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4. OPERATION The transmission line assembly is a passive component of the overall broadcasting system, and, once installed, does not require operation instructions. Pressurization of the transmission line is a conditional requirement for the proper operation of the broadcast system. The pressurization system utilized should be capable of both monitoring and the pressure/humidity levels of dry air in the transmission line assembly according to specification requirements. CAUTION: Improper pressurization or other system operation resulting in use of the transmission line beyond its peformance specification limits can result in permanent damage to the transmission line assembly. WARNING: DO NOT TOUCH THE CABLE DURING SYSTEM OPERATION. Contact with the cable can result in severe shock or burns. 5. MAINTENANCE The semiflexible transmission line assembly has no moving parts or components expected to require replacement throughout the service life. 5.1 Scheduled Maintenance 5.1.1 Line Pressurization The transmission line requires constant dry air pressurization for proper operation of the broadcast system. Perform routine maintenance on the pressurization system according to the manufacturer's specifications. 5.1.2 Pressurization in Storage All SCL950 transmission line sections are pressurized to 10 psig (70 kPa) before shipment. While in storage, check these pressure levels in 14-day intervals. A pressure gage/air valve is mounted in each cable section and it can be accesssed easily by opening the shipping container. Any pressure reading below 5 psig (35 kPa) requires addition of dry air to restore the pressurization to 10 psig +/- 1 psig (70 kPa +/- 7 kPa). Since the ship/receive interval can exceed 14 days, it is important to check the section pressure levels at the first opportunity after arrival and add dry air as necessary. If a section has zero pressure, immediately after receipt or during temporary storage, repressurize it with dry air and tag the section for further inspection. When the sections are unloaded at the site, segregate the tagged sections for inspection as follows: 1. Remove the pressure plates by following the instructions in Section 3.5.1 Step 1 through 6. |
2. Inspect the inside of the alumninum conductor for excessive
oxidation. A light film of oxidation is acceptable, however a
heavy coating which flakes off when rubbed is unacceptable. CAUTION: Do not use any section with heavy oxidation. 3. Purge acceptable sections with dry air. To do this, reinstall the pressure gas/inlet valve assembly and reattach both pressure plates (reverse steps used for removal). Tighten the ANT end pressure plate bolts to 25 ft-lbs. Attach a dry air feed line to the inlet valve and adjust the TX end pressure plate bolts to allow some air to blend out. Purge the section for two hours. 4. After purging, high voltage test the section according to the procedure in Section 6.1. If the cable section passes, it can be used in the installation. Prepare the section for distribution to the site by reattaching both pressure plates (reverse the steps used for removal) and pressurizing to 10 psing (70 kPa) with dry air. CAUTION: Do not use the section if it fails the high voltage test. 5.1.3 Structural Supports Inspect the security of the transmission line structural supports in 12-month intervals. Examine the support structure, and ensure that the hanger cradles are securely attached to the support structure. Ensure that U-bolts firmly secure the transmission line assembly against the hanger cradles. Tighten all structural support hardware as required. Also, inspect the supports and support hardware for signs of rust staining or corrosion. If observed, touch up these areas with a commercially available rust-inhibiting paint. 5.1.4 Flange Joints Inspect the bolts securing the flange joints in 12-month intervals. Tighten them to a torque of 38 to 40 ft-lb, as necessary. Also, inspect the flange hardware for signs of rust staining or corrosion. If observed, touch up with a commercially available rust-inhibiting paint. 5.1.5 Surface Paint Inspect the painted surface of the transmission line, in 12-month intervals, for chipping and cracking. As necessary, touch up these areas. Only use white paint (#220129) as specified by Andrew Corporation. NOTE: The painted surface should also be kept reasonably clean. Water hoses can be used to wash away any dirt that has accumulated on the cable surface. |