Зображення сторінки
PDF

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 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 magnetically 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; especial attention shall be given the insulation, protection and separation of contacts, binding posts and bared surfaces having extreme differences of potential in order to minimize the danger of accidental shocks, crosses, or grounds under normal conditions of operation; the dy

namo(s) shall be so designed and automatically regulated that the power will be automatically proportioned to the number of lamps burning at any time.

(See Note: p. 48, sec. 23.)

There shall be provided with each dynamo, in addition to the automatic regulator required above, one ampere meter for indicating the current supplied by the dynamo and graduated to read amperes; 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; one main switch; one pair of lightning arresters; and for the general installation one testing set capable of measuring up to ohms.

(See p. 61, sec. 34.)

66. Founda tlons.

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

single carbon )
double carbon >
triple carbon )

arc lamps of nominal candle-power.

Each lamp shall be provided with a switch by which it may be cut in or out of circuit; shall be regular in its feeding action; shall be free from hissing, flickering or flaming when provided with proper carbons; shall contain an efficient device which shall automatically cut out a lamp for any reason defective, without interfering with the operation of the lamps remaining in circuit; and shall be simple, strong, and durable in its mechanical construction.

[graphic]

hanger boards for inside use, each

hanger board to contain a switch by which the lamp may be cut entirely out of circuit.

71. Hoods. waterproof hoods, complete with

I hanger boards for outside use )
-< out-rigger attachments V
( cross-suspension attachments )

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

sets of carbons, a set consisting 74- carbons.

of one upper and one lower carbon.

(Seep. 51, sec. 25.)

(See p. 51, sec. 26.)

(See Note: p. 52, sec. 27.) 77. summary.

Each bidder shall fill out completely the following summary:

Number of dynamos ....

Trade number or designation . .

Rating in volts —

Rating in amperes

Capacity in c. p. lamps . .

Series or shunt wound . , . . —

H. P. required to be delivered at

pulley at full load . . .

75. Starting Plant and Instruction.

76. Renewal Parts.

SWITCHBOARD APPARATUS AND CONNECTIONS.

This contractor shall furnish and erect the following apparatus and material:

tokrrt comb"- One combination (material) switchboard plete' with a capacity for circuits, and provided with the necessary sockets, plugs, main and transfer cables, testing connections, and a suitable and convenient device for holding cables not in use. It shall be so arranged and marked that any circuit or series of circuits may be quickly connected with or disconnected from any dynamo with the least possible danger of short-circuits or error. Sockets shall be so designed that it is practically impossible to short-circuit, ground or receive a shock from them. All connections with the dynamo leads shall be easily accessible. All wires used in making connections shall have insulation. All plugs shall have well insulated wooden handles and the cables shall be covered with soft-rubber tubing

« НазадПродовжити »