OWTS® HV Technology - sebaKMT

OWTS ® HV Technology
for on-site testing and advanced diagnosis
of high voltage power cables for rated
voltages up to 380 kV using damped
sinusoidal ac voltages

OWTS ® technology has been introduced by Seitz Instruments AG in Switzerland
end of 90’s.
Since than worldwide almost 200 systems are successfully implemented for
testing and diagnosis of distribution and transmission power cables using different
OWTS ® (oscillating wave test system) solutions:
� OWTS 25 since 1999
� OWTS HV 250 since 2004
� OWTS M-series 28 since 2005
� OWTS M-series 60 since 2006
� OWTS HV 150 since 2007
� OWTS HV 350 since 2008
In this brochure you will find explanation, why the OWTS® technology is the most
advanced way for on-site testing and diagnosis of new and service aged
transmission power cables.
For further information you can contact:
SebaKMT
Seba Dynatronic Mess- und
Ortungstechnik GmbH
Dr. Herbert Iann Str.6
96148 Baunach / Germany
phone +49 9544 680
fax +49 9544 2273
www.sebakmt.com
Seitz Instruments AG
Mellingerstrasse 12
5443 Niederrohrdorf
Switzerland
phone 41 56 496 7480
fax +41 56 496 7485
www.seitz-instruments.ch
v.2010_01

Use
� as a part of commissioning on-site: to check on-site
the transportation, storage and installation possible
damage of the cable after completed factory test.
�after on-site repair: to check bad workmanship during
complete installation of the cable (including joints and
terminations).
� for diagnostic purposes: to estimate actual condition of
the service aged cable system by checking the insulation
degradation due to service operation e.g. 30…40 years.
On-site diagnosis
� by PD detection to demonstrate that the
insulation is PD free by determining the PD
inception voltage (PDIV).
� the margin between PDIV and the Uo is a
reliability indicator of a particular cable circuit.
� in the case of PD activity in the cable insulation
or cable accessories detection and localization of
the discharging weak spots.
� with regard to service aged power cables the
dielectric loss measurement at service condition
(power frequencies, electrical stresses) is very
valuable indicator about the thermal stability of a
particular cable circuit (OF cables).
On-site testing
� to detect insulation defects in HV and EHV power cables
during on-site testing voltages higher than Uo
� up to 1.7Uo…2.0Uo to demonstrate that
� the insulation is healthy (defect-free and/or nonaged)
and that insulation can withstand a high
voltage stress level,
application
� insulation is aged and/or consists of insulation
defects should have lower level of withstand
voltage.

Applicability for
HV and EHV
power cables
Results of several successful
comparison tests as published by
� Cigre (1990),
� TU Delft/Kema (1999),
� Cesi (2002),
� EuroTest (2007),
� TU Helsinki (2007)
� Prysmian Cables and Systems BV
� EPRI State Grid, China
have demonstrated the applicability of
damped ac (dac) voltages.
Important Standards
IEC 60060-3 High Voltage test techniques –Part 3: Definitions and requirements for on-site testing;
IEEE 400 Guide for Field Testing and Evaluation of the Insulation of Shielded Power Cable Systems;
IEEE 400.3 Guide for PD Testing of Shielded Power Cable Systems in a Field Environment;
IEC 60270 Partial discharges measurements;
IEC 885-3 Test methods for partial discharges measurements on lengths of extruded power cable;
IEC 60840 Power cables with extruded insulation and the accessories for rated voltages above 30kV
up to 150kV Test methods and requirements;
IEC 62067 Power cables with extruded insulation and the accessories for rated voltages above 150kV;
IEC 60141 Tests on oil-filled and gas-pressure cables and their accessories up to and including 400kV
part 2;
OWTS ® HV 150 system
OWTS ® HV technology uses damped sinusoidal ac voltages in
the range of 20Hz up to 500Hz
TEST TYPE
AC, DAC voltage test:
[IEC60060-3]
[IEEE 400]
[IEC60840]
[IEC62067]
AC, DAC voltage test
and diagnosis:
[IEC60270]
[IEC885-3]
[IEEE400.3]
application
DESCRIPTION
- AC test voltage 20-300 Hz substantially
sinusoidal,
- Test @ 1.7 U 0 / 1 h (but lower values are
also allowed),
- As alternative, a test @ U 0 / 24 h may be
applied
- PD level measurement in [pC]
- localization of PD in cable insulation
- localization of PD in cable accessories
- dielectric loss measurement in tanδ Δ
tanδ,

OWTS ® Technology
has been introduced in 1998 as a consequence of
experience in on-site ac testing on the one hand and the
technological progress in power electronics and advanced
signal processing on the other hand and it is characterized
by
� lightweights measured with max. 6kg/MVA
� compactness versus output voltage
� system assembling and voltage erecting effort
� necessary power demand for long lengths
� possibility of sensitive PD detection and tanδ
measurement
The damped alternating voltage (dac) is an oscillating switching impulse voltage (OSI) of quite low
damping and a frequency in the range of 20Hz up to 400Hz
Damped sinusoidal ac voltage
� has been introduced end of 80’s by Cigre
Study Committee 21 Insulated Cables as an
effective method for on-site testing.
� has lower destructiveness and the
combination with PD detection has become very
attractive.
� testing is since several years accepted
method for on-site PD testing and diagnosis of
polymeric and paper insulated HV and EHV
power cables networks.
� on-site applying of dac voltages is mostly
combined with PD measurements and dielectric
losses measurements.
method
OWTS ® HV 250 system
OWTS ® HV 150 system

