CHAPTER I THE OPERATION AND CARE OF SMALL ELECTRICAL MACHINERY As the majority of users of small electrical machinery are not familiar with the best methods employed to keep the machines in good running order and repair, the author aims to present a few practical suggestions, to be of some help in the making of necessary repairs, locating troubles, and removing the causes. The dynamo or motor should he installed in a dry place, and under no circumstances should water be allowed to come in contact with the machine. Excessive dampness always causes trouble, and this point should be guarded against. The machine shogld be well ventilated, and kept free from dust as much as possible, Before starting a new machine, see that the bearings are well fllled with good oil, and that the shaft turns freely in the bearings. The oil-rings should turn with the shaft, and not stick, as the lubrication of the bearings depends upon the rings working right. This is important and should be carefuIly matched. If the machine is belt driven, the belt should not be too tight, as this will cause undue wear on the bearing and may cause heating also. Always provide soIid foundations or supports for the machine to rest on. Keep the machine cool, dry and clean, and very little trouble will result in its operation in general. Then a new machine is installed and wired up, the connections should be carefully checked over to see whether they correspond with the diagram of connections sent wlth the machine. If this is found to be correct, and the nachine refuses to act properly, the cause of the trouble should at once be located and the difficulty removed before going further. Troubles in the Field Coils First we will consider the troubles that may exist in the Aeld coils, and how to proceed to correct them. If, on running a machine for some time, the field coils all become hot, the voltage may be too high and should be reduced to normal if only a part of the coils becomes hot, it will usually be found that a connection exists between the coils and the frame of the machine called ground, which when found should be insulated with mica or paper. Sometimes it will be found that some of the coils are cold while the remainder are excessively hot, and the cause of this is a short circuit in the cold coiIs, which means that the current is not passing through the coils. Test out the coils separately with a magneto or battery, and when the defective coil is found, it should be repaired by reinsulating it.................