14
Pre-ignition time (option Jnn):
1 ... 60 s
Cycle repetition attempt
(option Ynn):
1
...
10
Maximum cable length of external
components:
OpenTherm ™
interfaces:
50
m
Flame control
The flame detection device uses the righting
property of the flame.
As an important safety aspect, it should be noted
that the control device is more sensitive to flame at
start-up or during waiting / pre-purge time (negative
differential switching).
Minimum ionization current: 0.5 μA
System temperature probes
- Regulation probe (SR)
The control probe is designed to detect the
temperature of the heat exchanger and is mainly
used by the NTC dual-sensor FAN heating function
(version standard):
in this case the probe has a double function as it
avoids the use of the safety thermostat.
It will therefore be used both for temperature control
functions and for safety functions ( safety shutdown
due to excessive system temperature).
For this purpose it is necessary to use the BRAHMA
probe type ST16 (fig.3).
Ambiance sensor (SA)
The room probe (optional) can be used if the remote
temperature control (BRAHMA chrono thermostat
type ENCRONO GA1) is not in the area where you
want to implement thermoregulation or in cases
where it is necessary to relate the latter to the
temperature of the environment external.
For more details about the functions in which this
probe is used, refer to the section
“OPERATION”
For this purpose it is necessary to use the BRAHMA
probe type ST07 (for the detection of the local
ambient temperature) or the BRAHMA probe type
SSE (for the detection of the external ambient
temperature).
Fire damper (STF)
Through this input (option S) it is possible to check
the contact status of the fire damper: in case this
consent was open (fault condition) the ignition cycle
it is interrupted by bringing the device into the
waiting position, signaling the error by means of
LEDs.
On request, the behavior of the equipment in case
of opening of the contact can be modified according
to customer specifications.
4.4 CHECKS STARTING UP
Carry out a check of the device when it is put into
operation for the first time, after each revision and
after the system has been inactive for a long time.
Before any ignition operation, check that the
combustion chamber is free from gas, therefore
check that:
- if the start-up attempt is implemented without
gas injection occurs a blocking stop at the end of
the security time;
- interrupting the flow of gas with the appliance in
the operating position, voltage is removed within
1s to the gas solenoid valves and, after a
repetition of cycle (or more cycle repetitions up to
a maximum of 10, depending on the settings),
the device make a block stop;
- the times and the cycle comply with those
declared for the type of device used;
- the flame signal level is sufficient high (see Fig.4);
- the ignition electrodes are adjusted
stably for a discharge distance in air between
2 and 4 mm;
- the intervention of limiters or safety devices
cause the safety lock or shutdown of the appliance
according to the type of application and the
procedures laid down.
Connection of the double NTC probe
Brown
black
blue
Fig. 3
Fig. 4
Measurement of the flame signal
Microampere
