Transformer Partial Discharge Test
A transformer partial discharge test requires more than a PD detector. The transformer must first be energized under the required electrical test condition. A suitable test power source provides controlled voltage, frequency and capacity while supporting a low-interference measurement environment.
Excitation and PD Measurement Are Different Functions
Provides the required electrical input for the transformer test arrangement.
Subjected to the defined test condition according to the applicable procedure.
Detects and evaluates partial-discharge signals through the measuring chain.
What Is a Transformer Partial Discharge Test?
Transformer partial discharge testing evaluates localized electrical discharge activity in the insulation system while the transformer is subjected to a defined electrical test condition. The overall test arrangement therefore has two distinct jobs: create the required electrical stress and measure the resulting PD signals.
A transformer PD test is powered by an excitation source that establishes the required voltage and frequency. Partial-discharge signals are then detected through a separate coupling and measurement chain. The exact voltage level, test sequence and acceptance criteria depend on the applicable transformer test procedure.
Create Electrical Stress
The transformer must be energized under the voltage and frequency conditions required by the selected PD or IVPD test procedure.
Detect PD Signals
Coupling and measuring equipment transfers the discharge information to a dedicated partial-discharge measurement system.
Evaluate the Test
Measurement results are reviewed against the test method, specified acceptance criteria and the transformer project requirements.
How Is a Transformer Partial Discharge Test Powered?
The excitation power path and the PD measurement path perform different functions. The power source establishes the electrical test condition; the measuring chain captures the partial-discharge information.
Variable-Frequency Low-Interference Power Source
Provides the selected test voltage, frequency and source capacity.
Excitation / Voltage Transformation Stage
Configured according to the transformer, required test voltage and laboratory arrangement.
Transformer Under Test
Energized according to the selected partial-discharge or IVPD test procedure.
Coupling / Measuring Device
Transfers the relevant PD signal into the measurement chain.
PD Measurement System
Detects, displays and evaluates partial-discharge activity.
Why Excitation Power Quality Matters in PD Testing
Partial-discharge measurement can involve weak electrical signals. The excitation source therefore needs to establish the required test condition without unnecessarily increasing the electrical background of the measurement environment.
Controlled Test Voltage
The source must support the voltage condition required by the selected transformer test arrangement and remain suitable for the connected load.
Low Source Contribution
Power-source-related interference should be controlled so it does not unnecessarily complicate background measurement or PD signal evaluation.
Suitable Output Quality
Sine-wave output, suitable frequency control and an appropriate isolation arrangement support repeatable transformer test conditions.
For transformer PD testing, the source must be selected as part of the measurement environment, not only as a conventional industrial AC frequency converter.
Review voltage, frequency, required capacity, DUT characteristics and the complete test arrangement together.
Why Variable-Frequency Power Is Used for Transformer PD / IVPD Testing
Transformer PD and induced-voltage test arrangements may require an excitation frequency selected according to the applicable test method and transformer configuration.
For the related application, see our guide to induced-voltage testing with partial-discharge measurement .
A variable-frequency source allows the laboratory or test-system integrator to configure the excitation condition instead of being limited to the incoming utility frequency.
Voltage, frequency and required source capacity should be reviewed together. The correct source configuration depends on the DUT and the complete test arrangement.
Transformer Partial Discharge Test Workflow
The exact transformer partial discharge test procedure depends on the applicable specification and project. At system level, however, the workflow normally follows a clear sequence from defining the test requirement to applying excitation and evaluating the PD measurement.
Define the DUT and Test Requirement
Confirm transformer data, test method, required excitation voltage, frequency and relevant acceptance requirements.
Configure the Test Arrangement
Define the power source, voltage transformation, compensation, coupling and PD measuring arrangement as required.
Set the Excitation Source
Configure the required output voltage, frequency and operating condition for the selected test setup.
Check the Measurement Background
Verify the test environment and measurement chain before evaluating the transformer PD response.
Apply the Test Condition
Energize the transformer according to the defined voltage, frequency and test sequence.
Measure and Evaluate PD
Use the dedicated PD measurement system to record and evaluate the discharge activity against the applicable criteria.
Test voltage steps, duration, connection details and acceptance limits should follow the applicable test procedure and project specification; they are not defined by the power source alone.
How to Select a Power Source for Transformer Partial Discharge Testing
A transformer PD test power source should be selected from the actual electrical test condition rather than from kVA alone. Transformer data, required voltage, frequency, excitation current and the surrounding test arrangement should be reviewed together before the source configuration is finalized. For a broader overview of power-source selection across different transformer test duties, see our transformer test power supply guide.
Configuration Starts from the Test Requirement
The power-source configuration can vary according to the required transformer test voltage, frequency, capacity, input conditions and the surrounding PD / IVPD test arrangement.
