Siemens LMV5 Series Technical Instructions page 143

LMV Series
If possible, shut off the burner switch. Let the burner get back to Phase 12 (standby).
1.
Access the cold start parameters through the following menu path:
2.
Params & Display > LoadController > ColdStart
Set parameter ThresholdOn to the minimum permissible temperature where the burner can be
released to modulate. Below this temperature, cold start will engage on initial startup (not
during normal operation). Set ThresholdOff to a temperature higher than ThresholdOn. If
already engaged, cold start will disengage at the ThresholdOff temperature. Setting
ThresholdOn and ThresholdOff is required for cold start.
NOTE: Parameters ThresholdOn and ThresholdOff are percentages based on the current
setpoint (W1). If an additional temperature sensor is used on a steam boiler, ThresholdOn
and ThresholdOff will be based on parameter Setp AddSensor.
For a steam boiler that is on a common header with other steam boilers, an additional
3.
temperature sensor is required for cold start. This will typically be a Pt1000 or Ni1000 RTD wired
to terminal X60. Pt100 is possible but not recommended. Choose the appropriate sensor via
parameter AdditionalSens.
There are four basic ways that the cold start can be set. These are:
4.
a. Basic Low Fire Hold
The LMV5 will be held at low fire until the ThresholdOff temperature is reached, and
then the LMV5 will be released to modulate. This "hold" will re‐engage when the
temperature falls below the ThresholdOn value. Parameter StageLoad must be set to 0.
b. Temperature‐based Stepping Start
The LMV5 will be held at low fire until a certain temperature change is detected, and
then a step up in burner output (load) will be taken. This continues until the
ThresholdOff temperature is reached. This will achieve the ThresholdOff temperature
faster than a basic low fire hold. Parameter StageLoad must be set to a value greater
than 0, since the step‐up in load is determined by this parameter. Parameter
StageSetp_Mod must also be set to determine the amount of temperature change that
will trigger a step‐up in load. Parameter MaxTmeMod should be set to a high number
(30 min) so that it has no effect.
c. Time‐based Stepping Start
The LMV5 will be held at low fire until a certain time elapses, and then a step‐up in load
will be taken. This continues until the ThresholdOff value is reached. StageLoad must
be set to a value greater than 0, since the step‐up in load is determined by this
parameter. Parameter StageSetp_Mod should be set to a high number (80%) so that it
has no effect. Parameter MaxTmeMod is set to determine how much time should
elapse before the next load step is triggered.
SCC Inc. Page 25
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Technical Instructions
Document No. LV5‐1000
Section 4