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| The dielectrics and high voltage facility is currently distributed throughout several labs in Peyton Hall. A brief description of the tasks that are being performed in each lab follows, with accompanying photographs of some of the equipment used in this work. |
| This lab is equipped with a 1.4MV Marx type impulse generator. The generator is capable of providing standard lightning and switching impulses. A triggered chopping gap is also available to enable short impulses to be generated. Monitoring equipment includes a voltage divider with a Haefely type 711 impulse oscilloscope coupled with a Haefely type SV642 precision impulse peak voltmeter. Also housed in this lab are a Haefely partial discharge bridge type 561, and partial discharge detector type 562, and a Haefely capacitance and tan-d bridge type 470 and null detector type 471. Current work in this laboratory is centered on characterizing the behavior of polymer housed MOV lightning arrestors and their performance under polluted conditions, and corona tests on polymer distribution insulators. |   |
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An enclosed walk-in sized chamber is used to assess the effects of various high humidity environments on electrically stressed insulators. Samples are stressed at close to working voltages and typically 90% relative humidity atmospheres. Using the present arrangement, six samples can be tested concurrently. With the use of salt fog having a conductivity in the 100 mS/cm range, strong surface discharges and significant leakage currents are seen within 500 hours of testing in most polymers. Measurements of conduction current are made using a Gould Windowgraph recorder, and the humidity is maintained at the selected level with a Cool Fog controller. A high current capacity distribution transformer is used for the high voltage supply so that samples can be tested to breakdown. |
| The tracking wheel or rotating wheel system enables rapid assessment of surface discharge behavior for insulating materials. Descriptions of such systems can be found in recent IEC standards. The experiments in this lab use a saline solution with a predetermined conductivity as the surface wetting agent. Normally, two samples of the same type of material are evaluated in each test run. High voltage is supplied by a high current capability transformer, while leakage current is monitored with a Gould TA550 chart recorder. Current waveforms are also recorded with an HP54110D digitizing oscilloscope for detailed analysis of discharge pulse activity. Results indicate that surface degradation becomes severe and flashover generally occurs within 500 hours for currently manufactured polymer insulating materials. |
| Accelerated aging of polymer samples and whole insulators is being performed in an Atlas XR35 Weatherometer. This instrument allows full size samples to be subjected to a wide variety of simulated climatic environments, allowing controlled aging procedures to be followed. |  |
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A large shielded room is furnished with a MWB high voltage test set.
This system can be configured to provide ac, dc and impulse voltages in
the 200 kV range. The associated diagnostic equipment includes:
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| Housed in the simulation lab is a Pentium processor PC installed with recently purchased commercial finite element software for field simulation. The packages were supplied by Ansoft and consist of Maxwell 2D parametrics, 2D simulator, and 3D simulator. They are maintained to current update revision status and run on Windows NT. Polymer insulators and MOVs are currently being modeled and assessed for field and equipotential distribution, with emphasis on corona identification and suppression. This work is being performed in conjunction with experimental measurements. |  |
| Test samples made from various polymers and fillers are being fabricated in order to better understand the influence of the various constituents, and to assess their suitability for both outdoor insulator and transformer bushing applications. Thermosetting polymers are being examined for their compatibility with transformer oil, while silicon rubber is being investigated primarily for weathershed use. Fillers are being examined in detail for their influence on dielectric properties, mechanical strength and chemical compatibility, as well as aging of the host polymer under various outdoor conditions. Fabrication methods include mixing in a controlled environment, the use of a vacuum chamber for degassing, mold selection and set-up techniques. Cure schedules using elevated pressure and temperature are selected as necessary depending upon the chosen materials and their applications. |
| Dielectric liquid evaluation involves a variety of test systems. Stainless steel and glass test cells are used together with dc, ac and impulse high voltage supplies. The behavior of liquid and liquid/solid interfaces when subjected to high voltages can be monitored at both breakdown and prebreakdown levels. High speed photography is made possible with the use of a Quantrad 1D3 framing camera in conjunction with 6B and 26B plug-in units. This system provides the capability of obtaining time resolved framed images in the range of 50ns to 20ms per frame and exposure times from 5ns to 500ns. Partial discharge activity is monitored with either the aforementioned standard pd systems or with a Nicolet 4094A transient digitizer having a time resolution down to 2ns per point. Other optical measurements include the use of laser illumination for high speed photography of partial discharge activity with a Laser Science VSL337 dye cell laser, and also holography and kerr measurements for field effect monitoring with the use of an Apollo model 5H Q-switched laser. The CAMP facilities at Clarkson are available for routine material analysis for the liquids investigated. |