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Building Technologies Basic documentation LMV37.4... CC1P7546en
HVAC Products 11 Fan control 01.12.2009
11.11 Standardization of speed
Since the different types of fans operate at different speeds and signal handling should
be as straightforward as possible, all speeds in the system are standardized between 0
and 100%. For this reason, the VSD module uses a parameter which contains the
«standard speed» (100% speed). All absolute speeds refer to this speed.
If changes to the VSD or the fan are made, speed standardization should be repeated.
Caution!
• If automatic speed standardization is activated or if the standardized
speed is changed, the settings of air-fuel ratio control must be
checked! Any change of the standardized speed alters the assignment be-
tween the percentage values parameterized on the curves and the speed
• When the parameter set (refer to ACS J7352) is restored, the standardized
speed also reset. In that case, new standardization of the speed is required
To facilitate determination of the standardized speed, the LMV37.4... features automatic
speed standardization. The speed must be standardized while in standby mode. Speed
standardization is integrated in the setting process for electronic air-fuel ratio control, but
can also be started later from the parameter setting level. When using a release contact
for the VSD (external relay at fan output X3-05.1), the fan output is controlled during
speed standardization.
1. Start speed standardization
To start automatic speed standardization, set parameter 641 to
1.
Parameter
641 Control of VSD’ speed standardization
Error diagnostics of negative values (refer to error 82)
0 = no speed standardization
1 = speed standardization active
2. Drive the air damper to the prepurge position
Speed standardization begins when the air damper travels to the prepurge position.
When this position is reached, the air damper should be fully open so that the fan oper-
ates at full capacity.
3. Control the VSD
Control the VSD at 95% of maximum voltage.
A margin of 5% allows the speed to be readjusted should environmental conditions
change. This means that full speed (100%) is reached with 95% VSD control (refer to
section
Parameterizing the VSD).
4. Wait until the speed is higher and has stabilized
Before the 100% speed can be measured, the fan must have reached stationary condi-
tions. This means that the fan must operate under stable conditions above 650 rpm.
When this state is reached, a certain waiting time is observed, allowing the speed to fi-
nally stabilize.
5. Measure the speed and store it
When the speed has stabilized, measure and store it as the «standardized speed»
(100% speed).
Automatic speed stan-
dardization
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