Зображення сторінки
PDF
ePub

namo unless lights are operated therefrom, in which case a switch and cut-out shall be placed in the main circuit before branching off to the various dynamos.

There shall be provided the following 46. Convertnumbers and sizes of converters:

ers.

[blocks in formation]

Each converter shall reduce the voltage on the primary circuit to volts on the secondary circuit; shall have its capacity plainly marked upon it; and shall be provided with a separate fusebox which shall be so arranged that when replacing fuses or otherwise working about the converter the primary circuit may be opened.

[blocks in formation]

50. Summary. (See Note: p. 52, sec. 27.)

51. Switchboard.

52. Switchboard Appa

ratus and

Each bidder shall fill out completely

the following summary:

Number of alternators

Trade number or designation
Number of exciters

Trade number or designation

Rating of alternators in volts

[ocr errors]
[ocr errors]
[merged small][ocr errors][merged small][merged small]

H. P. required to be delivered at

the pulley at full load

(See p. 53, sec. 28.)

[ocr errors]
[ocr errors]

There shall be placed upon this switchConnections. board, in addition to the dynamo regulating apparatus, such switches, cut-outs and other appliances as are necessary for the proper and convenient manipulation of the circuits, such appliances to be

named by each bidder in his proposal.

The appliances and connections shall be such as will permit the operation of any dynamo on any circuit or number of circuits, and the cutting in or out of any dynamo or circuit with certainty and rapidity without in any manner affecting the operation of other dynamos or circuits. (They shall also be arranged in such manner as to render it possible to connect two dynamos in parallel by an arrangement of switches or combination of circuits.) (For switchboard connections see secs. 30 and 31, pp. 55 and 56.)

(See p. 57, sec. 32.)

53. Circuits.

Alternating Current or Direct Current
System, with the Parallel System of
Distribution.

This contractor shall furnish, and, unless otherwise specified, erect the following apparatus and material:

54. Dynamo(8). (See Note: p. 43, sec. 21.)

A dynamo capacity of, as nearly as possible, kilowatts. (The number of dynamos shall not be less than

[ocr errors][merged small]

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 insula

tion 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

« НазадПродовжити »