Datasheet Content
SR3 - VE3 - BV3 - GV2
CONTROL BOXES DESCRIPTION
The SR3 - VE3 - BV3 - GV2 safety devices are suitable to
control forced draught gas burners for civil and industrial
CONTROL BOXES FOR FORCED applications.
DRAUGHT GAS BURNERS, WITH The BV3 control is used for fast boilers in which hot water
POWER UP TO 120KW. (or steam) taking has to occur within short times, which
cannot be granted by using the SR3 and VE3 devices.
The GV2 control box is used for small boilers in which a
longer safety time is generally allowed.
According to TÜV Bayern, Monaco, the SR3 control is in
compliance with the German regulation DIN 4788, part 3,
for power up to 120KW. It also obtained the DIN-DVGW
89.11fBN approval, now expired and not renewable.
The “Laboratorio di Macchine e Termotecnica del Centro
Studi ed Esperienze” in Rome, Capannelle, tested the SR3
control for power up to 93KW, which obtained the
certification no. 3704/81/77/3A and the approval of the
Ministry of the Interior for fire prevention (circulars no. 68
and no. 42).
TECHNICAL DATA:
Supply voltage: 220V(-15% +10%)
50Hz (±5%)
on request: 110V
Operating temperature range: -10°C +60°C
Protection degree: IP40
Starting power consumption: 10VA
Operating power consumption: 6,5VA
Max. current rating I max.
- burner motor: 4A
- EV valve: 2A
- ignition transformer: 2A
- alarm: 1A
Regulators (T, PA, PG): 6A
Times:
- prepurge time (TV):
SR3 - VE3: 50 s
BV3 - GV2: 20 s
- safety time (TS): GV2: 15 s
SR3 - VE3 - BV3: 3s
- dropout time on running
flame failure: <1 s
Flame control:
- minimum ionization current: 0,5µA
- recommended ionization current: 7µA
- minimum insulation resistance between
probe, cable and ground: > 50MΩ
- voltage on the detection probe: 300V
Weight including socket: 550 g
FLAME CONTROL
A transformer having one primary and two secondary
windings supplies the electronic flame detection circuit at
low voltage, and the detection probe with about 300V. This
supply system offers the big advantage of having constant
ionization values, even if the network is a live-live
installation.
To check the efficiency of the flame detection circuit, you
have to proceed as follows: connect a low impedance
ammeter, as shown in Fig.1; the R1 ... Rn resistors in
series must give the total resistance value of 200MΩ (e.g.
20 resistors of 10MΩ 1/4W 5%). If the control box is
supplied with 220V, the measured current value is about
0,5+0,6µA DC, which causes the flame relay to switch on.
Lower current values indicate that the circuit is damaged or
only partially efficient.
4009_r00 1/4
Fig.1
CONSTRUCTION
The components of the control box are fixed on a pressed
frame made of thermohardening material, with high
dielectric resistance. The plastic casing protects the device
from possible damages resulting from crashes, incautious
opening, dust and contact with the external environment.
Flexible unipolar conductors of different sizes connect the
components of the control, except for the flame detection
and prepurge control circuit, which is mounted on a printed
circuit.
OVERALL DIMENSIONS
The overall dimensions of the control box are shown in
Fig.2.
(*) The dimensions differ according to
the type of socket: 5 with socket A
9 with socket B
Sockets A - B
Fig.4
h: Dimensions depending on the type
of socket: 95 with socket A
99 with socket B
98.3 with socket N
Fig.2
ACCESSORIES
The control is provided with inbuilt reset button and
luminous lockout signal.
It can be supplied with kanthal flame detection probes in
different executions (see, for instance, Fig.3).
The casing is arranged for the fitting of core hitches and/or
cable holders on its sides; also these accessories can be
supplied on request.
Socket N
Fig.5
Fig.3 DIRECTIONS FOR INSTALLATION
CONNECTION − Control boxes are safety devices and must not be
As regards the interconnection system of this control, opened; the manufacturer’s responsibility and
several solutions are possible and different types of guarantee are invalidated if the control is opened.
connecting sockets can be employed (see Fig.4 and Fig.5). − For safety reasons a regulation shutdown must occur
Socket N differs from sockets A and B for its dimensions every 24 hours.
and the greater number of terminals connecting neutral and − The control can be mounted in any position.
ground.
2/4 4009_r00
− Live and neutral must be connected correctly; a RESET OF THE CONTROL
mistake could cause a dangerous situation. To reset the control after a lockout, act on the button after
− The earth terminal of the control, the metal frame of the waiting for the restoration of the lockout thermal, which
burner, the earth of the ignition transformer and the usually takes about 20 seconds.
earth of the main supply must be well connected.
− Make sure that the discharge of the ignition transformer
ELECTRIC SCHEME SR3
does not hit the detection probe.
− The connecting wire of the detection probe must not be LIVE
longer than 20 m.
− Avoid putting the detection cable close to power or
ignition cables.
− Use a heat resistant cable and detection probe, well
insulated to the ground and protected from humidity or
water in general.
−
FLAME
Always check the control before the first start and also DETECTION
CIRCUIT
after any replacement or after a long period of non-
operation of the system. In particular make sure that:
− The connections are corresponding to the scheme
below.
− The intervention of limiters and safety devices causes a
safety shutdown according to the application.
− The level of the flame signal is high enough.
− A short circuit between detection probe and burner
casing does not cause any flame simulation. NEUTRAL
− In running state, a leakage of the detection probe to the
ground causes the interruption of the oil flow and the
ELECTRIC SCHEME VE3
starting of a new ignition cycle in the case of the BV3
and VE3 controls, while it causes a lockout in the case LIVE
of the SR3 and GV2 controls.
THERMAL TIMERS
The safety time is given by a compensated thermal timer.
The fixed value of 220 V/20°C does not vary of more than
25% with voltage (-15% +10%) and temperature (-10
+60°C) variations. FLAME
DETECTION
The prepurge time is obtained by means of a compensated CIRCUIT
thermal timer too; in the controls type SR3 and VE3 it is
possible to obtain very exact prepurge times even after
frequent and repeated starts of the unit, by exploiting the
bimetal both in the heating and in the cooling stage.
OPERATING CYCLE
When thermostats and gas pressure switch are closed, the
control box starts up the burner motor. During this period
the device carries out a self-check; if the check is positive NEUTRAL
the cycle continues, and at the end of the prepurge stage
the valve and the ignition transformer are simultaneously
supplied. ELECTRIC SCHEME GV2
During the safety time the flame has to become steady,
LIVE
otherwise the control effects a lockout. Consequently, the
valve and the ignition transformer are deenergized, while
the lockout signal is supplied.
If a limiter or regulator is opened, the oil flow is immediately
stopped and the burner is switched off.
The enclosed cycle diagrams are useful for a better
understanding of the operating cycle of each control box. FLAME
DETECTION
CIRCUIT
Abnormal operation:
-…
