Electrical research and testing laboratory for transformers
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Electrical research and testing laboratory for transformers
Research for practical application
The Electrical Research and Testing Laboratory (ERT Lab) in Nuremberg offers a wide range of testing and analysis activities in the field of energy technology.
Our portfolio for testing, research and development in the Electrical Research and Testing Laboratory:
Materials technology also plays an important role at the Electrical Research and Testing Laboratory: Specially developed devices for oil treatment, drying and impregnation and for other versatile process materials enable quality-relevant criteria, such as purity, cleanness or dryness of the insulating materials to be taken into account. This guarantees meaningful and precise results.
Determining of the material properties forms the basic prerequisite for proper and efficient use. The quality and production stability of the materials and components can be investigated via material testing using the facilities in the lab, thus ensuring a continuously high quality of the electrical operating equipment. Depending on the particular demands, various standardized tests can be performed in accordance with international standards in the Electrical Research and Testing Laboratory. Moreover, each test can also be adapted to reflect individual customer requirements.
Standardized material analyses based on defined standards:
The aim of this test is to determine the dielectric strength of all types of insulating materials under AC voltage. Empirical tests are conducted for this on material specimens which have been appropriately prepared and the results statically evaluated. The specimens can be specially and individually prepared. The test parameters are variable and can therefore be specifically selected.
The aim of this test is to determine the dielectric strength of all types of insulating materials under DC voltage. For this material testing, the test specimens are cut to an appropriate geometric size, similar to the test using alternating current, and prepared in several process steps for the actual test. The parameters for the test, such as specimen thickness, voltage increase, etc., are variable and can be specifically selected, or can also be applied according the specifications given in the standard.
The aim of this material testing is to determine the partial-discharge inception voltage for insulating materials, such as laminated densified wood or laminated board, under AC voltage. A background noise level of only < 1pC permits highly sensitive measurements to be made. Special attention must be given here to the dimensions and manufacturing precision of the specimens. Testing can be conducted from the inception of partial discharge up to complete failure, i.e., breakdown of specimens, of the specimens.
With the aid of the polarization and depolarization current (PDC) measurement, various properties (among other things the "apparent conductivity" of an insulating material, or of an insulating system) can be determined. This method can also be used to examine and characterize the dielectric loss behavior of the insulating materials. These measurements are conducted in a guard ring arrangement developed specifically for this purpose and can also be varied by a wide range of parameters, such as voltage stress, measuring period, temperature and gap width. The potential temperature range extends from
-40°C to +120°C.
Alternative procedure for determining the specific volume resistance (see PDC measurement) and the specific surface resistance using a guard ring arrangement. Typically, DC voltage is applied to the specimen for 1 minute to determine the surface resistance. By contrast, the values for measurement of the specific volume resistance are determined at defined times, typically up to 100 minutes.
Using a classic Schering measuring bridge or a computer-based digital measuring system, the loss factor is determined from the currents of two test branches (reference branch with known parameters and the specimen branch) via phase shifting of the fundamental oscillation. Measurement can be performed within a temperature range of - 20°C – +120°C.
Standard test for determining the electrical breakdown voltage of insulating fluids. As it is generally applied, the breakdown voltage of insulating fluids is not a basic material property, but, rather, an empirical test procedure that is performed to demonstrate the presence of contaminants, such as water and suspended solid particulate matter and to provide information about the feasibility of a drying or filtration treatment process.
Method for the quantitative determination of water in materials by titration. A known quantity of insulating liquid or of the oil-impregnated pressboard is heated in a heating chamber. The developed water is added in carefully measured amounts to the titration cell, where the coulometric titration will take place.
Thanks to its equipment and its highly qualified personnel, the electric research and testing lab can also satisfy special customer needs and demands. As a result, every single step of the test can be specifically coordinated and individually defined with the customer – from test planning, with preparation of the performance specification, up through planning and fabrication of the specimens and the test setup, all the way up to performance of the test sequences, with subsequent evaluation and documentation.
In the planning phase, the latest CAD and 3D software tools can be used to design test setups and to subsequently simulate them using the corresponding electrical and magnetic analysis tools in order to identify the optimal test setup. We also offer testing of electrical components included in our performance category. This enables type testing and routine tests to be performed for bushings or capacitors, for example:
Planning and development of a test facility for automatic performance of electrical breakdown tests with voltages up to 650 kV (LI)
Type testing of a bushing with electrode system for the use in natural ester filled high voltage components
The Electrical Research and Testing Laboratory is equipped with two independent test building sections; the high-voltage lab and the air-conditioned test cell. Both of these sections can be used in parallel with and completely separately from one another. Moreover, both sections are 100% shielded against external interference, thus guaranteeing an extremely high measuring accuracy.
In addition to these two facilities, systems are also available for initial and post-treatment of materials, for material storage and for machining. Our portfolio also includes an oil treatment unit, vacuum and recirculation drying cubicles and a machining workshop for handling of different materials. Specimens and test equipment can therefore be individually prepared and modified.
Well and fully equipped workshop for test piece preparation and modification of numerous test setups
The Electrical Research and Testing Laboratory Nuremberg