IRIS Approvals, SELF-CHECKING Function, Powering UP the P522, 1-9, 10 Pulses Counted During

IRIS MODEL P522 APPLICATION MANUAL

modules in a system. Care should be taken when wir- ing multiple P522s to ensure the selected bus wires will carry the current. The plug-in terminals on the P522 will accommodate a wire size up to 14AWG, allowing for relatively high currents. Note that, if the power wiring (26 VDC) is “daisy chained” by using the terminal pairs provided, the pairs are “jumpered” by copper traces on the mother board; so, if the plug is pulled out, the jumpered connection is broken.

has been corrected, and can be performed from the front panel (by pressing the RESET button), or re- motely through the serial communication.

APPROVALS

The P522 and viewing heads have Factory Mutual (FM) Approval for Combustion Safety; Canadian Standards Association (CSA) Certification, and National Recog- nized Testing Laboratories (NRTL) Listing.

SELF-CHECKING FUNCTION

When energized, the self checking function indicates that both the P522 and the viewing head are func- tioning properly. The software in the P522 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.)

A runaway UV tube or any component failure, in- cluding the shutter, will cause a lockout condition that will de-energize the flame relay. The LOCKOUT light on the P522 will indicate this condition, requiring a reset to return to normal flame monitoring mode. A reset can be achieved only if the lockout condition

POWERING UP THE P522

Once the power is connected (26 VDC) to the plug-in connector, the P522 will be operational. There is no ON/OFF switch on the P522; the moment it is pow- ered on, it will reset and start up. The self-checking light will start blinking, and one of the channel LEDs (A or B) will light (A will be ON if the channel select input at the plug-in connector is de-energized). Make sure the voltage is 24 to 26 VDC. The P522 will be reset when the power is turned on; however, the power must be a step function (i.e., the power must be ap- plied abruptly) for this reset to work properly.

The P522 has been designed to deal with any fore- seeable power failure or anomaly.

For example: if the power goes off while you are in the process of storing a set point (either from the front panel or from the remote, host computer), the internal power monitor circuit will signal the P522 processor to complete the store function before shutting down in an or- derly manner. This prevents bogus num- bers from being stored and protects ex- isting data in the EEPROM (Electrically Erasable Programmable Read Only Memory) from corruption, and is facili- tated by a special internal power supply that holds a charge (like a battery) just long enough to allow the processor to do its job before going dead.

This internal circuit monitors the 26 VDC power feeding the P522, and when the voltage drops to about 19 volts, the processor shuts down, the pro- gram stops running, and the self-checking function ceases (the self-checking relay de-energizes). The

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