Determine the maximum and minimum values
The dc machine in Problem 4.6 is self-excited.
(a) Determine the maximum and minimum values of the no-load terminal voltage.
(b) Rfc is adjusted to provide a no-load terminal voltage of 120 V. Determine the value of Rfc.
(i) Assume no armature reaction. Determine the terminal voltage at rated armature current. Determine the maximum current the armature can deliver. What is the terminal voltage for this situation?
(ii) Assume that If(AR) = 0:1 A at Ia = 50 A and consider armature reaction proportional to armature current. Repeat part (i).
Problem 4.6
The dc machine in Problem 4.3 has a field control resistance whose value can be changed from 0 to 150 Ω. The machine is driven at 1200 rpm. The machine is separately excited, and the field winding is supplied from a 120 V supply.
(a) Determine the maximum and minimum values of the no-load terminal voltage.
(b) The field control resistance (Rfc) is adjusted to provide a no-load terminal voltage of 120 V. Determine the value of Rfc. Determine the terminal voltage at full load for no armature reaction and also if If(AR) = 0:1 A.
Problem 4.3
A dc machine (6 kW, 120 V, 1200 rpm) has the following magnetization characteristics at 1200 rpm.
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The machine parameters are Ra = 0:2 Ω, Rfw = 100 Ω. The machine is driven at 1200 rpm and is separately excited. The field current is adjusted at It = 0:8 A. A load resistance RL = 2 Ω is connected to the armature terminals. Neglect armature reaction effect.
(a) Determine the quantity KaΦ for the machine.
(b) Determine Ea and Ia.
(c) Determine torque T and load power PL.
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Posted 28 Apr 2017 04:04 PM
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