AC / DC Partial Discharge Test Systems
Hipotronics and Robinson Instruments team up FEATURES
once again as your reliable, single source supplier for
Partial Discharge Test Systems (PDTS). We offer a full Fully integrated Solutions with built-in test
line of AC and DC systems to suit a wide range of partial enclosure ensures simple installation and ease
discharge test applications. Our systems feature of use
Hipotronics PD free AC and DC power supplies and the
Robinson Instruments DDX® Series of partial discharge Reliable and proven AC/DC power supplies
detectors. We bring together years of experience and and partial discharge detectors from a single
provide a flexible product able to meet a variety of vendor
applications. DDX® Series of Robinson Instruments
partial discharge detectors enable a wide variety
System performance begins with having quality of PD measurement systems
components. All PDTS components are manufactured in-
house giving us the ability to optimize their quality and
how they function together as a system. A worry-free
system always begins with quality components built to the BENEFITS
highest of standards.
Flexible Solutions - regardless of your PD test
Our Fully Integrated Systems with Test Chambers are a application we have the right combination of
complete single piece solution to PD testing of HV equipment to suit your requirements.
components and insulation materials. They are simple to
Field Experience – We have been designing,
install and easy to use.
manufacturing and installing PDTS for over 35 years.
Pick and choose your solution, from a multitude of Single Source Supplier - All the components are
options. Our standard product offering includes both designed, manufactured and tested by a single supplier
stationary and mobile skid mounted systems for easy guaranteeing their ability to function together.
relocation within your factory as well as fully integrated
systems with enclosed test chambers. Over the years Test Automation & Report Generation - With the
we’ve found these systems fit most of the applications OT248 controller and DDX® series of PD detectors
we’ve come across. With a variety of control options and control of the power supply and PD measurement can
partial discharge detectors the system is optimized for be done from a single PC.
Engineering services are extremely important in the APPLICATIONS
success of your Partial Discharge Test System. Our
Engineers have the design, manufacturing and field Partial Discharge testing of:
experience to help
you get the most from Capacitors
your system. They Bushings
can assist you with Molded Products
suitability of your test Generators
area for PD testing Switches
and work with you Insulation Material
designing a test area
that will provide the
optimum, sensitivity. Cable
We can also offer Insulated Bus Bars
installation assistance Transformers
and staff training as
part of our
engineering services. Aerospace Components
ONE LINE DIAGRAM OF PDTS (AC ONLY)
1. Double Shielded Isolation Transformer
(available upon request)
2. Power Cubicle
2a. Main Power Circuit Breaker
2b. Voltage Regulator
2c. HV on/off contactor
3. Line Filter (available upon request)
4. High Voltage Tank (section)
5. Power Separation Filter
7. Partial Discharge Detector
8. HV Calibration Injection Capacitor
9. Test Object
Note the objects in red are the items that may be needed for a complete partial discharge test system. Not all items
are necessary for every PD testing application.
DC PARTIAL DISCHARGE TESTING
DC partial discharge testing is very different from AC PD testing. Although the measuring circuit does not differ
between AC and DC the analysis of the data does. The occurrence of PD in an AC circuit corresponds and is normally
referenced to the voltage and phase angle of the sine wave of applied test voltage. Resulting in discharges typically
seen at fixed locations on the ellipse (sine) when looking at the elliptical display (1 Hz of applied test voltage).
Detection of DC partial discharge involves counting the number of pulses of a specified magnitude over a period of
time. These discharges in a high voltage DC circuit have none of the regularity as compared to an AC high voltage
circuit. The partial discharges in the DC PD detection circuit occur at random points on the display vary in magnitude
and are very short in duration.
We offer a full line of PD free DC Power Supplies. In addition, we also offer integrated systems with an AC and a DC
power supply (as shown here), a test chamber and a single PD detector to make the measurements. Consult the
factory for additional information.
Double Shielded Isolation Transformers (DSIT) are recommended for high voltage test systems intended for
partial discharge tests. This transformer serves two important functions. It isolates the test system from the power
system ground and it attenuates high frequency noise that may appear on the mains. Ground isolation is particularly
important. It permits the ground for the test system to be selected for the minimum PD background noise levels.
This ensures that the test system can achieve the highest possible PD sensitivity. The user must provide protection
for this transformer.
