[2.2.4.5
Accessories
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NOTE: Electric-clock controller is an input
controller provided separately as an optional
addition to unit heaters. Delete this paragraph if
not required.
**************************************************************************
Provide electric-clock controller with self-starting synchronous motors and
snap acting switch, rated for 125 percent of the load which it controls.
Provide a 30-second time cycle with an infinitely adjustable "on-off"
period each cycle. Equip controller with external indicating knob for
manual adjustment from zero to 100 percent. If surface mounted, furnish
steel enclosure with a baked enamel finish over a corrosion-resistant
primer. If flush mounted, furnish galvanized steel enclosure with
knockouts for conduit in bottom and sides. Provide a connection wiring
diagram on the inside cover of the enclosure. Where loads exceed the
maximum available rating of controller, provide high duty-cycle contactors
serving as pilot devices.
]2.3
FAN
Provide [steel] [or] [aluminum] fans with ball or roller bearings for
motors over 0.09 kW 1/8 horsepower (hp) and sleeve bearings for motors 0.09
kW 1/8 hp and under. Provide sleeve bearings with oil reservoir, if not
permanently lubricated.
2.4
MOTOR AND STARTER
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NOTE: The motor control requirements should be
coordinated with the electrical section and will
depend on field conditions. The following types of
motor starters should be used as a guide only. When
electrical power circuits to which equipment are
connected are heavily loaded, the full
voltage-across line starting may result in excessive
voltage drop on the circuit.
Motor kW
Voltage
Type Starter
Up to 5 1/2
208-230
Across line magnetic
5 1/2 to 11
208-230
Across line magnetic,
part wind or wye delta
11 to 22 3/8
460
Across line magnetic part
wind or wye delta
Above 11
208-230
Part wind or wye delta
Above 22 3/8
460
Part wind or wye delta
Motor hp
Voltage
Type Starter
Up to 7-1/2
208-230
Across line magnetic
7-1/2 to 15
208-230
Across line magnetic,
part wind or wye delta
15 to 30
460
Across line magnetic part
wind or wye delta
Above 15
208-230
Part wind or wye delta
Above 30
460
Part wind or wye delta
SECTION 15760N
Page 13
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