LARGE if estimated volume is greater than 1.0
gallon per CFM.
~
This setting is not critical. When set to
its most appropriate value, the con-
troller will maintain discharge at the
closest possible value. If not set cor-
rectly, pressure will vary from the de-
sired setpoint to a somewhat greater
degree but the compressor and its
components will not be adversely af-
fected.
27. The top line displays “REMOVE SYS PRESS.
The bottom line displays the current pressure be-
ing sensed at the package discharge. At this point
steps must be taken to ensure that system pres-
sure is really zero psig. Remove the line to the
system pressure transducer. Pressing [ENTER]
will now cause the “AUTO SENTRY-ES to cali-
brate the transducer output to zero PSIG. Ob-
viously, pressure measurement errors will occur if
‘zeroing’ is done with pressure at the transducer.
If large errors are detected, the controller will de-
mand that the transducer be checked.
28. The top line shows "REMOVE RES PRESS. The
bottom line displays the current pressure being
sensed in the reservoir. The reservoir pressure
transducer may now be ‘zeroed’ by following the
steps outlined in 27 above.
29. The display now reads “PRESS CNST RUN TO
JOG MOTOR,” Press the [CONSTANT RUN] key
to briefly energize the starters, and rotate the
compressor 1/4 to 1-1/2 revolutions to allow a
rotation check, This is limited to three tests.
30. This completes the programming and setup pro-
cedures for the “AUTO SENTRY-ES controller.
Press the [STOP/RESET] key to return the com-
pressor to the READY state.
SEQUENCING COMPRESSORS WITH THE AUTO
SENTRY-ES
Sequencing compressors with the AUTO SENTRY-
ES controller is as simple as plugging in a telephone to
a wall jack. The only item required to make the system
functional is a standard telephone cable similar to
cables that connect nearly every telephone to its wall
jack. One less cable than the number of compressors
to be sequenced is required. For example, four com-
pressors require three cables. A kit, 200 EAP752, is
13-9/1
0-841
available that contains all material needed to sequence
up to five compressors. This kit contains 500 feet of
cable, eight modular connectors, and a crimping tool to
install the connectors. Note that this cable is designed
specifically for this type of communication, and is a
higher grade than most standard phone cables.
In spite of the fact that it is a standard feature and its
inherent installation simplicity, the sequencing function
of a multi-compressor “AUTO SENTRY-ES system is
the most fully featured, functionally complete available
today.
Installation
A proper sequencing installation requires two or more
Gardner Denver rotary air compressors complete with
“AUTO SENTRY-ES controllers, piped into a com-
mon air system, interconnected as described above.
For best performance, pipe the units directly to the re-
ceiver, without any intervening check valves, dryers, or
other restrictions. Size the receiver to prevent exces-
sive drops or rapid rises in pressures during the opera-
tion as described below. All standard practices com-
mon to sound air compressor installations such as
proper sizing of discharge piping, proper electrical sup-
ply and conductor sizing, and grounding are to be ob-
served. The serial communications interface meets
RS-485 standard. This is the most widely used inter-
face in harsh, industrial environments today. However,
communications cables should be routed through me-
tallic conduit to provide them with both mechanical
protection and electromagnetic shielding.
Each control circuit board has two modular jacks that
accept RJ-12 telephone plugs, One jack is vacant; the
other has a short pigtail plugged into it. To interconnect
two compressors, plug the cable into the vacant jack on
each controller. For installations of more than two
units, disconnect the pigtail plug on all controllers ex-
cept the two at each end of the line. The order of inter-
connection has no effect on the system operation. The
following conditions are necessary and sufficient for
proper operation:
1, Every compressor must have a cable connecting
itto another compressor. One less cable than the
number of units sequenced must be used.
2. Each board that has only one cable connected to
it must have its pigtail plugged into the unused
jack. All installations will have two such units.
Operation
1. ESTABLISHING THE INITIAL SEQUENCE
Operation of compressors in sequence requires only a
press of the ‘sequence’ key on each compressor in the
system. Since the sequencing algorithm includes pro-
visions for automatic replacement of a failed master or
‘lead’ compressor, it is important for the operator to be
aware of the hierarchy of events when starting the sys-
tem.
Page 24
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