Siemens LME7 Series Technical Instructions page 128

Technical Instructions
Document No. LME-1000
Honeywell Modutrol IV with the LME75 (continued)
7. Main valve output X7-04.4 is energized in phase 50 (for piloted burners) or phase 40 (for
non-piloted burners). Input X5-03.3 is energized, which has no effect. Output X2-09.3 is
de-energized, so normally open contact CR-1B remains open, and relay CR-2 remains de-
energized. The mod motor remains at the low fire position. The LME75 lights off the
main burner and progresses through the end of phase 52 like this.
8. The LME75 transitions to operation phase oP. During phase oP, power on input
X5-03.3 is directly transmitted to output X2-09.3, causing relay CR-1 to energize.
Normally open contact CR-1B closes, energizing relay CR-2. Normally open contact CR-2
closes, allowing the modulation signal (0-135 Ohm or 4-20 mA) to control the mod
motor. Normally closed contact CR-2 opens, preventing the connection of terminals R
and B on 0-135 Ohm mod motors or terminals F and - on 4-20 mA mod motors. During
phase oP, the mod motor is controlled by an external control signal, and the LME75
does not require any type of position feedback.
9. The LME75 loses the call for heat and transitions to phase oP1. Output X2-09.2 is
energized to drive the mod motor to low fire before shutting the fuel valves. Once the
mod motor reaches the low fire position, the low fire proving switch closes, and
actuator feedback input X2-09.4 is energized.
10. Postpurge (phase 74) occurs at low fire. No actuator position feedback is required
during postpurge.
11. Output X2-09.1 is energized in phase 10 to drive the mod motor to low fire. Since the
mod motor is already at the low fire position, the low fire proving switch is closed, and
actuator feedback input X2-09.4 is energized.
12. The LME75 transitions to standby, displayed as "OFF" on the LME75 and AZL23.
Appendix A Page 6
LME Series
SCC Inc.