Condenser Discharge Light System
Periodic maintenance of this system is fairly simple. Remember, however, that high voltages exist in the components of the system and you must be extra careful. One such area is the flash capacitor. This capacitor may contain as much as 2,000 volts. Anyone working on the light fixture should make sure that this capacitor is discharged before working on the light unit. The capacitor should bleed down through its resistor network in 5 seconds; however. the capacitor should be shorted out before any work is done inside the unit. In a flush unit short between terminals 7 and 10 ofthe terminal board with a shorting stick. In the elevated light, short the two contacts on the left side of the flashtube socket. That must be done before any work is done inside the light unit, such as changing a flashtube or cleaning the reflector.
WARNING Anyone working on a condenser discharge light system must make sure that the capacitor is discharged before working on the light unit.
Since these are sealed units, cleaning the reflectors rarely should be required. When such cleaning is required, be sure to use a nonabrasive cleaner. The lenses in both the elevated and flush units should be cleaned periodically, depending on the local conditions.
Inspect the timer contacts to see that they are clean and making good contact. If not, the stationary timer contacts can be adjusted. The timer gears ofthe master sequence timer require periodic lubrication. Match the grease to the ambient temperatures expected in your particular area. NEVER use a graphite-based grease, as graphite is electrically conductive. Check to see that both pairs of green indicator lights will light. When only one lamp is lit on either unit, the other bulb has burned out. To replace one of these bulbs, remove the front panel, pull off the colored lens, push out the old bulb, and insert the new bulb from the front of the panel. Replace the lens and panel.
Normally speaking, underground systems that are properly installed require little maintenance of the routine type. Since both the equipment and the cable are well protected from man and the elements, the system normally is not subject to the same problems that overhead systems experience.
In some areas, groundwater or dampness may create some problems for underground systems by increasing rust or corrosion. Racks and splice boxes may require more painting and other rust or corrosion maintenance. Look especially for rusted nuts on boxes and rack hangers. They should be cleaned and painted. The manholes and vaults should be cleaned. These areas should not be used for storage or should trash be allowed to collect in them.
Check the manhole walls for evidence of cracks, breaks, or other evidence of water seepage or leakage. Check empty ducts for plugs and evidence of water seepage.
You will find manholes with enough water in them to hamper or prohibit work operations. In such cases, bail the water out with a bucket and rope or pump it out with a manhole pump. Sometimes sump holes are built into the floor of manholes, and these provide places to bail from or to pump from the lowest places in the manhole. When water runs into a manhole from unoccupied ducts, hard rubber plugs are provided to stop or slow the water. When the manhole pump is used, place it in a position so the flow of water will be away from the manhole. That would be on the downhill side. Place the pump at least 10 feet from the manhole opening. The pump has a hose to be inserted in the manhole and an outlet hose to carry the water away from the manhole. Check cables for proper racking, making sure that they are trained in the proper direction and positioned so an ample cable radius is left for bends and expansion/contraction. This radius is basically 5 to 12 times the cable diameter, depending on the sheath type and the number of conductors. Make sure that 6 inches of straight cable exists for racking on each side of the splice. Check splices for evidence of leakage or tracking. Look for scrapes, burns, cracks, corrosion, or any other evidence of cable insulation deterioration. See that all cables are properly tagged for identification.
Check potheads and terminations that are attached to risers for leakage, tracking, and evidence of overheating or an overvoltage. Also, check the security of the mounting of the pothead and conduit.
Troubleshooting of cable systems is much the same as any other type of electrical troubleshooting. You need a thorough knowledge of the system as well as the ability to analyze problems. A review of the history ofthe system provides clues to present or future troubles. Simply using your eyes and head isContinue Reading