Carrier 17 Start Up & Operation Manual

Contents

Motor Maintenance (Open-Drive Machines) —A carefully planned and executed program of inspection andmaintenance will do much to ensure maximum motor avail-ability and minimum maintenance cost. If it becomes nec-essary to repair, recondition, or rebuild the motor, it is rec-ommended that the nearest Westinghouse apparatus repairfacility be consulted.In addition to a daily observation of the appearance andoperation of the motor, it is recommended that a general in-spection procedure be established to periodically check thefollowing items:1. Cleanliness, both external and internal2. Stator and rotor (squirrel-cage) windings3. BearingsCLEANLINESS — On open ventilated motors, screens andlouvers over the inlet air openings should not be allowed toaccumulate any build-up of dirt, lint, etc. that could restrictfree air movement. Screens and louvers should never be cleanedor disturbed while the motor is in operation because any dis-lodged dirt or debris can be drawn directly into the motor.If the motor is equipped with air filters, they should bereplaced (disposable type) or cleaned and reconditioned (per-manent type) at a frequency that is dictated by conditions. Itis better to replace or recondition filters too often than notoften enough.Totally enclosed, air-to-air cooled (TEAAC) motors andtotally enclosed, fan-cooled (TEFC) motors require specialcleaning considerations. The external fan must be cleanedthoroughly since any dirt build-up not removed can lead toimbalance and vibration. All of the tubes of the air-to-air heatexchanger of TEAAC motors should be cleaned using a sup-plied tube brush having synthetic fiber bristles (not wire ofany type). The standard cooler is equipped with steel tubes,however, in special cases aluminum tubes may be used andwire brushes can seriously erode the tube interiors over sev-eral cleanings. All tube brushing should be conducted fromthe front (fan end) toward the drive end of the motor suchthat dislodged dirt will not fall into the fan housing.Water spray washing of motors is not recommended.Manual or compressed air cleaning is preferred. If it be-comes necessary to spray wash a motor, it should bedone with extreme care. Do not aim high pressure spraysdirectly at air inlet openings, conduit connections, shaftseals, or gasketed surfaces to prevent the possibility offorcing water inside the machine.The stator windings of motors with open ventilation sys-tems can become contaminated with dirt and other sub-stances brought into the motor by the ventilating air. Suchcontaminants can impair cooling of the winding by cloggingthe air passages in the winding end-turns and vent ducts throughthe stator core and by reducing heat transfer from the wind-ing insulation surfaces to the cooling air. Conducting con-taminants can change or increase electrical stresses on theinsulation and corrosive contaminants can chemically attackand degrade the insulation. This may lead to shortened in-sulation life and failure.Several satisfactory methods of cleaning stator windingsand stator cores are offered below:Compressed Air — Low pressure (30 psi max.), clean (nooil) and dry air can be used to dislodge loose dust and par-ticles in inaccessible areas such as air vent ducts in the statorcore and vent passages in the winding end-turns. Excessiveair pressure can damage insulation and can drive contami-nants into inaccessible cracks and crevices.Vacuum — Vacuum cleaning can be used, both before andafter other methods of cleaning, to remove loose dirt anddebris. It is a very effective way to remove loose surfacecontamination from the winding without scattering it. Vacuumcleaning tools should be nonmetallic to avoid any damage tothe winding insulation.Fig. 45 — Typical Float Valve Arrangement78