Multistage Control; General; Load-Dependent Activation Of The Higher Burner Stages - Siemens LMV5 Series Basic Documentation

General

Load-dependent activation
of the higher burner stages
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6.4.3 Multistage control

When selecting «Oil» as a fuel, the LMV5... must be set to «2-stage» or «3-stage»,
depending on the type of burner used, using parameter «Operation Mode» (refer to
section 5.4 → «Operating mode»).
In these 2 operating modes, the PID algorithm is not required and will not be calculated.
The 2 or 3 fuel stages are activated and deactivated depending on the actual values,
the parameterized switching differentials_Stage1...3 (refer to subsection 5. 4. 1) and
the parameterized reaction thresholds Q2 and Q3.
This approach is used to reduce the switching frequency of the higher stages.
The integral of the control deviation over time is generated
−
Switching on of stage 2 will be locked until the temperature has dropped below the
−
adjustable reaction threshold Q2
Switching on of stage 3 will be locked until the temperature has dropped below the
−
adjustable reaction threshold Q3
Parameter:
ThreshStage2On (Q2), ThreshStage3On (Q3)
Reaction thresholds Q2 and Q3 (integral of control deviation (K) x time
(s))
If the temperature often drops below the switching on thresholds, the integrals will be
added up and the higher stage switched on when the associated Q-value is reached.
If, before that, the setpoint is reached with the lower stage, the counter will be reset.
Basic Documentation LMV51...
6 Temperature or pressure controller (internal load controller LC)
CC1P7550en
01.10.2003