Cams And Trim Potentiometers Functions; Flame Signal Measurement; Preliminary Inspection; Measuring Flame Signal With Keyboard Display Module - Riello RL 190/M Installation, Use And Maintenance Instructions

5.4.1

Cams and trim potentiometers functions

Cam 1: 130°
Limits rotation towards maximum for oil
Cam 2: 0°
Limits rotation towards minimum, air damper closed on
stand by
Cam 3: 20°
Limits OIL ignition position and minimum position
Cams 4 - 5 - 6 - 7 - 8: not used
Disconnect the control power supply and the main
electrical supply to the servomotor before perform-
ing any service functions.
WARNING
5.5

Flame signal measurement

5.5.1

Preliminary inspection

Make certain that:
– wiring connections are correct and all terminal screws and
electrical connections are tight.
– Proper flame failure response time is selected.
– Min value for a good signal: 1.25 Vdc.
– Max expected value: 5.0 Vdc.
5.5.2 Measuring flame signal with keyboard display
module
Consult Instructions for applicable 7800 SERIES Relay Module or
Keyboard Display Module (Fig. 39).
S8159
5.5.3

Measuring flame signal with a volt ohmmeter

Two test jacks, positive and negative (Com) are accessible on the
top of the amplifier when plugged into the 7800 SERIES Relay
Module. These jacks are provided for monitoring flame signal
strength. Use a one megohm/volt meter to measure the flame sig-
nal strength.
Connect the positive meter lead (red) to the positive (+) amplifier
test jack and the negative meter lead (black) to the negative (-) am-
plifier test jack. The test jacks use standard 0.180 inch diameter
voltmeter probes. A minimum 1.25 Vdc flame signal is required.
The flame signal for the pilot alone, the main burner flame alone,
and both together must be steady and a minimum of 1.25V. If the
flame signal is unsteady, or less than the minimum acceptable volt-
age, check the flame detector installation and circuitry in the follow-
ing procedure.
➤ Check the supply voltages at terminals (L1) and L2 (N). Make
sure the master switch is closed, connections are correct, and
Start-up, calibration and operation of the burner
Fig. 39
27
the power supply is of the correct voltage and frequency and is
sinusoidal.
➤ Check the detector wiring for defects including:
– incorrect connections
– wrong type of wire
– deteriorated wire
– open circuits
– short circuits
– leakage paths caused by moisture, soot or accumulated dirt
➤ For a flame rod, make sure:
– There is enough ground area.
– The flame rod is properly located in the flame.
– Temperature at the flame rod insulator is no greater than
500°F (260°C).
➤ For all optical detectors, clean the detector viewing window,
lens, and inside of the sight pipe as applicable.
➤ With the burner running, check the temperature at the detec-
tor. If it exceeds the detector maximum rated temperature:
– Add a heat block to stop conducted heat traveling up the
sight pipe.
– Add a shield or screen to reflect radiated heat.
– Add cooling (refer to sight pipe ventilation in the detector In-
structions).
➤ Make sure that the flame adjustment is not too lean.
➤ Make sure the optical detector is properly sighting the flame.
➤ If necessary, resight or reposition the detector.
➤ If you cannot obtain proper operation, replace the plugin
amplifier.
➤ If you cannot yet obtain proper operation, replace the flame
detector.
If you make any changes to the flame detection sys-
tem, repeat all required Checkout tests in the In-
structions for the applicable Relay Module.
WARNING
GB
D10732
Fig. 38
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