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Siemens Building Technologies
Basic Documentation LMV5...
CC1P7550en
HVAC Products
18 Addendum 3: Variable speed drive (VSD) module
13.08.2004
18.1.3 Configuration of speed acquisition
The speed sensor to be used must be an inductive sensor (Namur or open collector
(pnp) (refer to subsection 15.1.1). The motor speed is acquired with an asymmetric sen-
sor disk having 3 protrusions spaced at 60°, 120° and 180° respectively. The number of
protrusions must be appropriately parameterized. The sensor disk is to be fitted such
that the pulse intervals are generated in the direction of rotation as described.
Parameter:
Num Puls per R
Since the different types of motors have different maximum speeds, the VSD module must
know the speed that corresponds to 100 %.
Since the standardized speed is difficult to adjust – but the correct adjustment has a
great impact on the control performance of the VSD module – an automatic measurement
function has been implemented.
Parameter:
Standard (deactivated / activated)
The speed should be standardized in standby mode.
When this function is activated, the air actuator will be driven to the prepurge position
first. The air actuator’s prepurge position should be adjusted such that the air damper is
fully open.
This action can be watched on the menu «Ratio Control»
→
«Settings»
→
«Gas / Oil»
→
«Curve Parameters»
Then, the VSD will be controlled at 95 %. A reserve of 5 % is left, enabling the VSD
module to safely reach the 100 % speed in situations where environmental conditions
may change. Once the motor speed has stabilized, that speed will then be standardized.
In other words, that speed will represent 100 %. That speed can be read using parameter
«StandardizedSp».
Parameter:
StandardizedSp
«StandardizedSp» should not be parameterized manually.
If, based on the steps described above, the burner’s rated output cannot be reached
(the fan is controlled at 47.5 Hz), proceed as follows:
−
Set the maximum frequency to 105.2 % of the motor’s nominal speed
This means that at a motor frequency of 50 Hz:
Parameterize the maximum frequency of the VSD to 50 Hz
•
1.052 = 52.6 Hz (on the
VSD)
−
Then, standardize
This standardization cannot lead to motor overloads since only 95 % of the maximum
control signal is delivered during standardization and the actual speed will be controlled
later in operation and monitored with «Safety time ratio control». Frequencies between
50 and 52.6 Hz are delivered only if this is necessary to reach the required speed due to
increased load.
If automatic speed standardization is activated, or if the standard-
ized speed is changed, the burner must be readjusted! Any change
to the standardized speed changes the assignment between the
parameterized percentages on the curves and the speed.
Standardization
Note
Note