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MX4428 MXP Engineering / Technical Manual Document: LT0273
MXP Loop Filter Board
Page 9-14 24 March 2006 Issue 1.5
Both short circuit faults and open circuit faults will be logged as SUPERVISION FAULT, and
relay stuck faults will be logged as CONTROL CB FAIL. Only the first fault will be logged.
When all relay faults go away, the event logged at the MX4428 will be NORMAL OFF or
NORMAL ON as the case may be, regardless of the original fault logged.
9.11 LPS PROCESSING
9.11.1 ELD AND POSITION MONITORING
Correct Relay Position AI0, AI1 Condition
AI0 > 200 AND AI1 < 50 Open circuit fault
50 < AI0 <= 110 Short circuit
0 <= AI0 <=50 Relay fault
Not activated
Otherwise Normal
AI0 > 50 Relay Fault
AI0 <= 50 AND AI1 <= 50 Short circuit
AI0 <= 50 AND 50 < AI1 <= 200 Relay Fault
Activated
Otherwise Normal
Changes in these states are verified as described in section
9.22.
Both short circuit faults and open circuit faults will be logged as SUPERVISION FAULT, and
relay stuck faults will be logged as CONTROL CB FAIL. Only the first fault will be logged.
When all relay faults go away, the event logged at the MX4428 will be NORMAL OFF or
NORMAL ON as the case may be, regardless of the original fault logged.
9.12 VLC800 PROCESSING
9.12.1 GENERAL
The VLC800 is processed like an 814PH, with the following parameters.
Tracked Value is fixed at 12.
Alarm Threshold is fixed at 100. (Corresponding to a raw value of 112).
Filter Divisor is fixed at 3.
Step Limit is 255 (so essentially there is no step limit).
PreAlarm is adjustable at the MX4428.
So the only filtering is the exponential filter with a filter divisor of 3. This gives some filtering,
but with a minimal delay.
As the alarm threshold is always 100, the current level (CV-TV) is an indication of the smoke
level in terms of % of the alarm threshold programmed into the VLC800 itself.