13-9-653 Page 11
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+ controlled system is the most fully-featured, functionally-complete available today.
Compressor system -
A proper sequencing installation requires two or more Gardner Denver rotary air compressors
complete with controllers, piped into a common air system, interconnected as described above. For best
performance, connect the units directly to a common header and receiver, without any intervening dryers, filters, or
other restrictions. If any equipment must be installed on individual compressors, select equipment with minimum
pressure drop. If filters are installed, establish a maintenance procedure to prevent clogging filters from upsetting the
system. There should be no check valves or other devices which isolate a member from the air system. During
operation, be sure that any unit is taken out of the sequence mode before closing its service valve.
The receiver should also be sized to prevent excessive drops or rapid rises in pressures during the operation as
described below. Note that "receiver" really applies to the entire storage volume of a physical receiver and the
volume of the air distribution throughout the plant. Modulating systems work best when the receiver is at least one
gallon for the rated CFM of a member compressor in the system (the largest if they differ). If the system is operated
load-unload, larger volume or wider differential may be needed to prevent unnecessary starts or rapid compressor
cycles. Note that when demand exceeds the capacity of the running unit(s), there will be a delay until the next unit
starts and delivers additional air. The stored air serves the plant during this period. With a properly sized receiver,
pressure changes on a receiver gauge should be very slow and gradual.
All standard practices common to sound air compressor installations such as proper sizing of piping, proper electrical
supply and conductor sizing, and grounding are to be observed. Run the compressors in the system in Automatic
mode for at least one week to evaluate system performance.
Sequencing installation -
Once the compressor system is set up, sequencing compressors with the controller is as
simple as plugging in a telephone to a wall jack. The only item required to make the system functional is a cable
similar to a phone cable. The cable and connectors used in kit part number 200EAP752 have been specially
selected to meet the needs of an industrial application. One less cable than the number of compressors to be
sequenced is required. For example, to sequence four compressors, three cables are required.
The serial communications interface meets RS-485 standards, the most widely used interface in harsh, industrial
environments today. However, the communications cables should be routed through metallic conduit to provide them
with both mechanical protection and electromagnetic shielding. Do not run the communications cable in a conduit
with other wiring.
Each controller has two modular jacks which accept RJ-12 telephone plugs, located on the top of the controller case.
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, the pigtail plug must be disconnected on
all controllers except the two at each end of the communications line. The order of interconnection 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 it to 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.
Program all members of the system, as described in the programming procedure on previous pages. All adjustments
should be identical for each member, except for unit number. The sequencing system will make any necessary
adjustments to the setpoints to properly run the compressed air system.
Operation -
Press the [SEQUENCE] key on each of the compressors to start operation of the sequenced system.
Once this is done, the member controllers will operate the compressor units as required to maintain the plant
pressure between the programmed Set and Reset Pressures, for demands from 0 CFM up to the capacity of the
system.
While operating, each controller will display a sequence number. As demand requires, the units will start and load in
order, starting with sequence number 1 (lead unit). As demand falls, the higher sequence number units (lag units)
will modulate, unload, and stop.
If any member of the system is taken out of sequence mode for any reason, other units with higher sequence
numbers will automatically promote as required. Sequence numbers will start with 1, and will be assigned on other
units up to the number of compressors in the system. This feature makes the system completely tolerant of any
manual or protective stopping of any member.
Summary of Contents for AUTO SENTRY-ES+
Page 19: ...13 9 653 Page 15 Figure 1 3 WIRING DIAGRAM 216EAP546 B Ref Drawing Page 1 of 2...
Page 20: ...13 9 653 Page 16 216EAP546 B Ref Drawing Page 2 of 2...
Page 21: ...13 9 653 Page 17 Figure 1 4 WIRING DIAGRAM 304EBH546 C Ref Drawing Page 1 of 2...
Page 22: ...13 9 653 Page 18 304EBH546 C Ref Drawing Page 2 of 2...
Page 23: ...13 9 653 Page 19 Figure 1 5 WIRING DIAGRAM 301EAQ546 B Ref Drawing Page 1 of 2...
Page 24: ...13 9 653 Page 20 301EAQ546 B Ref Drawing Page 2 of 2...