Danfoss VLT HVACDrive Instruction Manual page 129

VLT ® HVAC Drive Instruction Manual
Group Title
13- Smart Logic Controller
14- Special Functions
15- FC Information
16- Data Readouts
18- Info & Readouts
20- FC Closed-loop
21- Extended Closed-loop
Function
Parameters used to configure the built in Smart Logic Controller (SLC), which can be used for simple
functions such as comparators (e.g., if running above xHz, activate output relay), timers (e.g., when a
start signal is applied, first activate output relay to open supply air damper and wait x seconds before
ramping up) or a more complex sequence of user defined actions executed by the SLC when the asso-
ciated user defined event is evaluated as TRUE by the SLC. (For example, initiate an economizer mode
in a simple AHU cooling application control scheme where there is no BMS. For such an application, the
SLC can monitor the relative humidity of the outside air, and if it is below a defined value, the supply air
temperature setpoint could be automatically increased. With the adjustable frequency drive monitoring
the relative humidity of the outside air and supply air temperature via its analog inputs and controlling
the chilled water valve via one of the extended PI(D) loops and an analog output, it would then modulate
that valve to maintain a higher supply air temperature). The SLC can often replace the need for other
external control equipment.
Parameters used to configure special functions of the adjustable frequency drive including: setting of
the switching frequency to reduce audible noise from the motor (sometimes required for fan applica-
tions); kinetic backup function (especially useful for critical applications in semi-conductor installations
where performance under line power dip/line power loss is important); line imbalance protection; au-
tomatic reset (to avoid the need for a manual reset of alarms); energy optimization parameters (which
typically do not need changing but enable fine tuning of this automatic function (if necessary) ensuring
the adjustable frequency drive and motor combination operate at their optimum efficiency at full and
partial load conditions) and auto-derating functions (which enable the adjustable frequency drive to
continue operation at reduced performance under extreme operating conditions ensuring maximum up
time).
Parameters providing operating data and other drive information including: operating and running hour
counters; kWh counter; resetting of the running and kWh counters; alarm/fault log (where the past 10
alarms are logged along with any associated value and time) and drive and option card indentification
parameters such as code number and software version.
Read only parameters which display the status/value of many operating variables which can be displayed
on the LCP or viewed in this parameter group. These parameters can be particularly useful during com-
missioning when interfacing with a BMS via a high level interface.
Read-only parameters which display the last 10 preventative maintenance log items, actions and time
and the value of analog inputs and outputs on the analog I/O option card which can be particularly useful
during commissioning when interfacing with a BMS via a high level interface.
Parameters used to configure the closed-loop PI(D) controller which controls the speed of the pump,
fan or compressor in closed-loop mode including: defining where each of the three possible feedback
signals come from (e.g., which analog input or the BMS HLI); conversion factor for each of the feedback
signals (e.g., where a pressure signal is used for indication of flow in an AHU or converting from pressure
to temperature in a compressor application); engineering unit for the reference and feedback (e.g., Pa,
kPa, m Wg, in Wg, bar, m3/s, m3/h, °C, °F, etc.); the function (e.g., sum, difference, average, minimum
or maximum) used to calculate the resulting feedback for single zone applications or the control philos-
ophy for multi-zone applications; programming of the setpoint(s) and manual or auto-tuning of the PI(D)
loop.
Parameters used to configure the three extended closed-loop PI(D) controllers which, for example, can
be used to control external servos (e.g., chilled water valve to maintain supply air temperature in a VAV
system) including: engineering unit for the reference and feedback of each controller (e.g., °C, °F, etc.);
defining the range of the reference/setpoint for each controller; defining where each of the references/
setpoints and feedback signals come from (e.g., which analog input or the BMS HLI); programming of
the setpoint and manual or auto-tuning of each of the PI(D) controllers.
MG.11.AB.22 - VLT ® is a registered Danfoss trademark
7 How to Program the Adjustable Frequency
Drive
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