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SECOND
After the compressor has started and reached the off-line
setting and has unloaded, timer “B” requires the unit to
run unloaded for a period of time that the operator can
adjust between 2 and 60 minutes.
The setting of timer “B” is part of the options setpoint
routine and the timer cancels any accumulated time if the
compressor reloads before the timer cycle has finished.
An important point... This unloaded run time may, or may
not, be included in the mandatory 10 minute run time
used to cool the motor windings.
When the compressor has completed the settings of both
timer “A” and timer “B”, the Intellisys controller stops the
compressor and displays “STOPPED IN AUTO
RESTART.”
Pressure sensor 4APT continues to monitor the package
discharge pressure and sends information to the
controller which automatically restarts the compressor
when the pressure falls to the on-line setting.
An advantage to this method of automatic start/stop
control is allowing the compressor to stop much sooner
in certain situations and timer settings, thereby reducing
power costs.
Some Examples of Operation
EXAMPLE 1
The operator selects an unloaded run time of 2 minutes
in the OPTION routine and starts the compressor.The
unit runs loaded for 8 minutes, unloads and then runs
unloaded for two more minutes.
The total running time is 10 minutes which satisfies timer
“A” plus the unit ran two minutes unloaded which also
satisfies timer “B,” therefore, the unit stops automatically.
This example shows how timer “B” can sometimes be
included within the timer “A” interval. Think of the two
timers as running parallel.
EXAMPLE 2
The operator selects an unloaded run time of 3 minutes
in the OPTION routine and starts the compressor.The
unit runs loaded for 10 minutes and then unloads.
At this point, timer “A” has been satisfied but timer “B” still
wants the compressor to run unloaded 3 more minutes
before allowing an automatic stop.
The total run time for this example will be 13 minutes.
Remember.... If the unit reloads before timer “B” finishes
the 3 minute setting, the partial time is canceled and
timer “B” must restart the 3 minute cycle when the
compressor unloads again.