Section 2
SEQUENCING WITH
MULTIPLE CONTROLLERS
5
a. UNLOAD psi
b. LOAD psi
c. BAUD RATE (Supervisor II only). Baud Rate for Supervisor and WS is fixed
at 9600.
d. SEQUENCE mode (COM ID or HOURS)
e. LAST COM
f. LOWEST (minimum pressure before a machine is started)
g. RECOVER time (normally set at 10)
h. Leave ROTATE hours disabled except for the specific application described
in Section 2.8.
i. Set all sequence hour parameters the same unless it is desired to force
certain machines to initially run longer than others in the HOURS mode.
5. Start the machines for sequencing as described in Section 2.1. Machines will start
immediately if the P2 system pressure is low. On a fully pressurized system the
machines will go into a standby state until a demand is recognized.
2.5 SYSTEM OPERATION
The following example describes how machines are started, fully loaded and unloaded by
the sequencing mode selected. The Automatic mode provides the means for each
machine to stop by timing out on its unload timer when the sequencing order indicates
the machine is to be unloaded.
For this example three machines are in a system with the load pressure set at 100,
unload limit pressure at 110 psig (7.6 bar), lowest pressure limit at 90 psig (6.2 bar), and
Recovery Time at 10 seconds (default value). All machines are stopped.
1. When the pressure drops below 102 psig (7.6 bar) a timer starts counting down from
120 seconds, if the pressure continues to drop the timer will count down faster
(increments will be shorter).
2. When the timer expires or the pressure drops below 90 psig (6.2 bar) the first (or
next) machine in the sequence is started.
3. If the pressure does not go above 90 psig (6.2 bar) for 10 seconds (Recovery Time)
the second (or next) machine in the sequence will start. This process will continue
until all machines are started or loaded.
4. As machines are started and loaded, there will be only one machine that is
modulating, the others will be forced to "FULL LOAD". The modulating (trim)
machine will load at 2 psig (0.14 bar) above the load pressure parameter, 102 psig
(7.03 bar) in this example, and unload at 2 psig (0.14 bar) below unload pressure
parameter, 108 psig (7.4 bar) in this example. The reason for this narrow
load/unload band is to keep all machines from loading and unloading at the same
time.
5. If the pressure rises above the unload pressure -2 psig (0.14 bar) to 108 psig (7.4
bar) the trim machine will unload (display will read "UNLOADED") and the next
machine in the sequence will switch from full load to trim.
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