TABLE I - COMPRESSOR ACCESSORY ELECTRICAL SERVICE SCHEDULE
Item
Voltage
Phase
Control Power and
120
1
60 Hz
Motors under 3/8 kW
Accessory Power
460
3
60 Hz
TABLE I - COMPRESSOR ACCESSORY ELECTRICAL SERVICE SCHEDULE
Item
Voltage
Phase
Control Power and
120
1
60 Hz
Motors under 1/2 hp
Accessory Power
460
3
60 Hz
2.3.5
Compressor Controls
Provide complete pneumatic load range control system with each compressor
with a manually selectable capability for two modes of load range control
as specified. Provide additional electrical, electro-pneumatic, or solid
state electronic controls for other specified control and monitor
functions. All controls shall conform to NEMA ICS 2 as selected by the
compressor manufacturer. Control system enclosure shall conform to NEMA
ICS 6. Controls shall be suitable for individual operation of the
compressor or parallel operation with one or more other compressors.
2.3.5.1
Two-Step Control Mode
The two-step control mode shall actuate the compressor suction inlet
control valve to either a full open position or to a full closed position
in accordance with specified, adjustable pressure settings. The pressure
settings shall be an adjustable band width plus and minus percentage of an
adjustable output gage pressure set point. The compressed air output gage
set point shall be adjustable in the range of 724 to 862 kPa 105 to 125 psig,
and the gage pressure sensor measurement for this set point shall be made
downstream of the aftercooler. The adjustable band width about the set
point shall be from plus or minus 2 1/2 percent to plus or minus 5 percent.
Controls shall close the compressor inlet valve at the high pressure limit
of the band width and simultaneously open a bypass vent valve which shall
also be provided. Controls shall open the compressor inlet valve at the
low pressure limit of the band width and simultaneously close the bypass
vent valve.
2.3.5.2
Dual Control Mode
A pressure regulation control mode shall be furnished to control compressor
output pressure to within plus or minus one percent of an adjustable output
pressure set point. Provide an adjustment range of 724 to 862 kPa 105 to
125 psig. When the compressor operates at capacities above surge limit
unload setting and below maximum flow stonewall conditions, the control
system shall throttle flow at the compressor suction inlet control valve in
response to increasing discharge pressure due to decreased demand for
compressed air. At lower demand, prior to reaching surge limit at a flow
capacity not more than 70 percent of guarantee point capacity, the
compressor shall unload by closing the compressor inlet suction control
SECTION 15213N
Page 15
Previous Page
