Honeywell 800 Series Manual page 37

• The Flame Relay will be de-energized when the signal
processor is powered and detects a fault condition.
• The Flame Relay will be de-energized when power to
the signal processor is off.
As an added safety feature, the coil of the Flame Relay is
wired in series with a second pole of contacts on a Self
Check Relay. The Self Check Relay is designed to be closed
during normal operation of the signal processor and open
during detection of a fault or power down. It is physically
impossible for the Flame Relay to be closed if the Self
Check Relay is open, unless the contacts of the Flame
Relay are welded closed or the contacts of the Self Check
Relay are welded closed. To reduce the chance of a false
flame on condition, it is recommended that the user wire
the Flame and Self Check Relays in series.
4.00E -04
3.50E -04
3.00E
-04
2.50E
-04
2.00E -04
PFD
AVG
1.50E
-04
1.00E -04
5.00E
-05
0.00E
+00
0
Fig. 28. Dependence of the PFD
4.00E -04
3.50E -04
3.00E
-04
2.50E
-04
2.00E -04
PFD
AVG
1.50E -04
1.00E
-04
5.00E
-05
0.00E
+00
0
Fig. 29. Dependence of the PFD
HONEYWELL MODEL 700/800 SIGNAL PROCESSOR AND VIEWING HEAD
700 AC PFD
1 2 3 4
AVG
700 DC PFD
1 2 3 4
AVG
37
Also, as another added safety feature, neither relay can be
driven by a simple continuously high or continuously low
signal. Each relay must be driven by an alternating signal
of the proper frequency and duty cycle from the processor.
700AC or 700DC Signal Processor
Proof Test Interval
The Proof test must be conducted every 1 to 5 years. This
range is given to allow for the test to be performed during
the normally scheduled burner shutdown period. It is the
responsibility of the user to perform the proof test in the
specified time frame.
The following diagram presents the dependence of the
PFD on the proof test interval. The PFD
AVG
the proof test interval increases.
VS TIME
AVG
5 6 7
TIME (YEARS)
on the proof test interval for 700AC.
VS TIME
AVG
5 6 7
TIME (YEARS)
on the proof test interval for 700DC.
increases as
AVG
8 9 10
M35037A
8 9 10
M35038A
66-2069EP—08