transformer impedence testing

[Markho]

Hi:
I was wondering if it is possible to complete a transformer impedence testing the field? If so, what equipment is available to complete it. Thanks

 

[PERRO]

You can do the test with low voltage, you need a three-phase low voltage source to aplly excitation voltage for possitive sequence test and one-phase for cero sequense test.

You can find the procedure for this test in the IEEE Std. C57.12.90-1999.

 

[busbar]

See thread 238-56640 for discussion. Also, the test is described in §9 of IEEE Std C57.12.90.

A power source sized to the transformer OA or AA rating multiplied by its per-unit impedance is needed for the procedure.

 

[timohearn]

For further information on field testing of power transformers I recommend NETA Testing Specifications.
The NETA Acceptance Testing Specifications is a document to assist designers, specifiers, architects, and users of electrical equipment and systems in specifying required tests on newly-installed power systems and apparatus, before energizing, to ensure that the installation and equipment comply with specifications and intended use as well as with regulatory and safety requirements.

The Acceptance Specifications include topics such as Applicable Codes, Standards, and Reference; Qualifications of the Testing Agency; Division of Responsibility; General Information concerning Testing Equipment; Short-Circuit Analysis and Coordinating Studies, System Function Tests; and Thermographic Surveys.

A major featured section includes tests to be performed on Switchgear and Switchboard Assemblies, Transformers, Cables, Metal-Enclosed Busways, Switches, Circuit Breakers, Network Protectors, Protective Relays, Instrument Transformers, Metering and Instrumentation, Grounding Systems, Ground Fault Systems, Rotating Machinery, Motor Control, Direct-Current Systems, Surge Arresters, Capacitors, Outdoor Bus Structures, Emergency Systems, Automatic Circuit Reclosers and Line Sectionalizers, Fiber-Optic Cables, and Electrical Safety Equipment.

These specifications can be found on

http://www.netaworld.org