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Building Technologies Basic documentation LMV37.4... CC1P7546en
12 Fan control 17.12.2018
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 fuel-air 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 pin 1), the fan output is controlled during
speed standardization.
1. Start speed standardization
To start automatic speed standardization, set parameter 641 to 1.
No. Parameter
641 Control of VSD’s 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
operates at full capacity.
3. Control the VSD
The VSD is activated with 95% of the maximum voltage during active speed control.
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
chapter Setting the parameters of the VSD).
The specification for determining the standardized speed varies depending on the speed
control setting and the selected operating mode. This means that a slightly reduced fan
speed may be available.
Internal
control
parameter
661
Electronic fuel-air ratio
control (e.g. operating
mode 1: G mod)
Pneumatic fuel-air ratio control (e.g.
operating mode 7: G mod pneu)
1 95% regulated operation 100% pneumatic
0 98% unregulated operation 98% pneumatic (deactivated control
has higher priority than pneumatic fuel-
air ratio control)
No. Parameter
661
LMV37.4 internal speed control
0 = deactivated (self-regulated PWM fan)
1 = activated (VSD)
4. Wait until the speed is higher and has stabilized
Before the 100% speed can be measured, the fan must have reached stationary
conditions. 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 eventually 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
standardization
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