page no. 29 of 44
HEMNVx & HEMSL Range Users, Installation & Servicing Instructions Doc Ref M103 issue 3.6 Mar 2020.
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
3. After the preset 2 minutes of maximum output, the 0 to
10V input signal will take control of the gas valve drive.
4. When the 0 to 10V signal drops below 1V the signal will
drop to zero and the gas valve drive signal will be de-
energised.
The MIB interfaces between a 0-10VDC control signal and
the modulating regulator. The following are applicable to this
application.
1. Slide switches 1 & 2 should both be to 'OFF' if one
modulating valve is being driven (A), switch 1 'ON' and switch 2
'OFF' if two modulating valves are being driven (B)
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.