IRIS P520, Руководство по применению

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IRIS MODEL P520 APPLICATION MANUAL
Page 10
FACTORY STOCKED POWER
SUPPLIES
Power supplies are readily available from the fac-
tory for the P520 modules. The IRISPS030 power
supply will support up to three P520 modules with
one viewing head each. The 50-watt power supply
will power up to six or seven P520 modules with
one viewing head each (30 watt). The IRISPS050
power supply will support up to six P520 modules
with one viewing head each (50 watt). And the
IRISPS100 will power up to twelve P520 modules
with one viewing head each (100 watt). These
“switching type” power supplies are efficient and
very compact. 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 P520 signal
processors be supported by one 26 VDC power sup-
ply. For instance, four P520 processors with one
viewing head each equals a total of 31.2 watts – a
relatively small power supply, particularly if an ef-
ficient, 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
P520 signal processors.
For example: the 100-watt power supply
available from the factory can handle
twelve P520 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 applica-
tion. 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
P520 modules in a system. Care should be taken
when wiring multiple P520s to ensure the selected
bus wires will carry the current. The rear PCB on
the P520 will accommodate a wire size up to
14AWG, allowing for relatively high currents.
SELF-CHECKING FUNCTION
When energized, the self checking function indicates
that both the P520 and the viewing head are func-
tioning properly. The software in the P520 activates
the self-checking relay only if there are less than 10
pulses coming in from the viewing head during each
dark period. To energize this relay, the software must
generate pulses –at a particular rate and with a spe-
cific duty cycle– to a self-checking circuit. If this
regular pattern is not maintained, or if any of the
circuitry fails, the relay will drop out. The blinking
LED on the front panel labelled SELF-CHECK O.K.
is evidence that voltage is applied to the coil of this
self-checking relay, because both are energized by
the same voltage. The difference is that the voltage
to the coil is applied steadily, while the voltage from
the relay to the LED is gated on and off by the soft-
ware in conjunction with the pulses counted during
the dark period.
Note that, with regard to the viewing head, the self
checking function still works the same way as with
the M502, A513 and D504 signal processors. For
instance, a runaway UV tube will cause a “lockout
condition” (more than 10 pulses counted during the
dark period). (Refer to section EXPLANATION
OF 1-9, > 10 PULSES COUNTED DURING THE
DARK PERIOD, in the Model 500 Signal Proces-
sor Application Manual.)