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22. Foundations.

The dynamo(s) shall be rated with such

S

margin of safety that they shall not be injured if subjected to a temporary overload of per cent. above such rating.

(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)

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sufficient length, width and depth to safely

and firmly sustain{their weight.

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

purchaser. The height of the dynamo 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.

(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.

47

23. Instru

ments.

Switchboard.

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

25. Starting

struction.

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. W. G. shall be used. Regulator wires shall be covered with insulation, and shall be

B. & S. or

(cleated to the ceiling,

of

carried on insulators,
concealed in molding;

main wires shall be

{ bare copper wire supported or insulated

wire

on porcelain insulators.

carefully cleated to the ceiling, carried on porcelain insulators, concealed in molding consisting of a backing -thick and a capping

thick

wires of opposite
not less than —-

polarity being separated In no case shall insulated wires be carried in such proximity to heated surfaces, vapors, or air as to endanger their insulation.

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

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. Renewal 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 following summary:

Number of dynamos

Trade number or designation

Rating in volts

Rating in ampères

Shunt or compound

Make of lamp recommended for use. Dynamo capacity in c. p. lamps of the above make

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28. Switch

board.

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:

(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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