The Regulator Section configuration is dependent upon the power rating of the system. PVT voltage regulators
are typically used on all systems with a power rating above 40 kVA. The PVT voltage regulator differs from others
types in that moving, copper contacts eliminate shorted turns. PVT’s have linear impedance versus position
characteristics. Commercial grade toroidal autotransformers are usually used for systems with power levels 40 kVA
and below. These voltage regulators use carbon brushes to contact the voltage winding. Also included in this
section are the main power circuit breaker, a fast output overload, backup protection and a main power contactor.
Line Voltage Filters (LVF) are designed to attenuate electrical noise signals in the PD measurement band, which
may be conducted by the mains into the HV test circuit. These filters are passive networks consisting of series
inductors and shunt capacitors, usually in a “pi” configuration. The characteristics of this configuration minimize pass
band loss and maximize high frequency attenuation.
SYSTEM COMPONENTS (C0NTINUED)
High Voltage Transformers are constructed in one of five mechanical packages: air insulated HV transformers, oil-
filled epoxy (insulated) bonnets, oil-filled metal tanks, oil-filled fiberglass (insulated) cylinders or modular cascades.
The exact configuration is based upon the voltage and power ratings of your system and can be determined by
referring to the AC Dielectric Test Set Catalog. For metal tank designs the bushings are either epoxy or porcelain
condenser type. For systems rated up to 100 kV, horizontally mounted epoxy bushings are supplied. Epoxy
bushings have the advantage of low current drain and reduce the output current available to the test load by only a
small amount. For systems rated above 100 kV, porcelain condenser bushings are used. The current drawn by the
porcelain bushing will be measured by the current meter and reduces the available output current.
Power Separation Filters (PSF) and HV Calibration Injection Capacitors (CIC) are designed specially for
partial discharge applications. The capacitors used are designed and manufactured at Hipotronics and have high
self-resonant frequencies, high stability and low partial discharge levels. They are mounted on a base with a suitable
top electrode. Outputs on the PSF’s include PD detector output, arc detect output and kilovoltmeter output.
AC TEST SYSTEM CONTROLS
The PLC based controller, CAC-PLC, offers
great flexibility & durability with little
economic impact on the test project.
This controller offers a large LCD display,
large soft key buttons as a user interface,
programmable output voltage & dwell timer
all in a standard 3U size. Recommended
for projects that do not require large
amounts of test data manipulation.
The advanced OT 248 controller is a Windows XP, rugged, industrialized computer designed to be operated with
High Voltage Test equipment. This state of the art operating terminal is designed for operation in conjunction with
all models of our DDX® product line. Additionally the unit offers advanced office software which allows the user to
pre-program test sequences away from the
test equipment & then upload via Ethernet
connection or USB connection.
User safety is the primary importance
during all high voltage testing, the OT 248
offers unique key stokes required to
energize the high voltage to prevent
accidentally energizing the unit.
Additionally the operating terminal comes
standard with provisions for a series
interlock and a standard issue emergency
Downloading test data from the OT 248 is easily accomplished via the USB port on the face of the unit via USB
connection port or a network connection. The network connection also allows for remote control of the unit from a
second PC (with optional software). Remote control can be especially beneficial if there is a host computer where all
date review is done and stored.
PARTIAL DISCHARGE DETECTORS
The DDX® Series of Partial Discharge Detectors are offered with our AC/DC PD Test Systems. Two versions are
available the DDX®9101 and the DDX®7000 and are designed to meet the IEC and ANSI/IEEE standards for partial
The DDX®9101 is a simple, inexpensive detector designed with
pass/fail testing in mind. With this detector you can preset a
maximum allowable PD level and when it’s exceeded during the
test an indicator lights on the screen. A software package is
available for remote control and test reporting features using an
Ethernet connection. This partial discharge detector is designed
with only AC testing in mind.
