NANO

622 ELECTRICAL Rectifier assembly check: Remove the rectifier assembly from the unit and check as follows: (a) Testing of positive heat sink diodes (i) Continuity check Connect as shown in figure 55. Use multimeter with two probes. Connect the negative probe of the multimeter to positive terminal and positive probe to phase connecting points one by one on the rectifier assembly. It should not indicate open circuit. Replace the rectifier assembly if it is open circuit. (ii) No Continuity check Connect as shown in figure. Use multimeter with two probes. Connect positive probe of multimeter to positive terminal and negative probe to phase connector points one by one on the rectifier assembly. All diodes should indicate no continuity. If there is continuity it indicates short circuit. Replace the rectifier assembly Using 230 volt AC main supply connect a 15W bulb as shown in figure. Connect one of the probes to the slip ring and the other to the shaft. The lamp should not glow. If the lamp glows it indicates earthing. Replace the rotor assembly. • Stator insulation test: Using 230 volt AC main supply connect a 15W bulb, Connect one of the probes to any of the three leads and the other probe to the body. The lamp should not glow. If the lamp glows it indicates poor insulation. Replace the stator assembly. • Stator winding resistance check Use Ohm meter with two probes connect lead 3 and lead 1. The Value should read around 0.180 to 0.202 Ohms at 20°C. Repeat it between star connection and lead 2 and 3.