Thermo-Mechanical Conductor & Dead-End Testing ACCC Drake

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1 Introduction Thermo-Mechanical Conductor & Dead-End Testing ACCC Drake In early 2009, EPRI & EDF conducted a thermo-mechanical test on ACCC Drake size conductor and dead-ends at Kinectrics Lab. Based upon previous experience, a test protocol was developed wherein two conductor samples would each be terminated with ACCC dead-ends and wired in series so that the conductors could be thermally cycled from ambient lab temperature (~22 C) to 180 C, which is the ACCC conductor s maximum recommended (non-emergency) operating temperature. Following the completion of 500 thermal cycles, one-half of each conductor sample and two dead-end assemblies were pulled to failure. The remaining dead-ends and conductor samples were returned to EDF and CTC for post testing analysis. While the test protocol was initially developed to assess thermal aging of the ACCC composite core, thermocouple data that was gathered during the testing and post-testing analysis also provided valuable information about the performance of ACCC dead-end assemblies. Test Set Up Two conductor samples approximately 45 feet (14 meters) in length were terminated using conventional ACCC dead-ends (Figure 1). One conductor sample was tensioned to approximately 20% of its Rated Tensile Strength (RTS) of 41,100 pounds (~8,220 pounds) and held under constant tension during the thermal cycling. The other ACCC conductor sample was also terminated with ACCC dead-ends, but no tension was applied (Figure 2). Figure 1: ACCC Conductor & Dead-ends

2 Figure 2: Test Diagram The un-tensioned conductor sample was labeled dummy conductor. A jumper cable was attached to the south dead-ends so that electrical current could be applied to the conductors (wired in series) and the conductors could be heated equally as current was applied through the north dead-ends. Several thermocouples were placed at numerous locations in the dummy conductor and also at different locations in each dead-end and jumper terminal (Figure 3). Both conductor samples were placed in insulated boxes to improve thermal control (Figure 4). Figure 3: Thermocouple Locations in ACCC Dead-ends Test Protocol Figure 4: Insulated Boxes & Load Frame Two conductor samples and four dead-ends were initially subjected to 100 thermal cycles from ambient lab temperature of approximately 22 C (72 F) to 180 C (356 F). At the end of the first 100 thermal cycles, the tensioned conductor was pulled to 70% RTS, (~28,770 pounds) and held for 24 hours. This series was repeated five times, for a total of 500 thermal cycles and five 24 hour holds at 70% RTS.

3 Kinectrics Lab Results At the end of the thermo-mechanical sequence, the two conductor samples were cut in half leaving each dead-end in place. Lab grips, using potted resin, were then placed on one of the cut ends of each conductor sample (Figure 5). The two samples were then pulled to failure. The dummy conductor and its original ACCC dead-end pulled to failure at 101.6% RTS and the test conductor and its original dead-end pulled to failure at 102% RTS or roughly 42,000 pounds. These results demonstrated the ability of the ACCC conductor and dead-end assemblies to retain full strength after the thermomechanical and sustained load testing. Figure 5: Installing Lab Grips In addition to the mechanical results obtained by Kinectrics Lab during this testing, resistance and thermal data were also gathered on each of the dead-ends. This data showed that while some difference in resistance could be measured between the tensioned and un-tensioned test samples (Figure 6), the ACCC dead-ends and jumpers still operated >50% cooler than the conductor itself (Figure 7 & 8). Figure 6

4 Figure 7: Jumper & Dead-end Pad Temperatures (Conductor at 180 O C) Figure 8: Jumper Terminal & Dead-end Temperature (Conductor at 180 O C)

5 Figure 9: ACCC Conductor & Dead-end Assembly at Completion of Test ( sleeve thermocouple shown) During the final (500 th ) thermo-mechanical cycle when the ACCC conductor was at 180 C, the maximum temperature recorded at the tip of the dead-end (its entry point) was 120 C (Figures 8 & 9). The crimped area, where the electrical path occurs, increased in temperature from 45 C to 95 C over the course of the thermo-mechanical and high-tension sustained load test (Figures 3 & 8). The temperatures recorded were significantly cooler than ACSR or ACSS dead-end assemblies under similar elevated temperature conditions, primarily due to the added mass of the ACCC dead-ends compared to the smaller (less massive) ACSR and ACSS dead-ends (Figure 10). While some increase in resistance (and subsequent increase in temperature) is expected from any compression assembly over time, the minimal increase in resistance and temperature observed during this relatively severe test sequence confirmed robust connector design. Figure 10: ACCC & ACSR Drake Size Dead-end Housings (ACCC shown crimped)

6 Post Test Evaluation Following the thermo-mechanical testing at Kinectrics, the balance of the conductor samples were cut into several shorter lengths approximately one meter long (Figure 11). Half of these samples were shipped to EDF s lab in France and the other half were shipped to CTC s Lab in California along with several un-aged samples taken from the original reel of the ACCC Drake size conductor. Figure 11: Post Test Cut List CTC completed a series of Short Beam Shear Strength, Flexural Strength, and Tensile Strength tests of the aged and un-aged samples and compared the results (Figure 12). Figure 12: Post Test Evaluation Results (CTC)

7 Based on CTC s evaluation, it was found that the Short Beam Shear Strength increased from an average of 4,845 N (un-aged) to 4,970 (fully aged). The fully aged samples were taken from the tensioned conductor. The dummy conductor samples (that only saw thermal cycles but no tensile load) also showed slightly improved results compared to the un-aged samples (4,936 N). Data gathered from the post testing Flexural Strength test showed a slight decrease in flexural strength for the fully aged samples compared to the un-aged samples (2,317 N compared to 2,350 N). The dummy conductor showed a slight improvement (2,370 N). Tensile testing of the fully aged core samples and the dummy conductor core samples also showed a slight decrease in tensile strength after the earlier thermo-mechanical and high tension sustained load test protocol. The average strength of the un-aged core samples was 37,154 lbs (~108% RTS), while the average strength of the fully aged core samples was 35,905 lbs (~104% RTS). The dummy conductor core samples reached an average of 35,503 lbs (~103% RTS) at failure. Conclusions Based on the results of the thermo-mechanical and high-tension sustained load test performed at Kinectrics Lab, and the post test evaluation performed at CTC, both the ACCC conductor and ACCC dead-end assemblies exhibited excellent resistance to thermo-mechanical and sustained high tensile load fatigue. A copy of EDF s report is available from EPRI under the heading Specification for a Testing Procedure to Qualify Organic Matrix Core HTLS Conductors (Product ID # ). For Additional Information Please contact: Dave Bryant Vice President Technology CTC Cable Corporation 2026 McGaw Avenue Irvine, CA (949) dbryant@ctcglobal.com