The DDX®7000 is an advanced, computerized partial
discharge detector with complete advanced features and is
suitable for more advanced measurement and analysis of
partial discharges. It includes test reporting features as
part of the standard package. A software package is
available for advanced partial discharge analysis such as
finger printing and intensity charts. The DDX®7000 offers
the industry leadings software for DC partial discharge
When the DDX®9101 or DDX®7000 are combined with the
OT248 control the user can have a fully automated test station
that operates the power supply and performs PD testing from
ENSURING THE FUNCTIONALITY OF THE SYSTEM
When installing a system for partial discharge testing steps must be taken to provide service to the test system,
which will allow adequate performance (measurement sensitivity). Isolated grounding, input power quality / line
conditioning and the physical location are key considerations. Proper grounding of the test system is critical for both
safety and accuracy of measurements. Grounding resistance should be kept to a 2 ohm level or if unattainable then
a level sufficiently low for normal equipment operation as specified by the power utility. The test set should then be
connected to the factory ground directly using a center point (star point) system to avoid ground loops. The
grounding system of the test set must also be totally independent of other grounding systems in the factory to
assure that no external noise will be transmitted. Additionally the grounding system must be physically separated
from all other buried conductive elements such as other grounding systems, pipes and cables. Isolating the grounds
reduces the amount of background noise introduced into the test circuit, which can appear as partial discharge on
the test set.
ENSURING THE FUNCTIONALITY OF THE SYSTEM (CONTINUED)
Input power quality is also important. The input line should have a stable voltage without rapid fluctuations caused
by load changes. It should show no significant harmonic distortion of the voltage wave usually caused by operation
of power SCR’s or by unbalanced loads connected to three-phase systems. The line should be supplied from a
relatively large transformer to minimize the load effect. Using a separate feeder line from the main feeder board to
the test set with no other industrial loads connected is the best solution. The input line should be housed in a
separate feeder trough. Isolating the input lines minimizes the amount of background noise introduced into the test
circuit by capacitive coupling from other sources in the factory. If adequate power quality cannot be made available
then additional line filtering necessary to eliminate harmonics will be required.
The location of the test system in a factory is also a concern. The system should be placed away from electrically
noisy equipment (i.e. variable speed drives, DC machines). Placing the test system near these types of machines can
introduce transient and radiated noise into the test circuit, which may be very difficult to screen and filter out.
Taking these measures will help provide proper background PD levels and ensure sufficient measurement sensitivity.
Of course an in many cases operating within a shielded enclosure or room may be the only way to achieve required
WHAT IS PARTIAL DISCHARGE?
Partial discharge testing is an integral part of the manufacturing process for high
voltage apparatus and components, but what is partial discharge and what does it
Partial discharge (PD) is a voltage breakdown between two electrodes that
partially bridges the electrodes (see figure 1), such as a small void or cavity in an
insulation system. In a typical test sample, the PD appears as a small, fast-rise
pulse superimposed on the high voltage at the terminals of the sample. This
apparent charge is very small, is measured in pico-Coulombs (10-12 Coulombs)
and can indicate degradation over time in an insulation system. On the right is a
series of circuit diagrams depicting the cycle of a discharge event.
WHY PARTIAL DISCHARGE TEST?
Partial discharge measurement is a standard method for determining the quality of electrical insulation. PD can be
caused by poor designs, manufacturing faults, mechanical damage or aging. We can detect it, measure the value of
it, locate it (in HV power cable) and then evaluate it. The ability to measure low values of PD is referred to as
sensitivity and depending upon what is being tested; desired levels can vary from 2 pC to over 1000 pC. Partial
discharge testing is required by international standards and is performed as a routine test and as a type test, but also
used as an evaluation point for quality tests.
UNDERSTANDING YOUR TEST ENVIRONMENT
When a high level of sensitivity is required for PD testing, the level of background electrical noise becomes important.
It can show up on a PD detector and be mistaken for PD or be of such a large magnitude so as to mask the actual
PD. Our Partial Discharge Test Systems are specifically designed for PD testing with a test circuit, which contains
very little background noise. Background noise can be generated in a variety of ways some of which are described
Proper grounding is vital when installing a PD measurement system in a factory. If a test set is not properly
grounded the return path of the test circuit can pick up stray current from other manufacturing equipment and may
make PD testing impossible. Stray current can appear as sharp PD spikes on the detector or as severe PD distortions
causing a loss of sensitivity. The grounding system must be physically isolated from all other buried conductive
elements such as other grounding systems, pipes and cables.
Line conditioning and input power quality are key to a successful installation. The input line from the utility
transformer to the test set can pick up noise (conducted) generated by other equipment in the factory when it is not
kept separate (interference reduces by the square of the separation distance). This noise can be visible on the PD
detector. Ensuring that the input power is taken directly from the utility power supply, installing the feeder cable in a
separate input duct, isolating it from other power cables and adequate filtering can help eliminate this problem.
