Operation - Siemens LMV5 Series Technical Instructions

Technical Instructions
Document No. LV5-8000
Direct Start (continued)

Operation

Direct start accelerates the startup sequence in the following instances:
• The LMV5 loses the call for heat (terminal X5-03.1), and regains it before or during
postpurge (phase 62-78)
• The LMV5 receives a fuel changeover request (terminal X4-01.1 or X4-01.2) during
burner operation (phase 60) or shutdown (phases 62-78)
If either of these situations occurs, the LMV5:
1. Drives to low fire (phase 62) and shuts the fuel valves.
2. Ensures the flame signal drops out during the afterburn time (phase 70).
3. Drives to postpurge position (phase 72) and performs its mandatory postpurge
(PostpurgeT1Gas(Oil), phase 74).
4. Proceeds to phase 79 and either powers on or off the 3-way solenoid valve dependent
upon the setting of parameter "Start/PS-Valve". The LMV5 verifies the operation of the
blower air switch via input terminal X3-02.1 during phase 79.
5. Drives directly to prepurge position (phase 24) and proceeds to startup as normal.
Appendix A Page 6
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