### 81. Due to armature reaction, the main pole flux of a d.c. generator is

(i) weakened only

(ii) distorted only

(iii) weakened as well as distorted

(iv) none of the above

Answer: (iii) weakened as well as distorted

### 82. The 0.C.C. of a d.c. generator is also called its ……. characteristic.

(i) magnetic

(ii) internal

(iii) external

(iv) performance

Answer: (i) magnetic

### 83. The line representing the critical resistance of a d.c. generator ……. its O.C.C.

(i) intersects

(ii) runs parallel to

(iii) just touches

(iv) none of the above

Answer: (iii) just touches

### 84. Which of the following generator provides approximately constant voltage from no-load to full-load ?

(i) series

(ii) shunt

(iii) flat-compounded

(iv) over-compounded

Answer: (iv) over-compounded

### 85. A shunt generator gives its greatest voltage at

(i) no-load

(ii) full-load

(iii) half full-load

(iv) none of the above

Answer: (i) no-load

### 86. The level of compounding in a cumulatively compounded d.c. generator is generally adjusted by

(i) changing series field current

(ii) changing shunt field current

(iii) connecting it long-shunt

(iv) connecting it shod-shunt

Answer: (i) changing series field current

### 87. The d.c. generator that has poorest voltage is

(i) shunt generator

(ii) over-compounded generator

(iii) flat-compounded generator

(iv) series generator

Answer: (iv) series generator

### 88. If P is the number of poles of a generator and N is the armature speed in r.p.m., then frequency of magnetic reversals is

(i) f = NP/120

(ii) f = NP/60

(iii) f = NP/240

(iv) f = NP/30

Answer: (i) f = NP/120

### 89. If the value of shunt field resistance of a shunt generator is greater than the critical resistance, the generator will

(i) excite to full voltage

(ii) fail to excite

(iii) excite to one-half of full-voltage

(iv) none of the above

Answer: (ii) fail to excite

### 90. The no-load voltage of a generator is 240 V and rated-load voltage is 220 V. The voltage regulation of the generator is

(i) 4.5%

(ii) 11.3%

(iii) 2.8%

(iv) 9.1%

Answer: (iv) 9.1%

### 91. The O.C.C. of a d.c. generator is also called its ……. characteristic.

(i) internal

(ii) external

(iii) no-load saturation

(iv) performance

Answer: (iii) no-load saturation

### 92. The O.C.C. of a d.c. generator

(i) is similar for all types of generators

(ii) is different for different generators

(iii) may be same or different

(iv) none of the above

Answer: (i) is similar for all types of generators