Honeywell 700 User Manual page 36

HONEYWELL MODEL 700/800 SIGNAL PROCESSOR AND VIEWING HEAD
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.
Also, as another added safety feature, neither relay can be
driven by a simple continuously high or continuously low
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
66-2069EP—04
700 AC PFD
1 2 3 4
AVG
700 DC PFD
1 2 3 4
AVG
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.
36
increases as
AVG
8 9 10
M35037A
8 9 10
M35038A