Facilities

 

Equipment

 

Impulse Generator

Easily the largest piece of machinery housed by the lab is the 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 impulse generation. 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 as well as corona tests on polymer distribution insulators. 

Salt Fog Test Chamber

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, fourteen 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 our fourteen channel 50kHz DAC 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.

Tracking Wheel

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.

Shielded Room

 

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: 

• Tettex Automatic Capacitance and Dissipation Factor Tan-d Bridge, Type 2876A;
• Tettex Partial Discharge Bridge, Type 9127;
• Tettex Capacitance and Dissipation/Power Factor Test Set, Type 2818;
• Tettex SF6-filled Test Chamber, Type 2914;
• Tettex Heated Test Chamber, Type 2903A.

This test equipment can be used to evaluate dielectric properties and partial discharge performance of full size insulators at rated voltages. An image intensified video camera system is also installed in this lab for simultaneous viewing of the insulator under stress. Corona activity on the surface of a polymer distribution level insulator is being monitored and recorded with these systems.

High Power AC Generator

About AC Set

Voltage Divider

About Voltage Divider

Partial Discharge Detector

About PD Detector

Test Chamber

The test chamber is used for both wet and dry testing. It has four spray nozzles which simulate rainy conditions. Both the AC generator and Impulse generator can be fed into the chamber for testing.

UV Lamp

About UV Lamp

Faraday Cage

The faraday cage houses the controls for both the high power AC generator and the impulse generator, allowing us to perform tests in a protected mannor. The cage measures ___ by _____ by ___.

Chemical Laboratory

The chemical laboratory at Payton Hall allows us to perform various chemical tests. Two fume hoods provide adequate space to set up experiments easily and safely.