Define These Conditions Before Selecting the Source
Transformer type, rated power, rated voltages and relevant nameplate information.
Define the excitation or test voltage required by the selected transformer test arrangement.
Required operating frequency or frequency range according to the applicable test method.
Provide the required source capacity or excitation current when already known from the test design.
Identify the existing excitation or step-up transformer and its required relationship to the power source.
Confirm whether reactors or other compensation equipment form part of the planned test circuit.
Describe the existing PD detector and measuring chain so the excitation and measurement boundaries remain clear.
Provide the available incoming voltage, frequency and relevant installation conditions.
Voltage, frequency, transformer characteristics and the complete excitation arrangement can affect the required source configuration. Final selection should therefore be based on the actual transformer test condition.
Send the transformer nameplate, required test voltage and frequency, plus information about the existing excitation and PD measurement arrangement. SDACME can review the required power-source configuration.
Test Power Source vs. Partial Discharge Measurement System
These two parts of a transformer PD test solve different engineering problems. Separating the excitation function from the measurement function helps define the correct equipment and RFQ scope.
Transformer Test Power Source
Supplies the required AC excitation to the test arrangement.
Supports the frequency required by the selected transformer test method.
Configured according to the DUT and test arrangement.
PD Measuring Chain
Transfers relevant PD signal information from the test circuit.
Performed by dedicated partial-discharge measuring equipment.
Results are interpreted according to the applicable test criteria.
Other equipment such as coupling devices, PD detectors, voltage transformation and compensation equipment may form part of the wider transformer test arrangement and should be defined according to the specific project scope.
SDACME Power-Source Capabilities for Transformer PD Testing
SDACME supplies configurable variable-frequency AC test power sources for transformer partial discharge and induced-voltage test applications. The final source configuration is selected according to the required voltage, frequency, capacity, installation condition and the wider transformer test arrangement.
These are product-family reference capabilities. Final input, output and test-source configuration should be confirmed against the actual transformer PD / IVPD test requirement.
Multiple Configurations Built for Test Applications
The variable-frequency test power-source platform can be configured for different transformer electrical test requirements, helping laboratories and manufacturers match the source to the intended PD / IVPD application.
Configured and Built for Transformer Test Requirements
Transformer PD test projects can require different source capacity, voltage, frequency and installation conditions. SDACME reviews the application requirements before the test power source configuration is finalized for production.
Transformer data, test voltage, frequency, capacity and available site power are reviewed as configuration inputs.
The power-source configuration is manufactured and assembled according to the agreed project requirements.
Applicable functional and output checks can be completed under the agreed pre-shipment verification scope.
Transformer Partial Discharge Test FAQs
Common engineering questions about transformer PD testing, IVPD excitation and the role of the test power source.
What is a transformer partial discharge test?
A transformer partial discharge test evaluates localized electrical discharge activity in the insulation system while the transformer is subjected to a defined electrical test condition. The exact test connection, voltage sequence and acceptance criteria depend on the applicable test procedure.
What does the power source do during a transformer PD test?
The test power source establishes the electrical excitation required by the transformer test, including the selected voltage, frequency and source capacity. It provides excitation rather than performing the PD measurement itself.
Is a PD test power supply the same as a PD detector?
No. The power source energizes the test arrangement. A dedicated PD measuring chain detects and evaluates partial-discharge signals. Both functions may be required in the complete test setup, but they are different pieces of equipment.
Why is variable-frequency power used for transformer PD testing?
The required excitation frequency can depend on the transformer test method and test-system configuration. A variable-frequency source allows the required test frequency to be set independently of the incoming utility frequency.
What is an IVPD test?
IVPD refers to an induced-voltage test arrangement in which partial-discharge measurement forms part of the test evaluation. The excitation source and the PD measurement system continue to perform separate functions within the overall arrangement.
How is a transformer PD test power source selected?
Selection should consider the transformer data, required test voltage, frequency, source capacity or current, voltage transformation, compensation arrangement, available input power and the existing PD measurement setup.
Can a standard industrial frequency converter be used for PD testing?
Frequency conversion alone is not the only consideration. Transformer PD testing also requires attention to the source output quality, electrical background, isolation arrangement and compatibility with the complete test setup. The source should therefore be evaluated against the actual PD test requirements.
What information should I send for power-source configuration?
Send the transformer nameplate or rated data, required test voltage, test frequency, required capacity or current if known, existing excitation or step-up transformer, compensation equipment, PD measurement system, available input supply and project destination.
If the required source kVA is not yet known, send the transformer data and test requirement so the excitation-power configuration can be reviewed.
Configure the Power Source for Your Transformer PD Test
Send the transformer data and required PD / IVPD test condition. SDACME can review the required variable-frequency excitation source and prepare a project-specific power-supply configuration.
