Technical Instructions LMV Series
Document No. LV5-800
0
Appendix A Page 40 SCC Inc.
VFD Bypass (continued)
Single Fuel Operation
1. When the “VFD Bypass
Switch” is in VFD mode, motor contactors K1 and K2 are
energized. Power flows through the VFD to the motor. Bypass contactor K3 remains
de-energized. The fuel select terminal (X31-01.1) on the AGM60 is de-energized, so the
LMV52 runs gas. All inputs and outputs are connected through the AGM60 to the
LMV52 gas terminals.
2. When the “VFD Bypass Switch” is in Fan mode, motor contactors K1 and K2 are de-
energized and no power flows to the VFD. Power runs directly to the motor through
bypass contactor K3 once the fan output (X3-01.1) is energized in phase 22. The fuel
select terminal (X31-01.1) on the AGM60 is energized, so the LMV52 runs oil. All inputs
and outputs are connected through the AGM60 to the LMV52 oil terminals.
3. If the “VFD Bypass Switch” is switched during operation, the LMV52 immediately loses
its call for heat and goes through its shutdown sequence. When the fan output (X3-
01.1) de-energizes after phase 78, terminal X32-01.5 on the AGM60 becomes de-
energized, causing the switchover of all inputs and outputs connected through the
AGM60 and the motor contactors.
Note: Even though this is a single fuel system running gas, the LMV52 display will state
it is running oil when the “VFD Bypass Switch” is in Fan mode.
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