Principles of damped sinusoidal ac (dac) voltage generation
� for the generation of dac voltages the
capacitance of the HV power cable in series in
a large air-core inductor in the range of few
H’s is charged with a continuously increasing
HV voltage with a low current in the range of
10mA up to 30mA.
� by linear charging with continuously
increasing HV voltage no ‘‘steady state’’ DC
conditions occur in the test object. After the
L•C loop is closed in a time e.g. < 1μs by HV
solid-state switch in the loop a sinusoidal
damped ac voltage with a frequency between
20Hz and few hundreds of Hz is produced.
OWTS ® HV 350 system
350kV HV divider and PD measuring unit
including measurement and control system
350kV external inductance build up with a
coil base, 3 coils and 1 coil with top
electrode
350kV switch unit
350 kV power unit, 2 parallel units in master
slave configuration which deliver 16 mA
HV Source
HV Solid-State
Switch
S
Process Control Unit
Data Storage
PD Analysis
Dielectric losses
estimation
Inductor L
Test Object: Power Cable
HV Divider
PD Coupling Capacitor
PD detector
� the dac voltage frequency is approximately the
resonant frequency of the circuit L•C.
� the maximum capacitance which can be tested
using dac system can be calculated in dependence
of maximum test voltage applied and the
permissible ac current in the resonant circuit and is
in the range up to 13μF.
method
C c

On-site testing and diagnosis using OWTS HV ® Technology
Voltage
testing
De-energizing and disconnection
of the HV power cable circuit
Connection of the OWTS ® HV system
Test object definition and IEC60270 PD calibration
Energizing the cable with dac voltages
Partial discharges
detection
Dielectric loss
measurement
Voltage withstand
diagnosis
Disconnection of the OWTS ® HV system
Analysis and report generation
features

Major steps in using on-site the OWTS ® HV Technology
Step 1: test object definition Step 2: IEC60270 PD calibration
Step 3: voltage testing and diagnosis
features
Step 4: PD mapping generation
Step 5: report generation

Information generation using OWTS ® HV Technology
Energizing using damped sinusoidal ac voltages
Testing and diagnosis
Advanced PD pulse analysis
TDR analysis of PD pulses
PD mapping in cable insulation and accessories
Multiple PD sites localization
Diel. Losses
information
Dielectric loss estimation
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0.40 0.80 1.00 1.36
L1 L2 L3
x Uo
Tan δ and Δtan δ in function of the test
voltage
IEC60270 standardized PD detection
PD-pattern generation
� due to similarity in PD occurrence at ac
voltage stresses during factory testing and
service operation it is recommended for on-site
testing and PD measurements.
� dac withstand test: the cable section can be
stressed with a selected DAC voltage stress for
selected time duration and the cable section
can be rejected if a breakdown has occurred.
� diagnosis: at certain voltage levels partial
discharges and dielectric losses can be
measured in function of time/voltage and used
for diagnostic purposes

Length [km]
0.25
0.5
1
2
4
8
16
20
Power cable rated
voltages [kV]
66
110
132
150
220
330
380
Application of the OWTS ® HV Technology
Examples of typical damped ac voltage frequencies for different lengths of two
typical 230kV power cables
Applicability for testing different power cable ratting voltages
38,1
63,5
76,2
86,6
127
190,5
219,4
XLPE (C=200pF/m) [Hz]
Uo [kV]
258
183
129
91
65
46
32
29
OWTS HV 150
X Uo
2,8
1,7
1,4
1,2
0.8
information
Oil filled (C=350pF/m) [Hz]
OWTS HV 250
X Uo
2,8
2,3
2.0
1,4
0.9
195
138
98
69
49
35
24
22
OWTS HV 350
X Uo
2,8
1,9
1,3
1,1

max. dac output- voltage
dac frequency range
test object capacitance range
HV charging current
max. dac current
PD measuring range
PD level detection and
bandwidth
bandwidth for PD-localization
accuracy of PD localization
dissipation factor
operating temperature
power supply
weight (without transport case)
dimensions
RAM1024 MB
USB port
protocol feature
HV Switch
data acquisition
Operation control
Calibration mode
TDR joint location in calibration
mode
User interface
Technical data of the OWTS ® HV Technology
OWTS HV 150
150 kV
(106 kVeff)
10 mA
app. 300 kg
OWTS HV 250
250kV
(176 kVeff)
20 Hz … 500 Hz
0,025 µF ... 13 µF
8mA
300 A
1 pC ... 100 nC
acc. to IEC 60270
150 kHz ... 45 MHz (automatic bandwidth adaptation for short and long
cables)
1 % of cable length, (min. 3m)
0,1 % ... 10 %
-10 °C ...+ 40 °C
app. 900 kg
RAM1024 MB
Integrated V.2.0
Integrated
LTT
optical link (100 FX)
Automatic / manual
Integrated
Remote client (Notebook or Tablet PC)
OWTS HV 350
350 kV
(247 kVeff)
16mA
app. 1100 kg
Integrated 100MHz DAQ and embedded controller

Facts about OWTS ® HV Technology
Applicable for HV power cables for rated voltages up to 380 kV
Applicable for testing long lengths of power cables
Reproduces ac stresses from the electrical network
Approved method and accepted by standards
Non-destructive and sensitive testing method
Combined with standardized partial discharge diagnostics
PD localization in cable insulation and accessories
Combined with dielectric loss measurement
Portable test system, compact design and low weight
Efficient and attractive for use in the field
Newest power-electronics and signal processing technologies
Straight forward technology and operation
Supports asset management decisions
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