Danfoss VLT FC 102 Operating Instructions Manual page 82

6 How to Programme the Low Harmonic Drive
Group Title
13- Smart Logic Controller
14- Special Functions
6
15- FC Information
16- Data Readouts
18- Info & Readouts
20- FC Closed Loop
21- Extended Closed Loop
22- Application Functions
82
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 economiser mode
in a simple AHU cooling application control scheme where there is no BMS. For such an application the
SLC can monitor the outside air relative humidity and if it is below a defined value, the supply air tem-
perature setpoint could be automatically increased. With the frequency converter monitoring the outside
air relative humidity and supply air temperature via it's 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 frequency converter including: setting of the
switching frequency to reduce audible noise from the motor (sometimes required for fan applications);
kinetic back-up function (especially useful for critical applications in semi-conductor installations where
performance under mains dip/mains loss is important); mains imbalance protection; automatic reset (to
avoid the need for a manual reset of Alarms); energy optimisation parameters (which typically do not
need changing but enable fine tuning of this automatic function (if necessary) ensuring the frequency
converter and motor combination operate at their optimum efficiency at full and partial load conditions)
and auto-derating functions (which enable the frequency converter 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 prevantative 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 3 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 philosophy
for multi-zone applications; programming of the setpoint(s) and manual or auto-tuning of the PI(D) loop.
Parameters used to configure the 3 extended closed loop PI(D) controllers which for example can be
used to control external actuators (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 the each of the PI(D) controllers.
Parameters used to monitor, protect and control pumps, fans and compressors including: no flow de-
tection and protection of pumps (including auto-setup of this function); dry pump protection; end of
curve detection and protection of pumps; sleep mode (especially useful for cooling tower and booster
pump sets); broken belt detection (typically used for fan applications to detect no air flow instead of
using a ∆p switch installed across the fan); short cycle protection of compressors and pump flow com-
pensation of setpoint (especially useful for secondary chilled water pump applications where the ∆p
sensor has been installed close to the pump and not acoss the furthest most significant load(s) in the
system; using this function can compensate for the sensor installation and help to realise the maximum
energy savings).
®
MG.16.A1.02 - VLT is a registered Danfoss trademark
VLT HVAC Low Harmonic Drive Operating In-
structions