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danger the insulation or decrease the efficiency of operation; shall not spark unduly with proper care of the commutator and adjustment of the brushes, nor under considerable variation of 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 both 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; if of the direct and constant-current
type | j- shall be so designed that
with the proper connections two or more may be operated successfully in series, so that with ordinary care and precaution any dynamo may be added to or taken from the circuit without in any manner affecting the efficient operation of the remainder, and with but a momentary fluctuation in the candle-power and steadiness of the lamps; if of the direct-current,
constant-potential type j j- shall be
so designed that with the proper connections two or more may be operated successfully in parallel so that with ordinary care and precaution any dynamo may be added to or taken from the circuit without in any manner affecting the operation of the dynamos remaining in circuit or causing any change in the candle-power of the lamps; and that when two or more are operating on the same circuit the load may be divided between them in proportion to their respective capacities under all conditions from no load to full load. The dynamo(s) shall be rated with such
margin of safety that j |^ey j- will not be
injured if subjected to an overload of
per cent, above such rating for a period of .
(See Note: p. 46, sec. 22.) 34-
shall be built by the of—,
laid , or of other material subject to
the approval of the j J£gTMg, [ andshall
be of sufficient length, width, and depth
to safely and firmly sustain j ^eir j
weight. The foundation(s) shall be capped with a framing of well-seasoned timber securely fastened thereto, the dynamo baseframe(s) 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 must be thoroughly insulated where it passes through them, and at all places liable to come in contact with the dynamo must 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 baseframe^) above the floor line will be .
35. inrtru- (See Note: p. 48, sec. 23.)
There shall be provided with each dynamo one voltmeter or pressure indicator which shall remain constantly in circuit so as to indicate at all times the pressure at the point to which it is connected; one brush jig for trimming the brushes; one insulating baseframe provided with rails and a suitable device for shifting the position of the dynamo to alter the belt tension; if of the constant-potential type, one hand regulator made entirely of incombustible material, a compensator or suitable balancing device for keeping the current in each circuit practically constant; if of the constant-current type a regulator for so controlling the potential as lights are turned on or off that the current shall not vary appreciably from its normal value under any condition of load. There shall be provided for each circuit one ampere meter for indicating the current in said circuit, one ground detector which shall continuously indicate the insulation from the ground maintained at both poles and approximately the distance of any ground from the station, and one pair of lighting arresters. There shall also be provided one testing set capable of measuring up to ohms.
This contractor shall carry to the j^taSKwi
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 ampere and no wire
smaller than B. & S. or B. W.
G. shall be used. All wires shall be in