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Alternating Current or Direct Current
This contractor shall furnish, and, unless otherwise specified, erect the following apparatus and material:
54. Dynamo(a). (See Note: p. 43, sec. 21.)
A dynamo capacity of, as nearly as possible, kilowatts. (The number of dynamos shall not be less than
, nor more than .)
The dynamo (s) shall be of the latest and most efficient pattern; shall be mounted upon a base provided with an adjustable belt tightener so that the belt may be tightened while in operation; capable of operating under full load for
consecutive hours without increasing
the temperature of any part, especially the armature, fields, and commutator, to such a degree as to endanger the insulation or decrease the efficiency of operation; shall not spark appreciably with proper care of the commutator and adjustment of the brushes, nor under considerable variation of the load; shall have an insulation resistance of not less than
ohms between all parts insulated
from each other; shall be adapted to operate at such speed as will allow the use of high-speed, automatic cut-off engines belted direct; shall be provided with efficient oiling devices; the armature shall be balanced electrically and mechanically so that there will be no tendency to spring the shaft, or to draw the armature toward either bearing so as to cause excessive friction and heating, and no vibration; all contacts, binding posts, brushes, etc., having considerable differences of potential between them shall be so placed and protected that the danger of receiving a shock is the least possible; armature conductors shall be so securely attached to the armature as to - preclude any possibility of their being
dragged from their proper position under normal conditions of operation; all coils, connections, commutators, brushes, etc., belonging to different circuits shall be so insulated and protected that it will be impossible under the ordinary conditions of operation to cross or ground them; the dynamo(s) shall be rated with such margin of safety that j j- will not be injured if subjected to an over-load of per
cent, above j jjg6"" \ normal rating for a
period of ;'if(an) auxiliary dynamo(s)
| | re^uire<i for tne operation of the dynamo(s) specified above j -1^iey j- shall be subject to the same conditions.
55- t£°uBnda- (See Note: p. 46, sec. 22.)
The foundation(s) for the(se) dynamo(s)
shall be built by the j \ ef—,
laid , or of other material subject to
the approval of the j JJgW [ and shall be of sufficient length, width and depth to safely and firmly sustain j ^eir | weight.
For dynamos operating at voltages below the baseframe may be firmly
and securely fastened directly on the foundation. For dynamos operating at
voltages above the foundation shall
be capped with a framing of well-seasoned timber securely fastened thereto, the baseframe being securely fastened to the framing or to the foundation through the framing; both framing and baseframe being secured in such a manner as to prevent lateral motion in either direction, and to give an even bearing surface at every point.
If metal is used to fasten framing or baseframe to the foundation it shall be thoroughly insulated where it passes through them and at all places liable to come in contact with the dynamo shall be countersunk and covered with a moisture-proof insulating compound.
All necessary excavating and filling, and the removal of all debris shall be
done by the | £££££ } who shall also
restore the floor in the following manner: .
The height of the dynamo base-frame(s) above the floor line will be .
56. instru. (See Note: p. 48, sec 23.)
There shall be provided with each dynamo one hand regulator for adjusting the pressure, made entirely of incombustible material; one ampere meter for indicating the current supplied by the dynamo; one voltmeter or pressure-indicator which shall remain constantly in circuit so as to indicate continuously the pressure at the point to which it is connected, and shall be so constructed that the scale is plainly visible at a distance of at least ;one insulating baseframe provided with rails and a suitable device for shifting the position of the dynamo to alter the belt tension; there