Factory stocked power supplies, Redundant power supplies, Figure 4 - power supply table – I.R.I.S. FLAME MONITORING SYSTEM P522 User Manual
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IRIS MODEL P522 APPLICATION MANUAL
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prevent the power from feeding into the 24 VDC
supply. Each P522 module draws approximately 150
mA, and each viewing head draws about 100 mA of
power (26 VDC). Actually, the S506 and S511 view-
ing heads use less current, but it is a good idea to
figure 100 mA for each viewing head used. Also,
the amount of current drawn by the P522 will de-
pend upon other factors that can affect the peak cur-
rent, such as whether or not there is flame being de-
tected, the remote meter output is connected, and se-
rial communication is occurring.
The viewing head is powered through the P522 via a
0.25 A self-resetting fuse. In other words, the 26
VDC power feeds into the P522 (through a 0.75 A
self-resetting fuse) and feeds back out through a 250
mA fuse to the viewing head, resulting in a current
drain of about 0.25 A for each P522 (with one view-
ing head). This small amount of current means that
one power supply could support a number of P522
modules. The self-resetting fuses change to high re-
sistance when their current ratings are exceeded, but
recover to their normal low resistance when power
is removed.
FACTORY STOCKED POWER SUPPLIES
Power supplies are readily available from the fac-
tory for the P522 modules. The 30-watt power sup-
ply will support up to six or seven P522 modules
with one viewing head each. The 50-watt power
supply will power up to six or seven P522 modules
with one viewing head each. And the 100-watt power
supply will support up to fifteen P522 modules with
one viewing head per each 100 watt. These “switch-
ing type” power supplies are efficient and very com-
pact. To obtain the size and weight of the power
supplies, contact IRIS Systems Inc.
Each power supply can be either rail mounted or
panel mounted, and it is up to each end user to deter-
mine their installation preferences and requirements.
We recommend that not more than four P522 signal pro-
cessors be supported by one 26 VDC power supply. For
instance, four P522 processors with one viewing head
each equals a total of 26 watts – a relatively small
power supply, particularly if an efficient, switching
type is used.
Other possible combinations can be used; for in-
stance, the battery backup terminal could be used
for redundancy. However, care must be taken with
these redundant schemes to make sure that failure of
the primary power supply won’t affect the backup
power supply, as well.
REDUNDANT POWER SUPPLIES
It may be more economical to use larger-capacity
power supplies for applications using 12 or more
P522 signal processors.
For example: the 100-watt power supply
available from the factory can handle
twelve P522 modules, each with one view-
ing head. Should the power supply fail, a
redundant scheme utilizing two power
supplies with “steering” rectifiers to pre-
vent current from flowing into a failed
power supply output would prevent the 12
flame monitors from being de-energized.
The positive output from each power supply is wired
to the anodes of the MBR 1545CT. This dual,
Schottky-type rectifier, rated for 15 Amps, will present
a low forward voltage drop for this application. Both
power supplies can be adjusted for 26V output, and a
low-voltage indicator light can be used on the output
of each power supply to monitor their outputs.
Larger power supplies can be used with this redun-
dant wiring scheme if there are more than twelve P522
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FIGURE 4 - POWER SUPPLY TABLE