Ques. What precautions should be taken in starting a dynamotor?
Ans. The necessary precautions are, to have the poles strongly magnetized before passing current through the motor winding on the armature; to increase gradually the current through this winding, and not to close the generating circuit until normal conditions regarding speed, etc., are established in the motor circuit.
Ques. How is the current developed in the machine regulated?
Ans. It can be regulated by the introduction of resistance in one or the other of the armature circuits, or by a shifting of the brushes around the commutator.
Ques. Are dynamotors less efficient than motor generators of a similar type?
Ans. No, they are more efficient.
Ques. Why?
Ans. Because they have only one field circuit and at least one bearing less than a motor generator.
A motor generator has at least three bearings, and occasionally, four, where the set consists of two independent machines directly connected together.
Rotary Converters.—An important modification of the dynamotor is the rotary converter. This machine forms, as it were, a link between alternating and direct current systems, being in general a combination of an alternating current motor and a dynamo.