4/13 15491_r01
Electrical installation
−Respect the applicable national and European standards
regarding electrical safety (e.g. EN 60335-1/EN 50165);
−The devices can be equipped with a polarity recognition device.
The non-observance of live-neutral polarity causes non-volatile
lockout at the end of the safety time.
−before starting the system check the cables carefully. A wrong
wiring can damage the unit and compromise the safety of the
appliance.
−make sure that the earth terminal of the control system, the
metal frame of the burner and the earth on the mains supply
are well connected.
−avoid placing the detection cable close to power or ignition
cables;
−use heat resistant detection cables and electrodes, and make
sure that they are well insulated to the ground and protected
from possible moisture or water in general;
−keep the ignition cable as short and straight as possible and
place it far from other conductors to reduce the emission of
electromagnetic interference (max length <2m and insulation
voltage >25kV).
In case of a live-neutral network with unearthed neutral or a live-
live network (with unearthed star centre), the control unit can
operate as well thanks to an inbuilt resistor.
In case of a "partial" short circuit or bad insulation between live and
earth, the voltage on the ionization probe can be reduced until it
causes the lockout of the control unit due to impossibility of
detecting the flame signal.
Checking at start-up
Check the control system before the first start-up, after any
overhaul and after a long period of non-operation. Before any
ignition attempt make sure that the combustion chamber is free
from gas, then check the following:
−if the start-up attempt occurs without gas supply, the control
system should go to lockout at the end of the safety time;
−when stopping the gas flow while the control system is running,
the power supply to the gas valves should be interrupted within
1s, and the control system should proceed to lockout after a
recycling attempt (or more than one up to 10 depending on the
settings);
−operating times and sequence should correspond to those
declared for the type of control unit you are using;
−the level of the flame signal should be high enough (see Fig.4
for the measuring method to adopt);
−the ignition probes should be adjusted in the most stable way
for a spark gap between 2-4 mm;
−the intervention of limiters or safety devices should cause the
lockout or safety shutdown of the control unit according to the
type of application and the procedure provided for.
Microammeter
Fig. 4 – Flame signal measuring method
!
!!
!
The ionization current can be measured in double-electrode control
unit versions only.
In single-electrode versions, inserting a measuring instrument in
series to the detection electrode creates a hazardous situation for
the user.
Operation
The following description refers to control systems with standard
operating cycle.
At every start-up the control system performs a self-checking of its
own efficiency. During the waiting (TW) or pre-purge (TP) time the
internal circuit tests the correct operation of the flame signal
amplifier: extraneous light or a fault in the amplifier leading to flame
simulation prevent the control system from starting.
In the types with fan control, before the pre-purge time (TP) starts,
the air pressure switch contacts are checked to prove their "no-air-
flow" condition. If this test is positive, the air pressure switch
commutation allows the pre-purge time (TP) to begin. The test of
the air pressure switch contacts is repeated at every operating
cycle start-up.
At the end of the waiting (TW) or pre-purge (TP) time the EV1 gas
valve is energized and the ignition device is operated. In this way
the safety time (TS) begins.
If a flame signal is detected at the end of the safety time, the
control unit de-energizes the ignition device and goes to running
condition.
Else, if no flame signal is detected during the safety time, at the
end of the same the control system goes to lockout, the EV1 gas
valve is closed, the ignition device disabled and the lockout signal
energized.
Flame failure during the safety time causes the ignition device to
be activated within one second.
Please see the attached operating cycle diagrams to better
understand the operation of each control unit.
Operating cycle variations
Followings are the available operating cycle variations of the
control units:
−Option 6 (“A”, “B”): ignition mode
The control unit can keep the ignition spark operating for the whole
safety time TS (option “A”) or switch it off immediately as soon as a
flame signal is detected (Option “B”).
−Option 9 (“C3”, “C4”, “C5”): BRAHMA modulating valve type
VCM01 with soft-start function
The soft-start function enables to control the supply current value
to the valve, avoiding its max opening in the following stages:
during ignition (option “C3”); during ignition and the delay time to
reach the second flow rate value (option “C4); during ignition, the
delay time to reach the second flow rate value and in operating
status (option “C5”).
−Option 11 (“X”, “Wnn”): auxiliary fan or auxiliary contact
opening mode
The unit can enable this output at the end of the safety time
(options “X”) or with a delay (expressed in seconds) settable upon
request (option “Wnn”).
−Option 12 (“K”, “Knn”): lockout due to extraneous light
If extraneous light is detected at start-up or during the safety/pre-
purge time, the control unit will proceed to lockout immediately
(option “K”) or with a delay (expressed in seconds) settable upon
request (option “Knn”).
