Standardizing The Lmv52 - Siemens LMV5 Series Technical Instructions

LMV Series
5. The VFD should be able to do a "flying start" so that the VFD will not try to stop a free‐wheeling
blower wheel before starting the wheel spinning again. Blower wheels frequently free‐wheel due to
draft and other factors.
6. Ramp times ‐ the VFD should be set to slightly faster ramp times compared to the LMV52 ramp
times (LMV52 parameters TimeNoFlame and OperatRampMod). If the shorter LMV52 ramp time is
set to 60 seconds, the ramp up and ramp down times in the VFD should be set no longer than 55
seconds. In general, a 5 second differential will work well in most situations.
Note: If short ramp times are necessary with large blowers (heavy blower wheels), a braking
resistor may be necessary. See the braking resistor explanation on the previous pages.
7. Ramps must be linear with the 4‐20mA signal. S‐shaped ramps and PID / filtering on the 4‐20mA
signal will cause speed faults on the LMV52.
8. The analog signal should be configured for a 4‐20mA signal and it should be spanned so that 4mA =
0Hz and 20mA = 62Hz (for blowers designed for 60 Hz power). The additional 2Hz is to make sure
that full blower speed is achievable even with a 19.5 mA standardization (see standardization
section below).
9. The motor nameplate data must be entered for the motor that the VFD is connected to.
10. Some VFDs have a feature that will stop ramping the drive if a critical limit in the drive is
approached. On some VFDs, this feature is referred to as "stall prevention". Two common limits are
the maximum amperage drawn and the DC bus voltage. Stall prevention, while protecting the drive,
can cause speed faults with the LMV52 due to the drive ceasing to ramp in concert with the LMV52.
If a braking resistor is used, stall prevention can typically be deactivated.
11. For Vector VFDs, perform at least a static auto‐tune so that the VFD "learns" the characteristics of
the motor it is connected to. A static auto‐tune does not require that the load (blower wheel) be
disconnected since the load is not spun. Some dynamic auto‐tunes require that the load is
disconnected.
12. If a braking resistor is being used, the braking resistor will typically have a high temperature switch.
The drive should be programmed and wired so that a braking resistor over temperature will cause
the drive to shut down.
Standardizing the LMV52
After the LMV52, VFD, blower, and speed sensor are installed and wired correctly (see Section 2), and
the VFD parameters are set correctly, the LMV52 must be standardized.
This only needs to be done once, as long as there are not changes to the VFD and / or blower. If any
changes are made (including VFD programming), it is recommended to re‐standardize so that the LMV52
can "learn" the change that was made.
SCC Inc. Page 9
HOME
Technical Instructions
Document No. LV5‐1000
Section 5