Section 2
SUPERVISOR II SEQUENCING
12
Decisions to load, unload or start another machine are deferred until the timer reaches the
RECOVER time setpoint. Note that the timer starts when a machine is added or taken away
from the system. If the pressure recovers within the RECOVER time, and then at a later time
the pressure drops below the Trim Low setpoint, another machine will load immediately. The
shorter the recovery time the more responsive the system to load changes, but the less
energy efficient it is because machines may not shut off as often. The more often a machine
loads the less likely it is to stay unloaded and shut off after the Unload timer expires. The
RECOVER TIME has a default value of 10 sec. and may be adjusted from 2 to 59 sec.
In the following discussion 'highest' refers to the machine with the highest SEQ HRS or
COM ID and 'lowest' refers to the machine with the lowest SEQ HRS or COM ID.
The following rules are used to load. unload and start :
1. Only the highest loaded machine will trim; the rest will be forced to full load.
2. The trim machine will unload when the line pressure rises above the Trim High setpoint.
The next highest loaded machine will then become the trim machine. If pressure remains
above the Trim High setpoint, the new Trim machine will unload after Recovery Time
expires. This process will continue until only enough machines are running and loaded
to maintain proper system pressure.
3. The lowest unloaded machine will load (trim) when the line pressure drops below the Trim
Low setpoint. If the pressure remains below the Trim Low setpoint the next Unloaded or
Sequence Stopped machine will load or start after the Recovery Timer expires. This
process will continue until only enough machines are running and loaded to maintain
proper system pressure.
4. The lowest stopped machine will start when the line pressure drops below the Trim Low
set point, and after a variable time out period. This time out is dependent on how far the
line pressure is below the Trim Low set point. The farther below the set point the shorter
the time to start.
5. The lowest stopped machine will override the above variable time out feature and start
when the line pressure drops below the Lowest Pressure set point, and after the recov-
ery timer expires.
Changing Sequence Parameters
To change parameters, push the program key until the top line of the display identifies the
parameter to be changed. The up arrow and logo keys will increment the parameter value
the lamp test will decrement. To save the changed value the program key must be pushed.
The next parameter will then be displayed.
The following parameters may need to be changed for sequencing:
COM NUM - Must be unique for every machine in the system. If there are three machines
in a system, for example, they must be numbered 1, 2 and 3.
BAUD RATE - Serial communications baud rate, almost always set to 9600.
LAST COM - Set to total number of machines in a system.
LOWEST - This should be set to the lowest allowable pressure before a machine has to
start. Normally this is 5 to 10 psi (.3 to. 7 bar) below the load pressure. If the system pres-
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