Safety Function Of The Uniscan 2; Proof Test Procedure; Proof Test Interval - Honeywell U2 User Manual

Safety Function of the Uniscan 2

The safety function of the Uniscan 2 signal processor consists
of a Flame Relay which comprises its safety function and
behaves as follows:
The Flame Relay (Normally Open)
• The Flame Relay will be energized when the product is
powered and a flame on condition is detected for longer
than the time delay value.
• The Flame Relay will be de-energized when the product is
powered, a flame off condition is detected, and the FFRT
(Flame Failure Response Time) has elapsed.
• The Flame Relay will be de-energized when the product is
powered and detects a fault condition.
• The Flame Relay will be de-energized when power to the
product is off.
All Uniscan 2 signal processor models contain a Self Check
Relay designed to be energized during normal operation of
the signal processor and de-energized during detection of a
fault or power down. Due to the logic circuitry which energizes
the coil of the Flame Relay, it is physically impossible for the
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

Proof Test Procedure

EQUIPMENT
• Powered Uniscan 2 signal processor
• Multimeter able to take voltage and resistance
measurements
• 22V DC to 26V DC power supply
• Light source* capable of generating a flame on condition.
* Generally an incandescent bulb will work for IR viewing head
sensors and a deep UV light or flame will work for UV view-
ing head sensors
U2 COMBINATION VIEWING HEAD AND SIGNAL PROCESSORS
1 2 3 4
Fig. 11. 1010 PFD
Flame Relay to be energized if the Self Check Relay is not
energized. To reduce the chance of a false flame on condition
due to welded Flame Relay contacts, 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
signal which could potentially be caused by a fault. Each relay
must be driven by an alternating signal of the proper
frequency and duty cycle from the 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 for the U2-1010 shown for example,
presents the dependence of the PFD
interval. The PFD increases as the proof test interval
AVG
increases.
5 6 7
TIME (YEARS)
over time.
AVG
Setup
1. Ensure the Uniscan 2 signal processor is fully opera-
tional.
2. While performing the proof test, disconnect or disregard
the signal processor outputs so that any outputs due to
testing do not affect the overall safety system and
potentially cause a hazardous situation.
3. Record all previously entered user programmable set-
tings so that you can restore them to their desired val-
ues after the proof test.
23
on the proof test
AVG
8 9 10
M34953
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