Series and parallel connections--coupling series dynamos in series; in parallel--equalizer--shunt dynamos in series; in parallel--switching dynamo into and out of parallel--to cut out a machine--dividing the lead--compound dynamos in series; in parallel--equalizer connection--switching a compound dynamo into and out of parallel--equalizing the load--shunt and compound dynamos in parallel.
DYNAMO FAILS TO EXCITE [611] to [622]
Various causes--brushes not properly adjusted--defective contacts--incorrect adjustment of regulators--speed too low--testing for break--insufficient residual magnetism; remedy--open circuits--test for field circuit breakers--probable location of breaks--Watson armature discs--Fort Wayne commutator truing device--short circuits--Watson armature--wrong connections--reversed field magnetism.
ARMATURE TROUBLES [623] to [634]
Causes--how avoided--various faults--short circuit in individual coils--location of faulty coil--test for break in armature lead--bar to bar test for open or short circuit in coil or between segments--short circuits between adjacent coils--alternate bar test for short circuits between sections--short circuits between sections through frame or core of armature; between sections through binding wires--partial short circuits in armatures--method of testing for breaks--burning of armature coils--Watson field coils--grounds in armatures--method of locating grounded armature coil--magneto test for grounded armatures--method of binding armature winding--breaks in armature circuit.
CARE OF THE COMMUTATOR AND BRUSHES [635] to [652]
Conditions for satisfactory operation--oil for commutator--attention to brushes--Bissell brush gear--two kinds of sparking--commutator clamp--causes of sparking--bad adjustment of brushes--rocking--bad condition of brushes--brushes making bad contact--bad condition of commutator--detection of untrue commutator--high segments--"flats"--causes of flats; remedy--method of repairing broken joint between commutator segment and lug--segments loose or knocked in--how to re-turn a commutator--Bissell commutators--overload of dynamo--method of repairing large hole burned in two adjacent bars of a commutator--operating dynamos with metal brushes--indication of excessive voltage--method of smoothing commutator with a stone--causes of excessive voltage--loose connections, terminals, etc.,--breaks in armature circuit--sandpaper holder for commutator--short circuits, in armature circuits; in field--breaks in field--sandpaper block--short circuits in commutator.
Various causes--how detected--procedure--heating, of connections; of brushes, commutator and armature--excessive heating--ventilated commutator--self-oiling bearing--some causes of hot bearing--effect of hot bearings--points relating to hot bearings--operation above rated voltage and below normal speed--forced system of lubrication--heating of field magnets--causes of eddy currents in pole pieces--detection of moisture in field coils--indication of short circuits in field coils.