IRIS S55XX SERIES VIEWING HEADS APPLICATION MANUAL
PAGE 3
INTRODUCTION
For the sake of simplicity, only the operation of the
S550B viewing head in combination with the P522
signal processor will be described in detail. The
S552B and the S556B will be discussed separately in
their respective sections.
The S550B, S552B and S556B can be used with
IRIS Models P531, P532 and later versions of the
Model P520 and P522 signal processors. Refer to
the respective processor manual for connection and
operation not described in this manual.
DIFFERENCES BETWEEN THE S550B AND S550
The Model S550B is basically the same in operation
as the earlier S550, except that a two line numeric
readout replaces the two color LED for displaying
and monitoring the UV and IR count rates. The dis-
played value is the pulse rate divided by 100.
The S550B provides an additional analog output that
can be measured as a current to ground. This can be
achieved by placing a 1000 ohm resistor in series with
the shield and the SGND terminal on the processor,
and monitoring the voltage across the resistor.
If the internal temperature of these viewing heads ex-
ceed 70° C, the temperature will be displayed once
every four seconds.
If the digits “99” are displayed, this indicates that the
IR sensor is saturating. Either reduce the IR “analog”
gain or install an orifice disc. (The IR analog gain is
the first digit of the IR gain).
The IR gain should be set so that the displayed
count is well below the saturation point (34 at the
viewing head, or 3400 at the signal processor) at
maximum firing rate. The signal processor and the
viewing head are designed to “Fail Safe” (Show
“No Flame”) in case of saturation. This may also
cause the pulse counter to start from zero, causing
the flame relay to de-energize.
In some applications, an orifice disk may be required
to discriminate between background radiation and
main flame. See
ORIFICING
on page 9.
SIGNAL PROCESSOR COMPATIBILITY
Viewing heads described in this manual are compat-
ible with currently manufactured P520, P522 DC and
P522 AC signal processors. Some earlier manufac-
tured P522 units may require an upgrade. All P531
and P532 signal processors are fully compatible with
these viewing heads.
Note: Source impedance resistors, 470 Ohm 1/4
Watt must be installed between SC and SGND for all
cable runs between 300 and 700 ft. from the signal
processor to the viewing head.
MODEL S550B GENERAL DESCRIPTION
The IRIS Model S550B is a dual channel, state-of-
the-art flame monitoring viewing head capable of
monitoring both the UV (ultraviolet) and IR (Infra-
red) components of a flame. This is accomplished by
utilizing two types of detectors, an IR solid state sen-
sor and a UV Photo detector, together with a unique
dichroic beam-splitting mirror.
The S550B produces output pulse rates proportional
to the flame signal strength; the pulse rates are dis-
played at the front panel of the signal processor, and
at the rear of the viewing head. The S550B uses a
two line digital readout which displays the pulse rate
divided by 100. The upper readout displays the UV
count in green digits, and the lower readout displays
the IR count in red. This information can readily
be used to achieve maximum flame signal strength
while aiming and sighting the viewing head.
Certain parameters in the S550B, S552B and S556B
viewing heads can be selected or adjusted remotely
from the front panel of the signal processor. These
parameters are:
a) UV gain
0-99
b) Filter Selection
1:
16Hz
2:
24Hz
3:
33Hz
4:
52Hz
5:
75Hz
6:
100Hz
7:
155Hz
8:
215Hz
c) IR gain
0-699
Once adjusted, the new parameters are stored in an
EEPROM in the signal processor. If power is re-