Page 335 - CTS - Mechanic Diesel - TP

MECHANIC DIESEL - CITS

The frequency should be kept constant by adjusting the prime mover speed whenever necessary.
2 Slowly increase the load current to1ampbys witching`ON’ the lamp sone by one.Record all the readings in
Table2.
Switch on the lamps equally in all the three phases so that the load is balanced.
3 Increase the load current equally on all the three phases of the alternator to it srated value by switching on
the lamps in steps of 1amp.Foreachstep,note down the current,voltage and the P.F.frequency and tabulate the
readings in Table 2.
4 Reduce the load gradually to zero.Open the lamp load by switching off the T.P.I.C. switch.

TASK 3: Loada 3-phase alternator by a3-phase motor (inductive) load
1 Close the T.P.I.C. of the motor load and start the motor by the D.O.Lstarter.Read and record I ,V ,P.Fand
L
L
frequency inTable 3. Switch `OFF’ the T.P.I.C. switch of the motor load.
Frequency
S. Loadcurrent equal in Terminal Power Power=
No. all the three phases I L Voltage VL kept Factor cos Ø L L Remarks
I cosØ
constant

TASK 4: Determine the voltage regulation of an alternator
1 Close the T.P.I.C. switch of the motor load and start the motor by the D.O.L starter.
2 Close also the T.P.I.C. switch of the lamp load and increase I upto the alternator’srated value in steps of one
L
ampere. Read and record the values of I , VL&P.F. frequency in Table4.
L
3 Reduce the load and switch off the alternator.
4 Draw the three curves for the 3 sets of reading as recorded in Tables 2, 3 and 4 in the same graph showing
the terminal voltage versus load current. Keep the terminal voltage in theYax is and load current in the X-axis.
5 Compare the power delivered to the
• resistive
• inductive (partially resistive)
• resistive/inductive loads
• With the corresponding line current and line voltage, and P.F.- at least three different line current values

6 Calculate the voltage regulation for the above different loads at 5 and 10 amperes by using the formula:
Percentage voltage regulation (%V )
R
%V = No.load voltage – Full load voltage X100
R
Fully load voltage

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CITS : Automotive - Mechanic Diesel - Exercise 18.4