Ambient (radiated) noise from the factory will also affect partial discharge measurements. PD measurements are
made in a frequency range from 30 kHz to 500 kHz. Factory equipment often radiates interference at these
frequencies. The test system should be shielded from or placed away from electrically noisy equipment; particularly
variable speed drives and DC vector machines. Using a dedicated test facility, a shielded room or a test chamber are
all ways of reducing ambient radiated noise.
The testing procedure must also be carefully considered. While complex fixturing and in-line testing may
smoothly integrate the test area into the production line, they can also make PD testing difficult. Careful
consideration to system grounding and the filtering of ambient noise becomes very difficult when testing on-line
because of nearby manufacturing equipment. Also complex fixturing used to connect the high voltage supply to the
test object is often not designed to be PD free.
We offer a full range of services where our High Voltage Test Specialists assist you with your system from start to
finish, ensuring you get the most out of your new investment. Our services can start beforehand with a on-site visit
inspecting the proposed test area to determine the feasibility of the area for PD testing and what action items are
required for making the area suitable for partial discharge testing. Recommendations are made for grounding and
line conditioning requirements and may require installing a dedicated input line and feeder trough for the input line
or line filtering. Suggestions can be made how to best minimize the effects of the surrounding factory on the
sensitivity of the measurement system. We can also offer recommendations on how to best integrate the test set
into the production process to ensure the test set can meet manufacturing requirements as well as obtain required
sensitivity. Layout of the test area and clearance requirements appropriate can be included. We also offer
installation assistance and operator training services.
SCOPE OF SUPPLY ORDERING INFORMATION
Qty. 1 AC Dielectric Test Set* Options
Qty. 1 Low voltage Filter DDX9101-SFTW
Qty. 1 Regulator and Controller Data acquisition and remote control software for
Qty. 1 HV Section the DDX9101.
Qty. 1 set Multiconductor Cable interconnects.
Qty. 1 set Instrument Coaxial Cables DDX-DA3
Advanced analysis software for DDX7000. Allows
Qty. 1 Power Separation Filter three-dimensional plots, calculation of IEC
integrated quantities, and discharge pattern
Qty. 1 HV Calibration Injection fingerprinting.
Qty. 1 500 VA Isolation Box Accessories
Qty. 1 Partial Discharge Detector 753-US
Qty. 1 Digital PD Detector (9101 or 7000) Miniature Discharge Simulator, 0.5, 5 and 50 pC
Qty. 1 Input Line Cord outputs
Qty. 2 Coaxial Cable (Blue)*
Qty. 2 Coaxial Cable (Green)* 753-US1
Qty. 2 Coaxial Cable (Red)* Miniature Discharge Simulator, 5, 50 and 500 pC
Qty. 1 Transient Filter Unit (3-channel) outputs
Qty. 1 Computer keyboard (only with DDX7000)
Qty. 1 Computer mouse (only with DDX7000) 753-US2
Miniature Discharge Simulator, 2, 5, and 10 pC
Qty. 1 Set of Manuals for power supply and outputs
partial discharge detector
Qty. 1 Set of calibration certificates for power Two pulse generator including batter charger and
supply and partial discharge detector rechargeable battery
* Note: For Standard Systems coaxial cable lengths CIC-LV
are 25 m. For Mobile Systems and for Fully Low voltage calibration injection capacitor
Integrated Systems the cable lengths are set to
match the system. SPKDDX7000
Spare Parts Kit for DDX7000
Note: The configuration (number of pieces) of the
system may vary. This depends upon the system SPK7XXX-XXX
ratings and type. Spare Parts Kit for AC Dielectric Test System
(part number depends upon ratings and controls)
Double Shielded Isolation Transformers (ratings
based upon input power)
Line Filters (ratings based upon regulator ratings)
European Contact Locate your local USA Contact
Haefely Test AG sales representative at Hipotronics Inc.
Lehenmattstrasse 353 www.high-voltage-hubbell.com 1650 Route 22
CH-4028 Basel PO Box 414
Switzerland Brewster, NY 10509 USA
+ 41 61 373 4111 + 1 845 279 8091
+ 41 61 373 4912 + 1 845 279 2467
Hipotronics has a policy of continuous product improvement. Therefore we reserve the right to change design and specification without notice PDTS-DS / 05.2009