USA Inc. Carbon Monoxide Alarm User Manual

IRIS MODEL P522 APPLICATION MANUAL
Page 8
A source impedance resistor is required when using
the P522 module with a S550 viewing head. This
resistor should be 330 ohm (factory installed) for
viewing head cable runs up to 500 feet, and it should
be 150 ohm for cable runs 500 feet to 1000 feet.
The resistor should be installed across the SC and SIG
GND terminals. A 1/4 watt resistor is suitable.
Originally, specifications of the IRIS Model 500 in-
structed that a five-conductor cable be used, with
one wire shielded. However, the standard is now a
four-conductor cable, with one wire shielded. In
this case, the shield is used as the signal ground wire
that goes to terminal SIG GND on the P522 and to
pin 3 on the viewing head plug. The shield should
be a braided type for this application –do not use a
foil type shield– so that a solid signal ground is main-
tained. This signal ground shield is also the self-
checking circuit return path. Refer to Figures 2 and
3 for wiring details.
Connections of the IRIS cable to the viewing head
plug should be performed as follows:
After removing the plug from its packaging, take the
cable entry nut out of its housing. Remove rubber
grommet and flat sealing washer. With a pair of long-
nosed pliers, remove the center ring only of the rub-
ber grommet.
1. Strip two inches of the cable’s outer cover
from the cable, removing any cellophane
wrap or filler material, and strip the in-
sulation from the shielded wire (if insu-
lated over shield) a full two inches, to
expose shield.
2. Slide the shield back until a bulge devel-
ops close to where the wire exits the
cable’s outer covering.
3. Carefully spread a few strands of the shield
at the bulge –making sure not to break any
strands– to create an opening, and slip wire
out of shield through opening.
4. Carefully return shield to original shape
and length by pulling gently, then cover
with plastic shrink tubing to prevent shorts.
5. Slide nut (with threads toward the cable
end), the washer and the grommet onto
the cable approximately six inches.
6. Slip the cable through the bottom open-
ing of the connector, making sure that the
cable’s outer jacket is secure under the
cable clamp, and tighten the two screws
on the cable clamp.
7. Reassemble the grommet, flat washer and
cable entry nut, and tighten.
8. Before wiring to connector, strip each
wire 3/8 inch, as shown in assembly dia-
gram, Figure 3.
9. Proceed to wire the connector. Refer to
Figure 2 for terminal locations.
– Connect the viewing head signal wire
WHT (the shielded wire) to terminal
No. 1 by inserting it into the opening,
then tightening the retaining screw.
– Connect the shutter drive signal wire
BLK to terminal No. 2.
– Connect the signal ground shield from
the WHT wire to terminal No. 3 with
shrink tubing.
– Connect the 24 VDC power wire RED
to terminal No. 4.
– Connect the power ground wire GRN
to terminal No. 5.
– Assemble the back of the plug and insert
jackscrew through the plug assembly.
The cable wiring at the other end going to the signal
processor is easier. The cable should be prepared in
a similar way to the plug end – particularly the shield
from the WHT wire. Make sure the shield doesn’t
touch the other terminals.
POWER SUPPLY
Careful consideration should be given to the power
supply used for the P522. 26 VDC is used to back
bias the “steering” rectifier, as shown in Figure 1, to