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Brushless Alternator B rushless alternator is a machine that convert mechanical energy into elecrical energy, basically alternator couple with primover, when primover rotate an alternator induce voltage . Diesel generator There are six part of brushless alternator 1. Main armature 2. Main Field 3. Exciter armature 4. Exciter field 5. Rectifier assembly 6. AVR - automatic voltage regulator It look like one unit but there was two parts, Main alternator and another part was Exciter. Internal winding of alternator   AVR  automatic voltage regulator is a electronic device for automatically maintaining  generator  output terminal voltage at a set value under varying load and operating temperature. It controls output by sensing the voltage V out  at a power-generating coil and comparing it to a stable reference.  Rectifier is a electrical device which convert alternating current into direct current.   AVR...

Inverter duty VS Normal asynchronous motor   The basic difference in inverter duty and normal asyncronous motor is the cooling area and insulation class. In inverter duty motors the cooling area of the core is increased and in addition to that a separately powered cooling fan is placed instead of ingral cooling fan due to reduce the high heat generation during low speed. The winding insulation is incresed (aprox. 2 times) to atempt the high heat generation of the motor during low speed operation. Efficiency of the motor is higher than the normal induction motor as the cooling effect has been increased. We cant use normal induction motor in the invertar duty as the cooling effect will be lower in low speed operations and in normal speed harmonics effect to the motor temp. rise may resulted to failure of the motor. slightly higher costing effect for the purchase of inverter duty motors. https://amzn.to/2HYkQdx https://amzn.to/2JhZWr7 htt...

Polarisation  Index Good way to take aqurate IR test result ! The insulation resistance and polarisation index test carried out for evaluating  motors and generators windings deterioration of the insulation. Insulation is a form of organic compounds that contain water as a part of chemical,  Lower value of IR is indicate insulation was  deteriorated.  PI is a variation of the IR test. It is the ratio of IR measured after voltage has been applied for 10 minutes (R10) to the IR measured after one minute (R1), i.e. PI = R10 / R1   Interpretation of Polarisation Index results PI Condition of item under test <1.0 Hazardous 1 - 1.5 Bad 1.5 - 2.0 Doubtful 2.0 - 3.0 Adequate 3.0- 4.0 Good > 4.0 Excellent MI power bank psginfo266.blogspot.com

Insulation Resistance Insulation resistance was based on 'Ohms law', its also called Megger. High voltage is applied across the resistance, the current that flows through the insulation is measured. The ration gives the resistance R=V/I  Mohm Analog insulation tester Analog Hand-Crank Insulation Resistance Tester

Difference between Star and Delta connection Star connection :- 3 phase 4 wire system or 3 phase 3 wire system Speed of star connected motor are slow as they receive 1/√3 voltage. Need low number of turns saving in coppers and low insulation required.  Delta connection :- Only  3 phase 3 wire system possible. Speed of delta connected motor are high because each phase get s the total line voltage.  Need high number of turns and heavy insulation required.