HONEYWELL IRIS P522 Flame Monitoring System

F1 (0.75A): Main power supply fuse

F2 (0.25A): Sensor power fuse

When overload occurs, the fuse becomes in a high resistance state and automatically recovers after 10 seconds of power failure.

1. Calculation of power capacity

The total power consumption of each P522 module (with one sensor) is approximately:

Signal processor: 150mA

Sensor: 100mA

Total: 250mA @ 26V ≈ 6.5W

A 30W power supply can support 4-5 modules, a 50W power supply can support 7-8 modules, and a 100W power supply can support 15 modules.

2. Redundant power supply scheme

For high reliability applications, a dual power redundancy configuration can be adopted, isolating two power outputs through Schottky rectifiers (such as MBR1545CT) to prevent single channel faults from affecting the system. Both power supplies can be adjusted to 26V and equipped with a low voltage indicator.

Self checking function and security mechanism

The core security feature of P522 is its self checking function. The system generates a 200ms' dark cycle 'signal per second, which drives the shutter mechanism inside the sensor through the SC terminal to block light. During the dark cycle, the sensor should have no pulse output.

Normal situation: If the number of pulses during the dark cycle is less than 10, the self-test relay remains engaged and the SELF-CHECK O.P. LED flashes.

Fault situation: If the number of pulses in the dark cycle is ≥ 10, the system determines that the sensor or circuit is faulty, enters a locked state, the flame relay is powered off, and the LOCKOUT LED lights up.

Possible reasons for the locked state include:

UV tube out of control (continuous self-excited pulse)

Shutter mechanism malfunction

Electronic component failure

Interruption of connection between sensor and signal processor

The locked state must be manually reset through the front panel RESET button or serial communication command. The reset operation is only effective after troubleshooting.

Set points and operation interface

The front panel of P522 is equipped with a four digit display, LED indicator lights, and five operation buttons (A, B, UP, DOWN, STORE, RESET). Each channel (A or B) can independently set the following parameters:

Parameter display range description

Flame ON threshold ON 0001-2999: If the signal strength exceeds this value, the flame relay will close

Flame OFF threshold OFF 0000-2999: If the signal strength is lower than this value, the flame relay will release

Gain GAIN 00-99 signal amplification factor (digital gain)

Flame fault response time FFRT 1, 2, 3 seconds Delay time for relay release after signal loss

Delay ON DELAY 0, 1, 2, 3 seconds. Delay time for relay to close after flame establishment

1. View and modify setpoints

Press the corresponding button (such as FLAME ON), and the current setpoint will automatically restore after about 4 seconds of display.

Use the UP/DOWN keys to adjust the values, and press the STORE key to save. When saving successfully, display "----", and when saving fails (such as flame OFF threshold ≥ flame ON threshold), display "EEEE".

2. Channel switching

Press the A or B button to switch the current active channel, and the corresponding channel LED will remain on to indicate.

The external CHAN SEL input can remotely select channels, and the flame relay will maintain a cycle during switching to prevent misoperation.

3. 4-20mA output switching

Simultaneously press and hold the UP and DOWN keys, then press the specified combination key to switch between analog output modes:

0-20mA mode: Display "----"

4-20mA mode: display "4-20"

Sensor selection and application guidance

The IRIS S5xx series sensors have been optimized for different types of fuels and burners. The document provides a detailed selection table, and the following are key recommendations:

Sensor model, technology type, applicable fuel characteristics

S506 UV natural gas and low NOx gas have excellent anti-interference ability, but are easily blocked by unburned fuel

S509 dual color (Si+PbS) oil, coal, natural gas Si channel is sensitive to oil/coal, PbS channel is sensitive to all flames

S511 germanium (Ge) has a universal broad-spectrum response, but its anti-interference ability is weak

S512 PbS infrared oil, coal, and natural gas have good linearity, but are prone to saturation at high brightness and require the use of a diaphragm

S550 UV+IR universal dual spectrum, suitable for complex fuels

1. Special considerations for low NOx burners

The flame radiation characteristics of low NOx burners (especially gas burners using flue gas recirculation FGR) change:

Gas low NOx: UV radiation still exists, suitable for S506 or S550.

Low NOx in fuel: The ultraviolet radiation is extremely weak, and infrared sensors (S509, S512) must be used.

2. Application of Orifice

When the flame signal is too strong (such as large boiler oil flames, display value>1800) causing sensor saturation, a diaphragm plate (aperture 3/8, 1/4, 3/16, 1/8 inch) should be installed inside the sensor flange to reduce the incident light intensity and improve the flame ON/OFF ratio.

Communication and Remote Monitoring

P522 supports two communication protocols: