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sulated with ;shall be run ;when

of opposite polarity shall be separated at

least ;and where crossing each other,

wires of other circuits, or passing near metal pipes, girders, etc., shall be further protected by . In no case shall insulated wires be carried in such proximity to heated surfaces, vapors or air as to endanger their insulation.

SLffl?J- (See p. 51, sec. 25.)

atruction.

38. Renewal (See p. 51, sec. 26.)

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

Each bidder shall fill out completely the following summary:

Number of dynamos

Trade number or designation .

Rating in volts

Rating in amperes

Direct or alternating current . .

Constant or varying current . . —

Constant or varying potential . .

Series, shunt, compound, self or

separately excited

Rating of exciter in volts . . .

Rating of exciter in amperes . .

Trade number or designation . .

Regulation by hand or automatic

Number of fully loaded circuits pos-
sible to operate per dynamo .

Volts per c. p. lamp . . .

Amperes per c. p. lamp . .

H. P. required to be delivered at

the pulley at full load . . .

(See p. 53, sec. 28.) «>. ^witch

There shall be placed upon this switch- «• Switchboard Appa

board, in addition to all the dynamo regu- confections, lating 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. For systems operating dynamos and circuits in parallel, the appliances and connections shall be such as will permit adding to or taking from the circuit any

dynamo without in any manner affecting the operation of the dynamos remaining in circuit or the candle-power of the lamps, and will permit the cutting in or out of any circuit without affecting the stability of other circuits. For systems operating one dynamo for each circuit or series of circuits the connections shall be such as will permit any circuit to be connected to or disconnected from any dynamo with certainty and rapidity. (For switchboard connections see sees. 30 and 31, pp. 55 and 56.

48. circuits. (See p. 57, sec. 32.)

Constant Potential, Alternating Current
System.

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

(See Note: p. 43, sec. 21.) 43. Dynamow.

constant potential, alternating

current dynamo(s) (each) having a capacity of kilowatts. The maximum

voltage at the terminals of the dynamo(s) shall not exceed volts.

The dynamo(s) shall be of the latest and most efficient pattern; mounted on 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 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 highspeed, automatic cut-off engines belted direct; shall be supplied 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; all contacts, brushes, binding posts, etc., shall be so placed and protected that there is the least possible danger of receiving a shock. The dynamo(s) shall be rated with such

margin of safety that j ^ ey | will not be

injured if subjected to an overload of

per cent. above such rating for a period of ;if self-exciting the coils furnishing the exciting current, and the commutator shall be so insulated and protected

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