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2. A dc machine (6 kW, 120 V, 1200 rpm, Ra = 0.2 Ω, Rf =...

2. A dc machine (6 kW, 120 V, 1200 rpm, Ra = 0.2 Ω, Rf = 100 Ω) has the following open circuit characteristics at 1200 rpm. If (A) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.8 1.0 1.2 1.4 Ea (V) 5 20 40 60 79 93 102 114 120 125 130 It has a field control resistance whose value can be varied from 0 to 150 Ω. The machine is driven at 1200 rpm and separately excited from 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 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.

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