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54. Dynamo (s).
A dynamo capacity of, as nearly as possi ble, –, -– c. p. incandescent lamps. (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 surface of 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 so designed that the power required will be automatically proportioned to the number and candle power of the lamps burning at any time; and shall be rated
with such margin of safety that } they | will
overload of —— per cent. above } | IlOI'
required for the operation of the dynamo (s)
the same conditions.
(See Note: p. 44, sec. 22.)
approval of the } . | and shall be of
sufficient length, width, and depth to safely
and firmly sustain jor | 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 débris shall be done by the
t - }. The height of the dynamo
baseframe(s) above the ground will be —.
* (See Note: p. 45, sec. 23.) There shall be provided with each dynamo One hand regulator for adjusting the pressure, made entirely of incombustible material; one ampère meter for indicating the current supplied by the dynamo; one voltmeter or pres
sure indicator, which shall remain constantly
For alternating systems there shall be pro-57. Converters. vided the following numbers and sizes of con- to . . verters: Number. Sizes.
58. Cables to Switchboard.
(See Note: p. 45, sec. 24.) This contractor shall carry to the switchboard location at — all regulator, exciter, auxiliary, and main wires, leaving the ends coiled up neatly, properly tagged, and sufficiently long to make the necessary switchboard connections. All main wires shall have a capacity of at least C. M. per ampère, and no wire smaller than B. & S. Or B. W. G. shall be used. All regulator, exciter. and for systems carrying over —— volts all auxiliary and main wires, shall be insulated with —; all wires of systems carrying over — volts shall be run —; where of opposite polarity shall be separated at least —; and where crossing each other, wires of other circuits or passing near metal pipes, girders, etc., shall be further protected by ——. For systems carrying less than —— volts the main wires shall be of } bare copper wire supported on porcelain insulators. carefully cleated to the ceiling, carried on porcelain insulators, concealed in a molding consisting of a backing — thick and a | capping — thick wires of opposite polarity being separated not less than —. In no case shall insulated wires be carried in such proximity to heated surfaces, vapors, or air as to endanger their insulation.