Azl Says "Fan Speed Not Reached" Or "Control Range Limitation Vsd Module - Siemens LMV5 Series Technical Instructions

Technical Instructions
Document No. LV5‐1000
AZL Says "Fan Speed Not Reached" or "Control Range Limitation VSD Module"
During burner operation, the LMV52 sends a 0/4‐20 mA signal to the VSD to control the speed
of the blower. The speed sensor sends feedback to the LMV52 to let it know the actual speed
of the blower. If the speed is too high or too low, the LMV52 will increase or decrease the
signal to the VSD accordingly. However, there are limits on how much the LMV52 can increase
or decrease the signal. If these limits are met, the LMV52 will lockout with one of the following
messages:
 "Fan Speed Not Reached" – Error code 15, diagnostic 10 or 40
 "Control Range Limitation VSD Module" – Error code A9, diagnostic 0D
"Fan Speed Not Reached" indicates that the blower speed is still too low even though the
LMV52 has increased the 0/4‐20mA signal as far as possible.
"Control Range Limitation VSD Module" indicates that the blower speed is too high even though
the LMV52 has decreased the 0/4‐20mA signal as far as possible.
If either of these messages appears, do the following:
1. Increase the ramp times of both the VSD and LMV52. Shorter ramp times on the VSD and
LMV52 create a more demanding application for the VSD. Simply put, a shorter ramp time
will cause the VSD to draw or absorb much more amperage for a given change in blower
speed since the change in speed occurs more quickly. To adjust the ramp times of the
LMV52, use the following menu paths:
Params & Display > RatioControl > Times > OperatRampMod
Params & Display > RatioControl > Times > TimeNoFlame
2. Large blower motors connected to large, heavy blower wheels have high rotating inertia.
As the inertia of the blower wheel increases, the power needed to accelerate and
decelerate the blower increases. If increasing the ramp times does not help, a braking
resistor may need to be installed on the VSD to help decrease the speed of the blower
motor more quickly.
Section 7 Page 22
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