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Current limiting -
Current limiting is available when a controller is used on a compressor unit with TurnValve control
and has current monitoring installed. This is based on the motor service factor amps programmed above.
On units with TurnValves, the controller will unload as required to prevent operation above the programmed service
factor amps. This continues operation of the compressor at reduced delivery, but within the programmed limit. This
limiting will occur in either the modulating or the load-unload mode of operation.
This feature takes control only if operating conditions are outside of the compressor unit's design range. Low
operating voltage, in particular, can cause high amp draw. This will heat the motor beyond its design, and will
normally trip the overload relay to prevent motor failure. The controller, however, will automatically reduce the
delivery to continue operation within design limits. If severe conditions persist, the controller will display "
HIGH
MOTOR AMPS
."
This feature is also coordinated with the controller sequencing controls. During low voltage conditions, lead units will
operate only up to their limits. If necessary, another compressor will start to meet the air demand.
Auto restart after power failure -
The controller normally displays
"SHUTDOWN - POWER FAILURE"
after power
has been interrupted and restored. Press the [STOP / RESET] key and select an operating mode to restart the
compressor.
If programmed for automatic restart, the controller pauses and begins counting down when power is restored. This
time is adjustable in the programming steps noted above. This must be at least several seconds, but may be set
longer to allow other plant loads to start up first. After the countdown is complete, the controller resumes the mode of
operation prior to the power interruption.
If this is enabled in a sequenced system, set all of the timers to the same value. All controllers will then resume the
same sequence numbers which they had prior to the interruption. The sequence controls will start the lead unit after
the start timer countdown, and add units individually as required, based on the lag start delay.
SEQUENCING COMPRESSORS WITH THE
"AUTO SENTRY
®
-ES+"
General -
The sequencing mode is used to operate multiple compressors in a common plant air system. The
individual units operate similarly to operation in the automatic mode, except that the setpoints are under control of the
sequencing system. This system is actually distributed among the individual controllers and compressor units, with
communications between them to keep the system coordinated. Sequencing is intended to start, run, unload,
blowdown, and stop compressors in response to changes in demand during the day or week.
The controller is designed for systems of two through eight compressors piped into a common air receiver for
distribution to the plant. In any such system, the receiver is an important part of the application; it supplies air to the
plant and allows compressor units to be unloaded and stopped. This stored reserve eliminates the need to operate
"spinning reserve" of unloaded compressors. This storage may be an air receiver, or may be the volume of air in a
large distribution system. In either case, the compressors must be piped to this volume with a minimum of restriction.
The control system will operate only as many compressors as are needed to supply the CFM demand of the plant,
and to maintain the compressor system pressure between the SET and RESET pressures programmed into the
controllers.
NOTICE
Though similar in operation and installation, this sequencing system is designed to take
advantage of all the internal features of the controller. Communication cables should not be
connected to compressor units with controller parts numbers 201EAP1173 OR 202EAP1173.
Multiple compressors with each type controller may be operated as independent groups piped
to the same plant demand.
Auto Sentry ES+ and RS2000 Controllers may be combined into a system. In the ES+ adjustments, adjust set
pressure and reset pressure equal to the load and unload pressures of the RS2000. Adjust the IV control mode to
Load-Unload.
The controllers are completely set up to operate this system. The only required additional part is the cable which
runs from controller to controller. A kit, part number 200EAP752, is available which 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.
Summary of Contents for AUTO SENTRY-ES+
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