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loss of the lead unit and decrement their rotation numbers. Number 2 becomes number 1, the new lead
unit, number 3 becomes number 2, etc. The former lead unit will become the last lag unit.
The transfer interval timer operates whenever a member is the lead (Seq 1) unit of the system. It will
continue to time out regardless of other units in the system. The remaining time is retained during power
interruptions. It is reset back to full value if the controller is in any mode other than Seq 1.
Other Sequencing Features -
Any air system will exhibit pressure differences from one point to the next.
Even a well designed multi-compressor installation will show 'minor' pressure variations between one
compressor's discharge point and another compressor's discharge. These points will also vary from the
actual system storage (normally the air storage receiver). The sequencing system is designed to tolerate
minor variations. The sequencing system will automatically adjust the system setpoint to maintain the
average system pressure. Overpressures within any member compressor are prevented locally, and
other members will load up to meet the demand. The dynamic setpoint control is completely automatic
and is continuously adjusted.
If airflow is restricted between the compressor units and the common storage, the 'minor' variations
described above become more significant. The pressure in the receiver will always be lower than that
sensed by the compressor system. The system will tolerate this, and will still maintain the average
pressure within limits. These restrictions may spread loading and unloading over several units, rather
than showing the strong preference to unload only the last loaded lag unit.
The Lag Start Delay timer of any member does not begin timing until the preceding member of the
system is loaded. This is particularly useful when starting up the system, as compressors will be started
one at a time. This sequenced starting also happens if the members are controlled by their remote
inputs. If programmed for automatic restart after power failure, the lead unit will be delayed by the
automatic restart delay, then each additional unit will be delayed by the lag start delay.
If automatic restart is enabled in a sequenced system, set all of the restart delay 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.
CONNECTION TO OTHER "AUTO SENTRY" CONTROLLED COMPRESSORS
The controller offers capabilities to communicate with other Gardner Denver compressors in a sequenced
system. Although the system ideally consists of a group of identical machines, there are some instances
where a mixed group may provide acceptable service.
When building a system with other units with "AUTO SENTRY ES+" controllers, set the "AUTO SENTRY
RS2000" for sequencing at the same baud rate as the larger controllers. Set all the companion ES+ units
for “LOAD-UNLOAD” operation. This will provide all of the performance described above.
Systems with mixed compressors are generally better served by splitting the system into two independent
parts. Each part should consist of a single compressor or a group of peer units, adjusted for the desired
operation.
CONNECTION TO EXTERNAL CONTROLS
The "AUTO SENTRY RS2000" controller offers interconnection points for external controls and
indicators. This allows simple connection to remote controls and indicators, or integration into any
plantwide controls system.
Remote On / Off
- Remote on-off control of the system requires only a simple two-wire control, with an
isolated contact suitable for 120 volts, 1 amp. This may be a switch, a timer contact, a relay contact, or a
PLC output. To connect, simply run the two wires to the control enclosure, remove the jumper between
terminal 5 and terminal 9 on the terminal strip, and connect the two wires to terminal 5 and terminal 9.
Summary of Contents for AUTO SENTRY RS2000
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