Pre-Requisites For Lmv52 Systems With A Vfd - Siemens LMV5 Series Technical Instructions

Technical Instructions
Document No. LV5‐1000
7. A method of determining firing rate (fuel flow within +/‐ 5%) should be used. This, in
combination with knowledge of high fire and turndown, is used to set the load numbers on each
curve point. An Excel spreadsheet is available for this purpose.
8. For steam boilers, the feedwater supply must be adequate to support high fire operation.
Feedwater controls must be working properly.
9. The load on the boiler must be adequate so that a burner / boiler combination can be run at
high fire for a minimum of 5 minutes.
Pre‐Requisites for LMV52 Systems with a VFD
1. All pre‐requisites of the Basic LMV51 system apply.
2. Blower motor speed sensor and speed wheel must be installed correctly. See Appendix B (LMV5
Accessories Guide) for more details.
3. Vector‐type VFDs are highly recommended due to their inherently more precise motor speed
control. Volt / Hz VFDs are not recommended due to less precise speed control.
4. Proper grounding between the LMV5, the VFD, and the motor must be installed. See Section 2
(Wiring) for more details.
5. VFD parameters must be set correctly to be compatible with both the LMV52 and the blower
motor. See Section 5 (VSD) for more details. Particular attention should be paid to the
following:
a. Analog signal configuration. Both the LMV52 and VFD must be configured for a 4‐20mA
signal.
b. Ramp rates between the LMV52 and the VFD must be compatible. In general, ramp
rates of the VFD should be 10 seconds less than the LMV52.
c. VFD must be set up as a slave unit for a 4‐20mA signal. Damping, dead band, and PID
functions must be disabled.
d. The frequency (Hz) output of the drive must be directly proportional to the analog input
signal.
e. Acceleration / deceleration curves must be linear instead of "S‐shaped".
f. Ramp settings must be ramp up / ramp down instead of ramp up / coast down.
g. Any type of damping or stall prevention in the VFD should be deactivated.
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