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The dynamo(s) shall be rated vrith such margin of safety that they shall not be

} injured if subjected to a temporary overload of per cent. above such rating.

22. Founda

tious.

(Note.- In the specification for foundations it should be borne in mind that a dynamo is not subject to vibration if its armature is properly balanced, nor to the strains and shocks due to the movement of rapidly reciprocating parts, it is therefore only necessary to provide such foundation as will amply sustain its weight and resist the belt strain.)

The foundation(s) for the(se) dynamo(s) shall be built by the contractor

of

purchasers laid

--, or of other material subject to the approval of the engineer, and shall be of

architect, sufficient length, width and depth to safely

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and firmly sustain { their

S their weight.

}

S All necessary excavating or filling, and the removal of all débris shall be done by the contractor.

The height of the dynamo purchaser. S base-frame(s) above the ground will be -

The dynamo base-frame(s) shall be firmly and securely fastened to the(se) foundation(s) in such a way as to prevent lateral motion in either direction, and to give an even bearing surface at every point.

23. Instru

ments.

(Note.—This specification simply provides for such instruments as it is customary to furnish with a dynamo; if extra instruments are desired, such as portable voltmeters, portable ammeters, testing sets, etc., they should be distinctly specified, as well as the make if a particular kind is preferred.)

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 and graduated to read ampères; 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 which shall be so constructed that the scale is plainly visible at a distance of at least - ; 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; and one headboard switch for cutting off the current at the dynamo itself. There shall also be provided for the installation -- ground detector(s), which shall continuously indicate the insulation from the ground maintained on both sides throughout the system, and lighting arresters of the most efficient type known.

(Note.-In the case of compound dynamos 24. Cables to operating in parallel the equalizing wire may often more conveniently be carried direct

Switchboard.

from dynamo to dynamo, in which case this contractor should furnish and connect a suitable equalizing switch at each dynamo.)

This contractor shall carry to the switchboard location at all regulator 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. Regulator wires shall be covered with

insulation, and shall be
cleated to the ceiling,
carried on insulators, main wires shall be
concealed in molding;
copper

or
on porcelain insulators.
s carefully cleated to the ceiling,

carried on porcelain insulators,
wire concealed in 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.

of

25. Starting

When the plant shall be ready for operation Plant and in the dynamo(s) shall be run for a period of

days by competent engineers furnished by the contractor. All oil, waste, power, etc., to be furnished by (the purchaser). This con

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tractor shall also give all necessary instruction to the engineer of the purchaser) for the proper care, maintenance, and operation of the dynamo(s), such instruction to be given during the trial period stipulated above.

Parts.

This contractor shall furnish such renewal 26. Reneral parts as it is advisable to keep on hand, adding hereto an itemized list of same.

(Note.-The object of this summary is to 27. Summary. present in a concise, tabulated form, the essential data concerning the apparatus to be supplied, thus enabling the different bids to be easily and quickly compared. For complete plants a single form, systematically arranged, will be found extremely convenient both in making comparisons and in being able to see at a glance just what apparatus and appliances are called for, thus constituting a check on the specifications themselves.)

Each bidder shall fill out completely the fol-
lowing summary:
Number of dynamos
Trade number or designation
Rating in volts
Rating in ampères
Shunt or compound
Make of lamp recommended for use .

i Dynamo capacity in C. p. lamps of

the above make Speed Size of pulleys

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H. P. required to be delivered at the

pulley at full load with no loss in
the feeders

Switchboard and Appliances. This contractor shall furnish and erect the following apparatus and material:

28. Switch

boaril.

(Note.-In plants of any considerable size the switchboard specification is an extremely important one. Its general characteristics will be determined by questions of purpose, economy, utility, available space, beauty, etc., but the details of material, method of wiring, attachment of instruments, location, number of switchboards, etc., demand the most careful study. It may be advisable in one instance to have a single switchboard controlling everything from a single centre, in another to have a dynamo switchboard and a separate circuit switchboard, while in yet another to even divide the dynamo switchboard into two or more parts and to have several circuit switchboards. In determining the location of switchboards, not only should questions of convenience be considered, but also questions of its relation to economy in the wiring; the example given on p. 22 illustrates this. Upon the arrangement of the instruments will depend the facility and certainty with which they may be operated.)

The switchboard shall be made of neatly and substantially built, of sufficient

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