PCC-IV Instruction Manual (Rev. 0.1)
Page 6-16
Section 6
– Blockware Functions
Technical Reference
Automated Storing of (X, Y) Data in Learn Mode:
If the Learn Enable Input = 1, and Clear Input = 0, Then: During the first scan that the Learn Input changes from 0
to 1; the current X and Y Inputs are stored in a (X
i
, Yi) parameter pair. The rules for selecting the (X
i
, Yi) parameter
pair are as follows:
If less than 11 “active X” Parameters exist (i.e., X
i
>
–150.00%):
Is the current “X” Input /- 2.00% of an existing “X” Parameter?
Yes: Replace the existing (X, Y
) parameter values with the “X” and “Y” Inputs.
This allo
ws you to “Edit” an existing “Y” value using Learn Mode.
No: Store the current “X” and “Y” Inputs in a new (X
i
, Yi) parameter pair such
that the “X” values remain in ascending order (i.e. X1 < X2 < X3 < X4 …).
F(X)
automatically moves all (X, Y) parameter pairs above X
i
up one
position.
If 11
active “X” Parameters exist:
Replace the existing breakpoint (X, Y) parameter pair that is closest to the
current “X” value with the current “X” and “Y” Inputs.
The above process only occurs during the first scan that the Learn Input changes from 0 to
1. If Learn = 1 for more than one scan, the subsequent scans do not “Learn” any additional
values.
"Clearing" (X, Y) Data
If the Learn Enable Input = 1, and Clear Input = 1, Then: During the first scan that the Learn Input changes from 0
to 1; all eleven “Y” parameters are set equal to Parameter 24, the “Y VALUES AFTER CLEAR” parameter. All eleven
“X” Parameters are set equal to -150.00% (i.e., inactive). This allows the Block Output to be set to a defined value
until a new curve is entered.
Blockware Example: The Blockware on the next page shows a simplified parallel positioning combustion control
application that uses two
F(x)
Blocks. The
F(x)
in
Block 55 holds the fuel-to-air characterizing curves for one fuel.
The
F(x)
in
Block 62 holds the Oxygen Setpoint versus Load (I.e. Firing Rate) characterizing curves for one fuel.
A second or third fuel could be accommodated by adding additional
F(x)
Blocks and
ASW
Blocks to select the
correct
F(x)
Block based on the fuel currently being fired.
WARNING:
This simplified example does not show all the required safety features that would be
included in a real combustion control strategy. Do not use the Blockware example shown
for an actual application.
The Blockware is configured to use Learn Mode for simultaneous entry of the fuel/air and Oxygen Setpoint/Load
F(x)
curves. The general procedure a Burner Technician would follow is:
1.) Enable Learn Mode
2.) Put BOTH the Fuel and Air Actuators in Manual
Manually position the Fuel and Air at Minimum Firing Rate for best combustion
Allow the Oxygen Analyzer signal to stabilize
Press the front panel pushbutton that is configured as the "STORE" button.
Block 55 will add an (X, Y) breakpoint for the current fuel (X) and air (Y) positions.
Block 62 will add an (X, Y) breakpoint for the current fuel (X) and Oxygen (Y) Levels.
3.) Repeat the above 4 steps at 10 additional firing rates (less if applicable). Make sure
that the Maximum firing rate is "Stored".
4.) Disable Learn Mode
