Siemens LMV3 series Technical Instructions page 119

LMV Series Technical Instructions
Document No. LV3-1000
If the speed control signal is increased to the maximum allowable signal and the blower RPM is still low,
an Error Code 83, Diagnostic Code 2 will be displayed on the AZL.
If the speed control signal is decreased to the minimum allowable signal and the blower RPM is still high,
an Error Code 83, Diagnostic Code 1 will be displayed on the AZL.
The reason that the standardization is done at 9.5 VDC instead of at 10 VDC is to give the LMV3 some
additional "room" to increase the speed control signal for a low RPM condition at high fire. Because the
standardization is done at 9.5 VDC, the analog input on the VFD is spanned so that 10 VDC = 62 Hz. This
is done so that the blower will still achieve full 60 Hz blower speed at high fire on jobs where the blower
is just large enough.
NOTE: Most VFDs can be scaled to output 400 Hz or more. Consult the blower and / or motor
manufacturer before over-speeding the motor and blower, since blower wheels and motor rotors can
catastrophically fail if RPM limits are exceeded.
In addition to limits on how much the speed control signal can be compensated, the LMV3 also has
limits on how far the blower speed can deviate from the standardized speed baseline. These blower
speed deviation limits are valid, independent of the activation or deactivation of the LMV3's internal
speed control (parameter 661). The next section explains how the blower speed is monitored when the
burner is in operation.
SCC Inc. Page 15 Section 5