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Publication No. 1-07-184
 download this Tec-Note in PDF format
Pages: 1, 2, 3, 4, 5, 6, 7, 8
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| SHOCK HAZARD. High voltage is present on certain terminals inside the main control panel, inside the mod motor and inside the burner panel. Touching them will cause death or serious injury.
Do not work on these components unless you are a qualified technician familiar with the hazards of electricity.
Some circuits in the main control panel may receive power from remote sources. Thus, the breaker operator on the door may not deenergize all exposed live parts.
Always use a voltage tester to make sure there is no voltage on the terminals or bare wires you may touch.
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Interaction with Fireye flame monitor (Figure 3)
The Fireye flame monitor monitors the open/closed status of the low-fire and high-fire proof switches in the mod motor while the burner is being purged. The low-fire proof switch is wired between terminals M and D. The high-fire proof switch is wired between terminals D and 8. Thus, the flame monitor shows either M-D LIMIT or D-8 LIMIT when indicating the status of these switches. Each switch is activated and de-deactivated by its own rotating cam in the mod motor.
- On mod motors with a red low-fire cam the low-fire proof switch remains in its normally closed position while the damper is fully closed. After the damper begins to open, the cam opens the switch.
- On mod motors with a blue low-fire cam the cam holds the low-fire proof switch in its closed position while the damper is fully closed. After the damper begins to open, the cam opens the switch.
- On all mod motors, the high-fire cam closes the high-fire proof switch when the damper reaches a preset open position. After the damper begins to close, the cam opens the switch.
Figure 3. Fireye flame monitor.
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Interaction with Honeywell modulation controller (Figure 4)
The modulation controller controls the mod motor using a circuit that provides an output of 4 to 20 mA. With a 4 mA signal the mod motor should be in the low-fire position with the damper fully closed. With a 20 mA signal the mod motor should open the damper to the high-fire position.
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