Siemens LMV5 Quick Start Manual page 135

Measurement of Delay time Unsuccessful
When setting low fire point, or the high fire point, on the O2 control curve, messages are
received that say words to the effect of: Measurement of Delay time Unsuccessful.
Check the following:
1) Verify that OptgMode is set to man deact.
Verify that LowfireAdaptPt is set to 2 (combustion curve point 2) or higher if desired.
The high fire point cannot be changed from the highest point in your combustion curve.
2) This typically occurs at low fire when the velocity of the combustion gasses through the
boiler is relatively slow. The Delay time is defined as the length of time it takes a change in
the air damper position to be detected by the O2 sensor. This time is longer at low fire and
shorter at high fire due to gas velocity.
When the points on the O2 control curve are set, the LMV5 will prompt at every point with
press enter after the O2 value has stabilized. Pressing enter then sets the %O2 for the
O2 ratio control curve.
This problem is typically cured by waiting at least 30 seconds after the LMV5
asks press enter after the O2 value has stabilized, since the problem is typically caused
by a non-representative %O2 value for the O2 ratio control curve.
Please see Section 6 for additional information.
O2 trim automatically deactivated
The LMV5 gives warnings that the O2 trim has been automatically deactivated.
There are many different problems that can cause an auto deactivation of the O2 trim system.
The most common are:
1) Go into the fault history. If the LMV5 faulted on error code B5 diagnostic code 01,
this states that the sensed % O2 value has gone below the O2 Monitor curve
for more than 3 seconds and the trim deactivated.
The most common solutions to this problem are increasing the % O2 gap between the O2
control curve and the O2 monitor curve at and around the point (can be determined by the
load-stamp on the fault) where the fault occurred.
Also, Parameters O2 Offset Gas or O2 offset Oil can be increased in 0.5% increments.
Parameter LoadCtrlSuspend can also be decreased in 1% increments.
See Section 4-2 for more information on these parameters
2) If the LMV5 faulted on error code AB diagnostic code 15 or 16,
check the configuration of the ambient (supply air) sensor and the stack (flue) gas sensor.
If these sensors are activated and are not wired in or are not functioning correctly,
the O2 trim will automatically deactivate immediately after it is reactivated.
3) If the LMV5 faulted on error code AB, diagnostic code 20,
check the temperature of the QGO20 sensor.
This can be found under:
Params & Display > O2 Module > Displayed Values > QGO SensorTemp.
The temperature should be at least 1202
If the temperature falls below this value during prepurge or anytime during operation, the
QGO20 sensor may be mounted improperly, or gas velocity may be too high or too low.
See Section 2 for proper QGO20 mounting
LMV5 QSG Rev 4
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F.
Sec 5 Pg 9 www.scccombustion.com