page no. 35 of 44
NVx Range Users, Installation & Servicing Instructions issue 6.4 Aug 2017.
P2%
P3%
Drop Out
Volts
5
10
20
30
40
50
60
70
80
90
100
Hold-in Voltage
0
0.3
0.5
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
10
1.0
1.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
20
2.0
2.5
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
30
3.0
3.5
4.0
5.0
6.0
7.0
8.0
9.0
10.0
40
4.0
4.5
5.0
6.0
7.0
8.0
9.0
10.0
5. Turn off the main burner, disconnect the pressure gauge
and replace the sealing screw. Turn on the main burner and
test for gas soundness around pressure test joint using a
leak detection fluid. Replace access panel.
2.6.6.1.4. Modulating Interface Board
Modulating Interface Board
The MIB interfaces between a 0-10VDC control signal and
the modulating regulator. The following are applicable to
this application.
1. The setting of the slide switches 1 & 2 should both be to
OFF.
2. Potentiometer P1 (Default setting 100%)
The control current of the V7335A is controlled by P1,
varying between 50% and 100% of the input signal.
E.g.
-When P1 is set at 100% (fully clockwise) maximum power
(165mA @ 22VDC) is provided to the modulation coil with a
10VDC input control signal.
-When P1 is set at 50% (fully anticlockwise) maximum
power (165mA @ 22VDC) is provided to the modulation coil
with a 5VDC input control signal.
3. Potentiometer P2
Controls the minimum drop-out voltage between 0% and
40% E.g.
- When P2 is set at 0% the drop-out voltage with an input
control signal of 0-10V-DC is 0.3V-DC.
- When P2 is set at 40% the drop-out voltage with an input
control signal of 0-10V-DC is 4.0V-DC.
4. Potentiometer P3 (Default setting 100%)
Controls the maximum hold-in voltage. Its proportional
value is added to the P2 setting E.g.
- When P2 is set at 0% and P3 is set at 5%, the hold-in
voltage of the burner relay is adjustable between 5% and
100% of the input control signal. If the input control signal
is set at 0-10V-DC the hold-in voltage of the relay is 0.5V-
DC.
- When P2 is set at 40% and P3 is set at 5%, the hold-in
voltage of the burner relay is adjustable between 45% and
100% of the input control signal. If the input control signal
is set at 0-10V-DC the hold-in voltage of the relay is 4.5V-
DC.
The following table shows the relationship between P2 and
P3 settings.
