TM5-6115-593-34NAVFAC P-8-631-34TO-35C2-3-463-2CHAPTER 3MAINTENANCE OF EXTERNAL POWER ASSEMBLY3-1. PREHEAT SYSTEMS CONTACTOR K107 AND HEATER CONTACTOR K109a. Removal. Refer to Operator/Crew and Organizational Maintenance manual for removal of preheat systemcontactor K107 (54, figure 3-1) and heater contactor K109 (54, figure 3-1).b. Repair. (See figure 3-2.) Repair preheat system contactor K107 (54, figure 3-1) by replacing contacts, armature,and coil, as follows:(1)Remove screws (1, figure 3-2) and cover (2). Disconnect wires from coil terminals. Remove coil (4) andmagnet assembly (3).(2)Separate the coil (4) from the magnet assembly (3).NOTEContacts are not harmed by slight discoloration and pitting. Do not file them. Replacement isnecessary only when the contact has worn thin.(4)To replace movable contacts (6), place contactor (nameplate down) on a flat surface and insert a replacementmovable contact finger.3-2. CONTACTOR K108a. Removal. Refer to Operator/Crew and Organizational Maintenance manual for removal of preheat system transfercontactor K108 (51, figure 3-1).b. Repair. (See figure 3-3.) Repair transfer contactor K108 (51, figure 3-1) by replacing contacts, armature and coil ineach contactor, as follows:(1)Remove screws (3, figure 3-3) and cover (4). Disconnect wires from coil terminals. Remove coil (6) from themagnet assembly (5).(2)Separate the coil (6) from the magnet assembly (5).NOTERecommended driving torques for items 3 and 7 are 18 to 21 inch-pounds (2 to 2.4 joules).(3)When replacing coil (6) the magnet must be installed with the word FRONT appearing as shown in figure 3-3.NOTEContacts are not harmed by slight discoloration and slight pitting. Do not file them.Replacement is necessary when the contact is worn thin.(4)Remove screws (7) on power plant. Replace movable contacts (8) by placing contactor (nameplate down) on aflat surface and inserting replacement movable contact fingers.3-3. CONTACTOR K120a. Removal. Refer to Operator/Crew and Organizational Maintenance manual for removal of motor contactor (57,figure 3-1).b. Test. Make test connections to motor contactor K120 as shown in figure 3-4.(1)Set switch to on and adjust variable load to provide 1000 watt load. Ammeter should read approximately 8.3amps.(2)Set switch to off.(3)Connect jumper across L1 and L2 terminals.(4)Remove and reconnect load to terminals X2 and T2.(5)Set switch to on. Ammeter3-1
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