Siemens LMV5 Quick Start Manual page 180

Set the O2 Ratio Control and the O2 Control Curves
3) These are both found under:
Parameters & Display > O2 Contr/Guard > Gas/Oil Settings > O2 Control.
First, the O2 Ratio Control needs to be set for point 2. Under parameter O2 control,
Point 2 should appear, since it is not possible to trim on Point 1.
4) Press the enter key while Point 2 is displayed, and the LMV52 will drive the
actuators / VSD to Point 2 on the Fuel-Air Ratio Curve. The AZL5 will then prompt
the operator to press enter again when the displayed % O2 value has stabilized.
Note: This stabilization will be slower at low fire (average of 15-30 seconds after the
actuators / VSD have driven to the point) and faster at high fire.
If the enter key is pressed prematurely, the recorded %O2 will NOT accurately
represent the %O2 for the point on the O2 ratio control point. If this happens, delay
time will NOT be measured accurately in a later step and this will cause faults during
operation.
5) Once the enter key is pressed, the % O2 shown on the AZL5 is locked in
to be the % O2 for the O2 ratio control point (actuators / VSD are at their Fuel-Air
Ratio Control positions). The % O2 for the O2 Ratio Control is now set for Point 2.
6) Next, the O2 Control needs to be set for point 2. This is done by increasing the
Standard Val value, which drives the air influenced actuators back down their curves
(closed), and should decrease the %O2 read on the AZL5. Once the desired %O2 is
achieved, Point 2 can be saved by pressing the enter key to the left of the Standard
Val, pressing escape once, and then pressing the enter key to finally store the point.
Note: The O2 control point must be at least 1% O2 below the %O2 value entered for the
ratio control curve, and at least 0.5% O2 above %O2 entered for the O2 Monitor
curve. Thus, the lean to rich band must be at least 1.5 %O2. In practice, the O2
system is easier to commission and operate on most burners if the %O2 between the
O2 Control and the O2 Monitor is 1.0% O2 or more.
The % O2 for the O2 Control is now set for Point 2.
7) Once enter is pressed to save the point, delay time is automatically measured.
Delay time is typically measured on point 2 or whatever the value is for
LowfireAdaptPtNo is and at high fire (the highest point number). This is done so
that the LMV52 can "learn" the response time of the boiler / burner at low and high
fire. To achieve this, the LMV52 drives the actuators from their position at the O2
control curve point back to their position at the ratio control point. The LMV52 then
measures how long it takes for the %O2 in the stack to climb back up to the
approximate %O2 that was locked in for the ratio control curve.
If the measured %O2 value in the stack approaches the %O2 that was locked in on
for the O2 ratio control curve in less than 28 seconds, a successful delay time
measurement should result. If the delay time measurement is unsuccessful, the
probable cause is an unrepresentative %O2 value for the O2 Ratio control curve, or
parameter OptgMode is not set to Man Deact. Also see the above note pertaining to
delay time.
8) Repeat the process outlined above for every point that was defined in the Fuel-Air
Ratio curve. Delay time will also be measured a second time at high fire, which is
typically highest numbered point.
9) After this is completed, the O2 trim can put into operation. This is done under
parameter OptgMode. Typically, this is set to Con Auto Deact, but other settings
are possible. Section 4-2 explains the different choices for this parameter.
Note: If necessary, see section 5 for additional troubleshooting information.
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