Honeywell 800 Series Manual page 15

Below are example steps for testing and resolution of hot
refractory hold in.
1. Operate the burner until the refractory reaches its
maximum temperature. If the installation is a multi-
fuel burner, burn the heavier fuel that is most likely
to reflect, bend or obscure the hot refractory steady
infrared radiation.
2. When the maximum refractory temperature is
reached, close all manual shutoff valves, or open the
electrical circuits of all automatic fuel valves.
3. Visually observe the monitored flame, and note how
long it takes from the time of flame loss, to when the
scanner flamecounts fall below the off threshold,
turning off the flame relay. If this time is longer than
the FFRT time, then the scanner is sensing hot
refractory.
4. Immediately terminate the firing cycle. Lower the
setpoint to the operating controller, or set the Fuel
Selector Switch to OFF. Do not open the master
switch. NOTE: Some burners continue to purge oil
lines between the valves and nozzles even though
the fuel valves are closed. Terminating the firing
cycle (instead of opening the master switch) allows
purging the combustion chamber. This reduces a
buildup of fuel vapors in the combustion chamber
caused by oil line purging.
5. If the burner scanner is detecting hot refractory, use
one or more of the following suggestions to reduce
IR level, and repeat test steps to ensure scanner is no
longer sensing hot refractory:
• Reduce IR gain setting.
• Add an orifice to the flame scanner (see
accessories).
• Re-sight the scanner at a cooler, more distant
part of the combustion chamber. Make sure the
detector properly sights the monitored flame.
• Try lengthening the sight pipe or decreasing the
pipe diameter size.
XRAY Radiation
Xray radiation does not affect signal processor, or viewing
head IR sensor performance, and does not adversely
affect viewing head tube sensor performance under the
following conditions:
Radiation Source of 65 Curie Iridium 192
Distance > 5'
Exposure type Direct
UV tube gain set to default
Flame off threshold >600
If viewing heads are subjected to more severe conditions,
system must be tested to ensure that radiation does not
cause flame-counts above flame off threshold. If this
occurs, flame off threshold must be increased, UV tube
gain must be reduced, or lead shielding must be used.
Ratio (%) Relay Off/Relay On Setpoint
For a flowchart of this setpoint process, refer to Fig. 24.
The key labeled RATIO (%) RELAY OFF/RELAY ON is used
to set the RELAY OFF SET POINT at a percentage of the
RELAY ON SET POINT. This percentage is adjustable from
20% to 80%. For example, if the RELAY ON SET POINT is
set to 16 and the RATIO (%) is set to 50% (the factory
default values) the relay will energize if the displayed
count goes to 16 or higher and de-energize when the
count drops to 08 or less for one to three seconds,
HONEYWELL MODEL 700/800 SIGNAL PROCESSOR AND VIEWING HEAD
depending on the FFRT (Flame Failure Response Time)
setting. The adjustment of the RATIO setting is live.
Adjustments will cause the Flame Relay to de-energize
immediately, ignoring FFRT settings.
To access this setpoint, press and hold the ACCEPT
RATIO/SET GAIN button for 2 seconds until the current
value is displayed. While the value is displayed,
adjustments may be made via the INCREASE or
DECREASE arrow buttons. To store the new setting, press
the STORE button until "- -" is shown, indicating the value
has been accepted.
If no activity occurs for a period of four seconds while the
value is displayed, the RATIO display will disappear and
the old ratio setpoint will take effect.
To exit the menu at any time without saving changes,
simply press the RESET/rE button.
Setting FFRT (Flame Failure Response
Time)
To access the FFRT setpoint, press and hold the FFRT
1/2/3 SEC OPTION button for 2 seconds until the current
value is displayed. Refer to Fig. 25 for the setup flowchart.
The FFRT can be set at 1, 2 or 3 seconds. While the value is
displayed, adjustments may be made via the INCREASE or
DECREASE arrow buttons. To store the new setting, press
the STORE button until "- -" is shown, indicating the value
has been accepted.
The FFRT changes are not live; they take effect only if the
STORE button is pressed. FFRT values do not relate to the
RELAY ON SETPOINT and RATIO (%)/RELAY OFF values.
Therefore, during automatic setup, if the AUTO SET LED is
on, confirmation is not needed to change the FFRT setting.
If no activity occurs for a period of four seconds while the
value is displayed, the FFRT display will disappear and the
old setpoint will take effect.
To exit the menu at any time without saving changes,
simply press the RESET/rE button.
0/4-20mA Output Option
An analog output current is provided for operating a
remote meter or other instrumentation. The load
resistance should not exceed 360 Ohms for the Model 700
signal processors. The resistance can be chosen to give
the desired voltage swing. For example, if 2V is desired for
a 20 mA output, a 100 Ohm resistor would be used. Fig. 26
contains a flowchart for the mA output setup.
The analog current output selections are 0 to 20
milliamps, or from 4 to 20 milliamps. Selection of the
applicable range is made by pressing and holding the 0-
20 MA/4-20 MA OPTION button until the current value is
shown. 02 denotes the 0-20mA selection while 42 denotes
the 4-20mA selection (the default value). While the value
is displayed, it may be changed via the INCREASE or
DECREASE arrow buttons. To store the new setting, press
the STORE button until "- -" is shown, indicating the value
has been accepted.
Confirmation is not requested if the 0-20/4-20 setting is
changed when AUTOSET LED is on.
15 66-2069EP—08