Merlin PM2+
User Guide
Rev: 2 05-19
5
3
How to setup the current monitors
3.1
Setting the minimum & maximum fan current.
Turn Fan 1 (F1) switch to ON position.
The LCD screen will show Fan 1 current.
! - means Fan1 has not yet been calibrated.
Set Fan 1 minimum operating current.
Press and hold the F1 LOW button.
LCD screen will display: F1 LOW SAVED.
Set Fan 1 maximum operating current.
Press and hold the F1 HIGH button.
LCD screen will display: F1 HIGH SAVED.
Please repeat steps to set min & max current of Fan 2.
IF YOU ARE ONLY INTERLOCKING WITH ONE FAN, PLEASE LEAVE THE REMAINING [F] SWITCH
TO THE ‘1’ or ‘OFF’ POSITION TO PREVENT NUISANCE TRIPPING.
If the measured current falls below or rises above 10% of the permitted current, the LCD display
will show a ‘LOW!‘ or ‘HIGH!’ message next to the relevant fan and the gas solenoid valve
connected will be isolated. To adjust this threshold – see following section.
To erase the calibration data press and hold the relevant [RESET] button until ‘!’ appears.
3.2
How to adjust the current monitor thresholds.
The PM2+ has a factory set 10% dropout threshold for low and high values for both fans.
However, it is possible to alter between a 10% to a 40% dropout threshold if required.
Follow these instructions
1.
Switch F1 and F2 switch OFF.
2.
LCD will display ‘F1 and F2 OFF’
3.
To change the LOW threshold, press and hold F1 and F2 LOW buttons together
4.
The LCD screen will display ‘Offset L F1 10%’
5.
Select different thresholds by pressing the F1 LOW button
6.
After 5 seconds of inactivity the LCD screen will display the new low offset value for F1 (fan 1).
7.
Once Fan 1 threshold has been set the LCD screen will prompt setting fan 2 ‘Offset L F2 10%’.
8.
Repeat step 4, 5, 6 as above for Fan 2.
9.
Once this has been setup the LCD screen will display the new low offset value for F2 (fan 2).
F1! 10.0A
F2 OFF
F1 LOW
SAVED
F1 HIGH
SAVED
F1 LOW!
F2 10.5A
