Emerson Vilter PLC, Operation Manual

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Section 2 • Operational Descriptions
Blower Package PLC Operation Manual •Vilter/Emerson • 35391BLP
Operational Descriptions and
Diagrams
CONFIGURATION OF THE BLOWER PACKAGE
The Blower package PLC can control up to 4 blowers.
The blowers can be independently con
fi gured to run on
a fi xed speed setpoint, PID Control (variable speed), or
taken out of service:
• Fixed Speed: In auto mode, individual blowers can be
con fi gured to run on 1 of 4 fi xed speeds.
• Variable Speed: The individual blower’s speed will
be controlled by a PID controller to hold a suction or
discharge pressure setpoint. If multiple blowers are
con
fi gured to run on PID control, all will run off of a
common speed command from the PID controller.
• Out of Service: Individual blowers may be taken out
of service for demand considerations or mainte-
nance. When a blower is out of service, alarms, trips,
and status messages speci
fi c to that blower will not
be generated.
Additionally, individual blowers may be enabled and dis-
abled “on the
fl y,” either locally or remotely (by commu-
nications) without having to take them out of service.
Functions such as anti-recycle, and selected alarms and
trips are blower speci
fi c, meaning if active, they apply
only to the affected blower. This way if one blower trips
or is in anti-recycle, the other blowers are allowed to run.
At start, the blowers may be con
fi gured to start offset
from each other, to lessen the burden on the electrical
infrastructure due to motor inrush.
STARTING OF THE BLOWER/PERMISSIVES
To run the blower package, it must me started from the
“Start Menu” screen on the control panel HMI. Pressing
“Unit Start” in the “Start Menu” screen will initiate a start
if all permissives to initiate a start are met. To initiate a
start, the following conditions must be met:
• Control Power is ON (Emergency Stop button is not
pressed and Master Control Relay is energized, indi-
cated by pilot light on front of panel)
• Blower Con fi guration is valid
• No Active General Trips (trips that apply to the whole
blower package)
NOTE
If an individual blower trips, in order to restart blower, it
must fi rst clear trip condition and be re-enabled locally
at the control panel.
When a start is initiated, the blower package will start if
all permissives to run are met. If all permissives to run
are not met, the control will wait in a “standby” mode
until all conditions to run are satis
fi ed. Any condition
that the control is waiting on is annunciated on the over-
view and menu screens and logged in the Event List. For
the blowers to start running, the following must be met:
• Control Power is ON (Emergency Stop button is not
pressed and Master Control Relay is energized, indi-
cated by pilot light on front of panel)
• No Active General Trips
• Blower Package start has been initiated by pressing
“Unit Start” in the “Start Menu” screen.
• Remote Permissive input is ON
• Soft run permissive from the DCS/Central Controller
is ON (if control by communications selected)
• Blower Anti-Recycle Timer is not active (speci fi c to
each blower – each blower has its own anti-recycle
function.)
• No Blower-Speci fi c Trips Active (speci fi c to each
blower)
ANTI-RECYCLE
After a blower motor stops, it is not allowed to re-start
again for a settable time. This is to protect the blower
motor. If the Anti-Recycle timer is active, a banner will
appear next to the speci
fi c blower on the main screen
that shows the remaining time. If a start is initiated,
the blower state indicator will indicate “Standby” until
the Anti-Recycle timer is done. If all other permissives
are met, the blower will re-start when its anti-recycle
timer expires. In multiple-blower applications, the anti-
recycle function is blower speci
fi c – one or more blowers
may be in anti-recycle without affecting the operation of
other blowers on the package.
AUTOMATIC SPEED CONTROL
For blowers that are con fi gured to run on PID speed con-
trol, a PID controller will adjust the speed of the blowers
to hold a pressure set point. Two control methods are
available:
• Discharge Pressure Control: Blower increases speed
to increase discharge Pressure to desired setpoint
• Suction Pressure Control: Blower increases speed to
lower suction pressure to desired setpoint
Any blowers con fi gured to run on PID speed control re-
ceive the same speed command from the PID control-
ler. Blowers con
fi gured to run on fi xed speed control will
maintain their fi xed speed set point. Variables that fac-
tor in to the automatic speed control are the following:
• Target pressure – the desired suction or discharge
pressure the blower package will try to maintain.