Controls, Start-Up, Operation, Service and ... - Climayoreo

After the exhaust fan relay turns on, PID control ensues without
an “I” term:
Error = BP – BP.SP
K = 1000 * BP.TM / 60 (normalize the PID control for run rate)
P = K * BP.P * (error)
D = K * BP.D * (error - error computed last time through the
PID)
VFD control signal (clamped between 0 and 100%) = VFD
Output last time through + (P + D)
NOTE: The sum of P + D will be clamped on any timed calculation
to an internally calculated value which guarantees the
VFD is not commanded more or less an amount, than it cannot
achieve before the next time VFD capacity is again calculated.
Bringing the single speed fan (P.E.2) ON and OFF is coordinated
with the VFD speed. When building pressure first
becomes active, P.E.2 is OFF, P.E.1 is ON and the VFD is
allowed to climb to 100%. BP.CL will be used to act as hysteresis
so that when the P + D term is evaluated and it exceeds
BP.CL, the control will go through a one-minute period hold
off time where the VFD is commanded to BP.CL, and P.E.2 is
brought on. After the transition to P.E.2 ON is complete, the
control will continue to control the VFD from BP.CL%. If BP
rises, the control will speed up the VFD. Should the VFD drop
to 0%, and the next time through the PID the P + D term calculation
is less than – BP.CL, the control will go through another
one-minute PID hold off period where P.E.2 is commanded
OFF and the VFD is commanded to 100 – BP.CL.
ConfigurationBPBP.CF =5 (Return/Exhaust Control)
— Fan tracking is the method of control used on plenum return
fan option. The fan tracking algorithm controls the exhaust/
return fan VFD and the exhaust fan relay. The ComfortLink
controls use a flow station to measure the flow of both the supply
and the return fans. The speed of the return fan is controlled
by maintaining a delta cfm (usually with supply airflow being
greater of the two) between the two fans. The building pressure
is controlled by maintaining this delta cfm between the two
fans. In general, the greater the delta between supply airflow
and return airflow, the higher the building pressure will be.
Conversely, as the return airflow quantity increases above
the supply airflow, the lower the building pressure will be.
Whenever there is a request for the supply fan (or there is the
presence of the IGC feedback on gas heat units), the return fan
is started. The delta cfm is defined as S.CFM – R.CFM. The
return fan VFD is controlled by a PID on the error of delta cfm
actual from delta cfm set point. If the error is positive the drive
will increase speed. If the error is negative the drive will
decrease speed.
NOTE: These configurations are used only if Fan Tracking
Learning is enabled. When Fan Tracking Learning is enabled,
the control will adjust the delta cfm (FT.ST) between the
supply and return fan if the building pressure deviates from the
Building Pressure Set Point (BP.SP). Periodically, at the rate
set by the fan track learn rate (FT.TM), the delta cfm is
adjusted upward or downward with a maximum adjustment
at a given instance to be no greater than fan track max
correction (FT.AD). The delta cfm can not ever be adjusted
greater than or less than the fan track initial delta cfm (FT.ST)
than by the Fan Track Max Clamp (FT.MX).
CONFIGURING THE BUILDING PRESSURE ACTUA-
TORS (BP.CF = 2) TO COMMUNICATE VIA ACTUATOR
SERIAL NUMBER — Every actuator used in the P Series
control system has its own unique serial number. The rooftop
control uses this serial number to communicate with the
actuator. These serial numbers are programmed at the factory
and should not need changing. Should field replacement of an
actuator become necessary, it will be necessary to configure the
serial numbers of the new actuator. Four individual numbers
make up each serial number and these can be programmed to
match the serial number of the actuators in the building
74
pressure actuator configurations group, ACT.C.BP.1 and
BP.2 (SN.1, SN.2, SN.3, SN.4).
NOTE: The serial numbers can be found inside the control
doors of the unit as well as on the actuator itself. If an actuator
is replaced in the field, it is a good idea to remove the additional
peel-off serial number sticker on the actuator and cover
up the old one inside the control doors.
CONTROL ANGLE ALARM CONFIGURATION C.ALM
(BP.CF = 2) — The building pressure actuators learn what its
end stops are though a calibration at the factory. Field-installed
actuators may be calibrated in the Service Test mode. When an
actuator learns its end stops through calibration, it stores the
control angle. The actuator will resolve this control angle and
express its operation in a percent (%) of this learned range.
If a building pressure actuator has not learned a sufficient
control angle during calibration, the actuator will be unable to
control building pressure. For this reason the building pressure
actuators used in the P Series control system have configurable
control angle alarm low limits in the Building Pressure Actuator
Configurations group, ACT.CBP.1 and BP.2. (C.A.LM).
If the control angle learned through calibration is less than
C.A.LM, an alert will occur and the actuator will not function.
NOTE: This configuration does not typically need adjustment.
It is configurable for the small number of jobs which may
require a custom solution or workaround.
Smoke Control Modes — There are four smoke control
modes that can be used to control smoke within areas serviced
by the unit: Pressurization mode, Evacuation mode,
Smoke Purge mode, and Fire Shutdown. Evacuation, Pressurization
and Smoke Purge modes require the controls expansion
board (CEM). The Fire Shutdown input is located on the main
board (MBB) on terminals TB201-1 and 2. The unit may also
be equipped with a factory-installed return air smoke detector
that is wired to TB201-1,2 and will shut the unit down if a
smoke condition is determined. Field-monitoring wiring can be
connected to terminal TB201-1 and 2 to monitor the smoke detector.
Inputs on the CEM board can be used to put the unit in
the Pressurization, Evacuation, and Smoke Purge modes.
These switches or inputs are connected to TB202 as shown below.
Refer to Major System Components section on page 115
for wiring diagrams.
Pressurization — TB202-18 and 19
Evacuation — TB202-16 and 17
Smoke Purge — TB202-14 and 15
Each mode must be energized individually on discrete inputs
and the corresponding alarm is initiated when a mode is
activated. The fire system provides a normally closed dry
contact closure. Multiple smoke control inputs, sensed by the
control will force the unit into a Fire Shutdown mode.
FIRE SMOKE INPUTS — These discrete inputs can be
found on the local display under InputsFIRE.
CCN
ITEM EXPANSION RANGE
POINT WRITE
STATUS
FIRE FIRE-SMOKE INPUTS
FSD Fire Shutdown Input ALRM/NORM FSD forcible
PRES Pressurization Input ALRM/NORM PRES forcible
EVAC Evacuation Input ALRM/NORM EVAC forcible
PURG Smoke Purge Input ALRM/NORM PURG forcible
Fire Shutdown Mode — This mode will cause an immediate
and complete shutdown of the unit.
Pressurization Mode — This mode attempts to raise the pressure
of a space to prevent smoke infiltration from an adjacent
space. Opening the economizer (thereby closing the return air
damper), shutting down power exhaust and turning the indoor
fan on will increase pressure in the space.
Evacuation Mode — This mode attempts to lower the pressure
of the space to prevent infiltrating an adjacent space with