

• Captured data analysed on software suite

• Allows classification and analysis of cable PD data

• Retrospectively see the effects of different filters

• Identify local discharge and discharge down cable

78

Powerful data analysis



79

Collecting Data

Collecting data is quick and easy:

1. Clip the RFCTs around the earth straps of the cables to test and connect to the instrument using BNC cables

2. Connect the Phase Reference Transformer to the CableData™ Collector

3. Connect the CableData™ Collector to the laptop and launch the CableData™ Collector Software

4. Enter asset details about the cable under test and click the Start button. Data is captured and stored with no intervention required

SAFELY locates internal PD activity in open terminal switchgear

PD Emission

PD Hawk™

switchyard PD locator

How it works

• Narrowband radio receiver (10 MHz)

• Phased antenna array provides directionality

(45 degree cone)

• Tunable center frequency (avoid interference)

• Usually tuned to 800 MHz (ignores corona)

• RF demodulator moves sound to audio range

(use headphones for discrimination)

• Built in Spectrum Analyzer function

Lithium Ion

Battery

Speaker

Display and

controls

PD Hawk™


business benefits

• Prevents costly failures

• Rapid return on investment

• Gathers valuable data on

asset condition

• Extends asset life

PD Hawk™


Directionality

• Design causes off center signals to

be attenuated

• Signals closest to center detected

strongest

• Directionality up-down and left-right

• Rotate instrument 90 degrees to

account for polarization

SignalsdetectedIn this range

Signals out hereare rejected

Signals out hereare rejected

PD Hawk™


Sweep the Hawk around substation while rotating 90 degrees to compensate for polarization

PD Hawk™


Safely approach the locations with highest levels and aim at specific assets

PD Hawk™


Record or download data for reporting or comparison with future readings

Android Tablet/Phone App

PD Hawk™


complete kit

• Easy to use

• Portable

• Rugged

PD Hawk™



PD techniques

24/7 MONITORING of substation assets

• Detection

• Location

• Measurement

• Recording

• Communication

• Alarms

• Analysis

• Interpretation

• Reports

UltraTEV Monitor™

substation monitoring and alarm system

UltraTEV Monitor

UltraTEV Monitor

1.High precedence resolution and dynamic range (1ns, 12 inches)

2.Can support up to 250 TEV measuring points

3.Detailed coverage, every channel of every node is monitored independently and continuously. No multiplexing between channels and no lost data.

4.Ultrasonic sensors improve coverage for surface discharges, two per node.

5.Cable PD measurement via dedicated CT inputs. This includes magnitude measurement, waveform capture and precedence for PD location.

6.Contact probe for switchgear temperature measurement at each system node.

Example Node

Power &

Status LEDs

Ultraso

nic

Inputs

Cable

PD

Input

TEV

Input

Aux

Power

Input

Communications

Test and Reset

Buttons

Sensor Status

LEDs

Example Sensors

External TEVSensor

Antenna (for cancelling background noise)

EnvironmentalSensor

UltrasonicSensor

Single Discharge Site

– Neither precedence or magnitude alone provide a good indication of location and severity of discharge

– Precedence is very good for location

– Magnitude when combined with precedence gives a good measure of severity

– Magnitude and precedence measured on a pulse by pulse basis.

– Allows magnitude profile for each source to be isolated providing improved measurement accuracy.

– 1ns precedence resolution gives exceptional location accuracy.

Severit

y

Magnitude Source A

Precedence Source A Precedence Source B

Magnitude Source B

Single Discharge Sites

96

Instance Profile – Data Selection

97

Select Monitoring Time Period

Select the generated period

Summary Report

98

Summary Report

Thank you

Call +1 862 261 2759 or Email [email protected]

For further information

Date post:	08-Jul-2015
Category:	Technology
Upload:	ryan-mcfallo
View:	630 times
Download:	12 times