U2 COMBINATION VIEWING HEAD AND SIGNAL PROCESSORS
66-2071—02
6
Locking coupler (R-518-CL12-HTG)
– Used with the R-518-
PT12 and R-518-PT12L insulating locking coupler adapters.
Process connection end is 1 in. NPTF.
Connector (R-518-10)
– Quick disconnect connector for all
non-pipe fitting U2 models.
NOTE: Connector is not included with the non-pipe fit-
ting models. Order separately along with cable
and required mounting accessories.
Cable (C12S)
– 12 conductor cable with braided shield. Sold
per foot.
NOTE: Cable is not included with the non-pipe fitting
models. Order separately along with connector
and required mounting accessories.
Cable+ Connector (ASY964)
– Pre-assembled 15-foot
(4.7m), 12-conductor cable (C12S) with quick disconnect (R-
518-10) for all U2 non-pipe fitting models.
Fiber Optic System Compatibility
– The U2 models are
compatible with the Honeywell FASA fiber optic extension
products. The S550FOAD, S550FOADY-FT and S550FOADY-
FT-AL adapters are applicable. Contact your distributor or
Honeywell for assistance with fiber optic selection and pricing.
USB to RS422/RS485 Converter (COMMOD)
– Protocol
converter for use with external communication to a remote
computer.
OPERATION
IR and UV Detectors
See Table 1 on page 2 to determine which sensors are active
in your U2 model.
The UVTron tube sensor responds to UV radiation from
different fuel flames. The UVTron sensor generates pulses
that are electronically conditioned to provide output indicated
on the U2 display from 0000 to 3425 units.
The signals from the UVSS solid state sensor are processed
based on flicker principle using FFT (Fast Fourier Transform).
User selectable high pass filters are used to reject signals that
are from background radiation.
The signals from the IR solid state sensor are processed
based on flicker principle using FFT (Fast Fourier Transform).
User selectable high pass filters are used to reject signals that
are from background radiation.
Each sensor allows independent adjustment for gain. For
flicker-based sensors, there is also a high pass filter setpoint.
To further assist in flame discrimination setup, adjustable
“Flame On” and adjustable “Flame Off” thresholds are also
provided. The Flame On threshold and Flame Off threshold
can then be set to monitor the target burner flame but to reject
background radiation from other burners.
In order to energize the flame relay, the flame count must be
higher than the programmed “Flame On” threshold for greater
than the “Time Delay” value. Once the flame relay is
energized, the flame signal can fall below the programmed
Flame On threshold setting. As long as the flame signal
remains above the programmed “Flame Off” setting, the
system will continue to operate. When the flame signal falls
below the programmed “Flame Off” threshold, it will not be de-
energized until after the “FFRT” (flame failure response time)
expires, unless “Flame On” is detected.
The U2 includes a self check relay which should always be
energized whenever the U2 has power. The self check relay is
de-energized (failsafe) when an internal fault is detected. The
self check relay is factory wired in series with the flame relay.
One additional contact is provided for alarm purposes.
Self-Checking
There is a small processor in all viewing heads and it is
possible that it could fail and produce erroneous viewing head
pulses. The self-check circuitry guards against such an
occurrence. There are several tasks that require intelligent
interaction between the viewing heads and the signal
processor. If all of the interactions do not occur properly, the
flame relay will open.
User Interface
A touch wheel located on the back of the U2 is used for
operator interface. The configuration menu is simple and easy
to follow. Full character 4 digital scrolling LED displays are
visible in the dark or sunlight. Individual sensor LEDs (3 total
located below the display) flash to indicate the output of each
sensor (green = UVT, Blue = SSUV, Red = IR). The upper
right green self-check LED provides status of the hardware
while the upper left red “Flame On” LED provides status of the
flame relay (main safety device).
NOTE: The number of LEDs is model dependent.
The touch wheel is designed like an iPod
™
to allow for slow or
fast changes by moving a finger slower or faster around the
back glass. Alternatively the user may tap
(-) or
(+) to
make changes. Tap
ENTER/STORE
to enter a menu or store
selected data. Tap
BACK
to return to the previous menu. Exiting
all the menus will display the current flame count. The U2
menus are detailed below.
