I.R.I.S. FLAME MONITORING SYSTEM P522 User Manual
Page 5
IRIS MODEL P522 APPLICATION MANUAL
Page 5
WIRING TO THE PLUG-IN TERMINALS
Figure 1 illustrates the plug-in terminals on the rear mother
board and how they are connected internally. The flame
relay and self-checking relay contacts are situated together
in the upper right portion of the diagram.
RF C refers to the common terminal of the flame relay,
with ON being flame on, and OFF being flame off. You
will note that there are two sets of contacts used for the
flame relay.
SC C refers to the common terminal of the self-check-
ing relay. There is only one pair of contacts used
for the self-checking function. Here, the designa-
tion ON refers to the self-checking taking place in a
normal manner. OFF indicates a failure in the view-
ing head or processor resulting from:
-
the hardware (i.e. the shutter mechanism in
the viewing head, or the output relay itself);
-
electronic components anywhere, or
internal software in the P522; or
-
the power to the unit is OFF – the most
likely condition.
The main power feeds in through the terminals situ-
ated on the upper left side (see GND, +26V and BAT).
Each designated terminal is a double terminal, or pair,
so that the wiring from the power supply can be “daisy
chained” from one P522 to the next without having to
twist wires together into one termination.
The pair designated BAT is for battery backup, if
used. Note the rectifier used internally to prevent
the 26 VDC main power supply from feeding into
the battery. The backup battery, if used, should be
24 volts, to ensure that the 26 VDC power feeding
the P522 will not feed back into the battery. In other
words, no current will flow from the battery as long
as voltage of the main power supply is above that of
the battery. The negative side of the battery goes to
the GND terminal on the left.
Figure 1 shows how these terminals are connected
inside the P522. Note the two fuses marked F1 and
F2. F1 is the main power fuse for the signal proces-
sor as well as the viewing head(s), and is rated at .75
Amp. Fuse F2 feeds only to the viewing head(s),
and is rated at .25 Amp. On newer units (those with
NO, CAL, and YES in red letters on the front panel)
these fuses are self-resetting types, and will recover
from an overload automatically after power is re-
moved from the P522 for 10 seconds.
The viewing head terminals (bottom right) are iden-
tified as V.H. A. and V.H. B. If only one viewing
head is used, you must wire to the V.H. A. termi-
nals. To the left of the viewing head terminals are
two terminals marked V.H. SEL (viewing head se-
lector relay). Energizing this connection with 19 to
38 VDC will cause the relay on this PC board to
switch to viewing head B. The nominal voltage of
this relay is 24V, but the 26 VDC power circuit can
be used to switch this relay, if desired.
Only the viewing head signal wire (SIG) and the sig-
nal ground wire (SIG GND) are switched with this
changeover relay; the 26 VDC and power ground
circuit is not disturbed. Make sure that the viewing
head signal wire and signal ground (braided shield
in the four-conductor cable) are both connected, be-
cause this ground connection is the only return path
for the signal and self-checking circuit. Also, the 26
VDC used to switch this relay must be connected
with the proper polarity, because the relay used is a
single-side stable type. (Relays that are polarized
magnetically offer increased contact force resulting
in higher current-carrying capability). The two ter-
minals marked V.H. SEL go directly to the relay coil.
The pair of terminals designated CHAN SEL (to the
left of the V.H. SEL terminals) is used for selecting
channel A or channel B on the P522. Energizing
this pair of terminals causes the B channel to be se-
lected. Polarity must be observed when wiring this
connection (the positive terminal is on the right).
This is an isolated input, so two wires are required.
Any DC voltage from 7.5 to 30 may be used. The
current required will depend upon the voltage, be-
cause this is a photocoupler interface circuit with a
3900 ohm resistor feeding the LED light source.
For example: a 26 VDC voltage will result
in a current flow of 25/3900 = .0064 Amp.
If flame is being detected and the channels are
switched, the flame relay will remain energized for