Datasheet Content
SIT Group
537 ABC
Subject to change without notice
537 ABC - ELECTRONIC FLAME
CONTROL DEVICE FOR INTEGRAL
MOUNTING ON SIT SIGMA
MULTIFUNCTIONAL CONTROLS
9.955.486 108
w w w . s i t g r o u p . i t
537 ABC
DESCRIPTION
The 537 ABC is an electronic flame safety device for controlling a gas appliance using
the principles of flame rectification.
The 537 ABC automatic device has been designed for domestic gas appliances with or
without a fan in the combustion circuit; with direct ignition or ignition by means of an
intermittent pilot in applications which require either non-volatile or volatile lockout.
The 537 ABC family of products has been specifically designed for fixing on SIT 840,
845 and 848 SIGMA multifunctional controls by means of an exclusive plastic container
which integrates itself with the valve body and simplifies connection of the solenoid
valves.
APPLICATIONS
The 537 ABC is an automatic ignition control for applications with intermittent
operation in accordance with EN298 for:
- boilers with natural draught
- boilers with forced draught including dynamic control of the air pressure switch.
NORMATIVE REFERENCE
EN 298
Automatic gas burner control systems for gas burners and gas-burning appliances
with or without fans.
BASIC FEATURES
- Compact design
- Direct assembly on the gas control
- Incorporated igniter
- Direct burner ignition (DBI) or by intermittent pilot (IP)
- Manual reset function and remote signalling of the non-volatile lockout state
- Multiple plug-in connectors
- Utilises well established electronic technology for high reliability of operation
- Precise and repeatable timing
- Flame detection by ionization
- EC approval according to EN 298 standard
- Repetition of the cycle after loss off flame during operation
- Permanent lock-out visualization, a without thermostat input being present
- Suitable for applications at low ambient temperatures
Options available
- Fan and air pressure switch control
- Volatile lockout version for specific applications
- Possibility to connect an automatic safety thermostat in series with the
solenoid valve with manual lockout following its operation
- Different flame current sensitivity options may be specified
- Protection rating IP44
- Several pre-purge and safety timings can be tailored to the application.
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537 ABC
OPERATION
Normal operation (natural draught or fan assisted)
BOILERS WITH
During the waiting or purge time, Tw or Tp, the unit verifies that there is NATURAL DRAUGHT
DBI version
no parasitic flame signal present, and that the internal circuitry is
operating correctly. If the unit is used on a fan-assisted application, the
air pressure switch is verified to be in the N.C. (normally closed) or MV
“no flow” position. VN
Upon powering the fan, the unit will not begin the operating sequence
until the N.O. (normally open) or “flow” position is activated on the air
pressure switch. After the scheduled waiting time Tw, or purge time Tp,
the built-in igniter and the gas valve are energized. This commences the TW TW TS
safety time, Ts. The ignition spark will ignite the gas and the flame will
be sensed by the HV electrode.
BOILERS WITH
Upon sensing the flame, the HV spark will be suppressed and the gas NATURAL DRAUGHT
valve will remain energized. When the thermostat is satisfied, the valve IP version
and fan are de-energized and the control returns to the stand-by mode.
The safety time of the 537 ABC has a constant duration in all operating
EV1
conditions and, in particular, does not depend on the moment the
pressure switch is switched over. EV2
VN
Resetting the unit
To reset the unit the reset switch is depressed. If a first reset is not
TW TW TS
successful, wait at least 10 seconds before the next attempt.
FAN ASSISTED BOILERS
DBI version
WIRING DIAGRAM
EV
VN
P
TP TP TS
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537 ABC
TECHNICAL DATA
AMBIENT WORKING TEMPERATURE
-20 TO + 60 °C
HUMIDITY
95 % max at 40 °C
SUPPLY VOLTAGE
230 Vac - 15 %, + 10 %, 50-60 Hz
POWER CONSUMPTION
10 VA
ELECTRICAL RATINGS
Gas valves: 230 Vac, 0.5 A, cosϕ≥0.4
Fan: 230 Vac, 1 A, cosϕ≥0.4 (optional)
Allarm: 230 Vac, 1 A, cosϕ=1
ELECTRICAL CONNECTIONS
High voltage probe: male fast-on connector 2.8 mm X 0.5 mm
Flame detection probe: male fast-on connector 4.8 mm X 0.8 mm
Other connections: male Molex series 2599 suitable for female Molex series
3001 and 3002 or compatible.
PROTECTION DEGREE
Standard IP 40
IP 44 with gaskets
TIMING
Minimum waiting time Tw or purge time Tp: 1.5 ... 40 sec.
Maximum safety time Ts: 3 ... 60 sec.
FLAME SENSING
Minimum flame current: 0.5µA
Recommended flame current: > 3 times the minimum current
FUSING
Internal: 4 A fast.
External: 3.15 A fast or less depending on the electrical loads. This fuse protects
the device in the event of overloading or short circuits and prevents the
intervention of the internal fuse.
IGNITION
Ignition voltage: 15 KV at 30 pF load
Repetition rate: 25 Hz standard (1 : 25 Hz)
Max. length of the cable: 2 m
Spark gap recommended: 2-4 mm
MOUNTING
Integrated on SIT SIGMA multifunctional gas controls.
DIMENSIONS- 537 ABC with 845 SIGMA VERSION G3/4 ISO 228
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