Partial Discharge Detection Products by EA Technology

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 & Services
Products
• 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 Structure
Group
Management
EA Technology
LLC USA
EA Technology
Limited (UK)
Group
Operations
Development
Manufacturing
Finance/Support
Sales &
Marketing
Technology
Middle East
Europe
Operations
Asset
Management
Future Networks
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

PD measurement BUSINESS BENEFITS
• Outage prevention
• Improved reliability and safety
• Reduced maintenance costs
• Smarter replacement decisions
BECAUSE
PD is a factor in 85% of MV substation insulation
failures

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

What is Partial Discharge (PD)?
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.
HF Current
Pulse
C1 C2 C3
Conductor Ground
Void
V withstand of C2 < applied field
V withstand of C1&C3 > applied field
11
One effect of this flashover is a high frequency current pulse that travels through the
capacitance of the insulation (C1 & C3)

Products of Partial Discharge
1
2
Partial discharge breakdown of insulation produces:
Nitric
Acid
+
Water
Light, Heat, Smell, Sound, Electromagnetic Waves, and an
HF Electric Current
Electric
TEV

Types of Switchgear
• 3.3kV to 69kV
• Indoor Metal clad switchgear cubicles
• Indoor and Outdoor Insulators
• Transformer Cable Boxes

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 DISCHARGE
TEV Detection

Internal Partial Discharge Effect
1(current pulse - TEV)
1
9
PARTIAL DISCHARGE
HV BUSBAR
JOINT/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

1(current pulse - TEV)
2
0
PARTIAL DISCHARGE
HV BUSBAR
JOINT/GASKET
HV BUSBAR
HIGH FREQUENCY
PULSE TO METALWORK VIA
CAPACITANCE OF INSULATOR
PULSE TRAVELS
VIA SKIN EFFECT
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

PARTIAL DISCHARGE
HV BUSBAR
JOINT/GASKET
HV BUSBAR
EM EM WAVE
WAVE
2
1
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)
2
2
PARTIAL DISCHARGE
HV BUSBAR
JOINT/GASKET
HV BUSBAR – Phase A
HIGH FREQUENCY
PULSE FROM PHASE TO ANOTHER.
NO CURRENT PULSE
ON METALWORK
UltraTEV
No TEV reading
HV BUSBAR – Phase B
HV BUSBAR – Phase C

2
3
Internal Partial Discharge
Overhead insulator (TEV)
PULSE TRAVELS
VIA SKIN EFFECT
TEV RESULTS DUE TO
Insulator
Discharge
Conductor
UltraTEV

2
4
Internal Partial Discharge
Overhead insulator (EM Wave)
EM Wave
PD Hawk

TEV from PD
EMI 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

2
6
Probable
Background
Interference
Probable
Internal
No Internal
Significant
Discharging
Possible
Surface Discharging
Probable
Floating
Metal
Bad
Conn

TEV Interpretation
2
7
Background level
Above 10 dB Below 10 dB
Eliminate Background where
possible and continue
TEV Level
on switchgear
Within 10 dB
of Background
More than 10 dB
Above background
No significant
Internal
Discharging
Pulses per cycle
1-50 PPC Above 150 PPC
Above 150 PPC
8-150 Around 100
PPC
Probable
Interference
TEV Level
on switchgear
Pulses per cycle
More than 50 dB
Below 25
Probable
Bad
Connection
Probable
Floating
Metal
TEV Level
on switchgear
< 20 dB > 20 dB
Probable
internal
Discharge
< 10 dB
No
significant
Internal
Discharging
10 - 45 dB
Probable
Surface
Discharge
confirm
with
Ultrasonic

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
Surface Discharge
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

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
100
90
80
70
60
50
40
30
20
10
0
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
10
9
8
7
6
5
4
3
2
1
13/05/2005
00:00
Date
%RH, Temperature
0
Level of Ultrasonic Activity
°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

11kV CB Porcelain
Spout
Fixed HV spout
(Porcelain)
Film of sticky petroleum jelly CB Bushing (Resin)
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 due to PD activity
•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

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

UltraTEV Detector™
dual-sensor PD detection
tool
surface/airgap:
ultrasonic
internal: TEV
IDEAL FOR first pass surveys of
surface and internal PD activity

tool
surface/airgap:
ultrasonic
internal: TEV
TRAFFIC LIGHT display indicates PD
levels

tool
substation entry working in
substations
ESSENTIAL personal safety device:
warns of dangerous PD activity in
working environment

complete kit
• Easy to use
• Portable
• Rugged
tool
features
• Fast
• Factory-calibrated for
accuracy
• Minimal training need

MEASURE
PD techniques

UltraTEV Plus+™
multi-functional Partial Discharge (PD) instrument
• 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
surface/airgap:
ultrasonic
internal: TEV
Provides two techniques to QUICKLY locate &
measure surface and internal PD activity

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

UltraTEV Locator™
portable Partial Discharge (PD)
investigation system
surveys locates
SURVEYS & LOCATES PD activity in all
substation assets – including cables

UltraTEV Locator™
measures records
MEASURES & RECORDS PD activity in
all substation assets – including
cables

UltraTEV Locator™
RFCT cable sensor Ultrasonic Contact
ProbeTM
PLUG-IN OPTIONS for greater
versatility

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

7
1
Cable Data Collector™
Partial Discharge (PD) detection in cables
• 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

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

PD Emission
PD Hawk™
switchyard PD locator
SAFELY locates internal PD activity
in open terminal switchgear

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™

PD Hawk™
business benefits
• Prevents costly failures
• Rapid return on investment
• Gathers valuable data on
asset condition
• Extends asset life

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
Signals
detected
In this range
Signals out
here
are rejected
Signals out
here
are rejected
PD Hawk™

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

Record or download data for reporting or
comparison with future readings
Android Tablet/Phone App
PD Hawk™

PD Hawk™
complete kit
• Easy to use
• Portable
• Rugged

• Detection
• Location
• Measurement
• Recording
• Communication
• Alarms
• Analysis
• Interpretation
• Reports
UltraTEV Monitor™
substation monitoring and alarm system
24/7 MONITORING of substation
assets

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
Sensor Status
LEDs
Test and Reset
Buttons
Communications

Example Sensors
External TEV
Sensor
Ultrasonic
Sensor
Antenna (for cancelling
background noise)
Environmental
Sensor

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 Source B
Single Discharge Sites
Magnitude Source A
Precedence Source A Precedence Source B
Severit
y
– 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.

96
Instance Profile – Data Selection

97
Select Monitoring Time Period
Select the generated period
Summary Report

Thank you
For further information
Call +1 862 261 2759 or Email sales@eatechnologyusa.com

Partial Discharge Detection Products by EA Technology

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