BRAHMA EUROGAS Series User manual

EUROGAS SERIES
TYPES VM41 VM42
AUTOMATICCONTROLSYSTEMSFOR FORCED
DRAUGHT BURNERS FOR GASEOUS FUELS
DESCRIPTION
The automatic control systems ofthis series are suitable to
control forced draught burnersfor gaseous fuels for non-
permanentoperation.
All these controls perform non-volatile lock-outs,condition
from which arestart of the system is only possible by
means ofthe control manual reset.
This range of controls is suitable to equip burnersfor
domestic and industrial heating. The VM41 control is
suitable for single flame applications,while the VM42
control is suitable for dual flame applications.
GENERAL FEATURES
The main features of this range are the following:
− EC - Type certification (CE Reg. N° 63AQ0625) in
accordance with Gas Appliance Directive 90/396;
− in accordance with EN 298 (European standardfor
automatic gas burnercontrol systems), prEN 676
(European standardfor automatic forced draught
burners) and DIN 4788 (German standard for automatic
forced draught burners);
− flame monitoring by the rectification property of the
flame (ionization);
− twoindependent safety contactsforthe gas valve
control;
− electrical service lifeat max.declared loading >250.000
operations;
− inbuilt manual reset;
− easy to install and wire;
− interchangeable with the relevant mechanical controls
as regards operation and dimensions;
− max. burner outputfor VM41:
120KWaccording to prEN 676;
350KWaccording to DIN 4788;
− max. burner outputfor VM42: no limits.
TECHNICAL DATA
Power supply: 230V-50/60Hz
upon request: 110/120V-50/60Hz
Operating temperature range: -20°C +60°C
Ambient humidity: 95% max. at 40°C
Protection degree:
socket type NE IP 40
socket type N IP 40
Classification code (according to EN 298):
VM41 FMCLXN
VM42 FTLLXN
Flame failure during TS causes spark restoration.
Times:
-Prepurge time (TW) 20/30/40/50/60 s
-Safety time (TS):
VM41: 2/3/4/5 s
VM42: 2/3 s
-Drop outtime on running flame failure: < 1 s
The times given on the burner control label correspond to
the values guaranteed. The actual values differslightly
from the values given,pre-purge and waiting times are in
fact longer and safety time shorter than their nominal
values.
4007_r00
1/4

VM41 VM42
Power consumption,at starting up: 12 VA 15VA
Power consumption,running: 9 VA 12VA
Contact rating: I max
-Thermostat: 6 A cosϕ> 0.4
-EV1: 0.5 A cosϕ> 0.4
-EV2: 0.5 A cosϕ> 0.4
-Burner motor: 3 A cosϕ> 0.4
-Alarm: 1 A cosϕ= 1
-Ignition transformer: 2 A cosϕ> 0.4
Fuse rating internal: 6.3 A T
Fuse rating external: 5 A F
Flame control:
The ionization flame detecting device makes use of the
rectification property of the flame.
The ionization flame detecting device is not asafe-to-touch
output(no provision with protective impedance).
- Minimum ionization current: 1.2µA
on request: 0.5µA
- Recommended ionization current:
≥10 times the minimum ionization current
- Minimum insulation resistance of cable and detection
electrode to earth: ≥50MΩ
- Max. parasitic capacitance ofdetection electrode:
≤1nF
- Max. short circuitcurrent: < 200µA AC
Weight including socket: 250g
CONSTRUCTION
Aspecial building technique and the surface mounting
technology for the electronic components have allowed to
realize aboxstructure and to maintain the dimensions of
the previous mechanical controls unchanged.
The enclosureprotectsthe control from mechanical
damage, dustand dirtfrom the conditions of installation.
Avaristor protects the control from voltage transients on
the mains supply.
Afuse protects the internal relay of the control boxin case
of short circuits on the outputs(gas valves, motor,
transformer and lock-outsignal). This is not an accessible
fuse and the control must be protected with afuse of the
fast blowtype suitable tothe loads connected and never
exceeding 5A.
OVERALL DIMENSIONS
Fig. 1 shows the control overall dimensions.
Fig.1
ACCESSORIES
The controls are supplied with inbuilt resetbutton; the
enclosures arearranged for the fitting of strain relieves
and/or cable holders on the sides (see fig.2).
Fig.2
WIRING
The lenght ofthe cables of external components should not
be longer than 1 m.
For the wiring of the controls you can use connecting
sockets of our production.
Socket N is suitable for the VM41 control, socket NE is
suitable for the VM42 control.
Fig.3 shows these accessories and all relevant dimensions,
useful forthe installation.
Socket N
Socket NE
Fig.3
Socket N
Socket NE
2/4 4007_r00

Regarding the connection of the control units, provisions
such as strain reliefs, sufficient earth terminals and neutral
terminals should be present in the appliance or in external
connection boxes.
DIRECTIONS FOR THE INSTALLATION
− For technical-safety reasons aregulation shutdown
must occur every 24 hours (systems for non-
permanentoperation).
− Automatic controls are safety devices and shall not be
opened. Responsibility and guarantee of the
manufacturer is invalidated if the control is opened.
− The control must be connected and disconnected only
with the supply disconnected.
− The control can be mounted in any position.
− Avoid exposure to dripping water.
− Ventilation with the lowest temperature ensures the
longest life of the control.
− Make sure that the type (code and times) you areusing
is correct before installing or replacing the control.
ELECTRICAL INSTALLATION
− The national and European applicable standards
(e.g.EN 60335/1prEN 50165) concerning electrical
safety must be respected.
− Live and neutral should be connected correctly, a
mistake could cause adangerous situation, i.e. the
control and valves would still be live with the
thermostats and limitsswitched off. Besides, if live-
neutral polarity is not respected the control locks out
after TS.
− Before starting check the cables carefully. Wrong
connections can damage the control and compromise
the safety.
− The earth terminal of the control, the metal frame of the
burner and the earth on the mains supply must be well
connected.
− Avoid putting the detection cable close to power or
ignition cables.
− Use aheat resistant cable and detection probe, well
insulated to ground and protected from possible
moisture (or water in general).
In case of live-neutral network with unearthed neutral or
live-live network (with centerof the star not earthed) the
control can operate correctly by means ofan inbuilt
resistor.
In the event of bad insulation between live(s) and earth the
voltage on the ionization probe can be reduced until it
causes the control to lock-out. In the presence of this kind
of network itis advisable to use ourtransformer type AR1
(booster).
CHECKING AT START
Always check the control before the first startand also
after amendmentsor along period of no operation of the
system.
Before any ignition attempt make surethat the combustion
chamber is free from gas.
Then make sure that:
− if the attempt to start occurs without gas supply the
control locks out after TS;
− when stopping the gas flow(while the control is in
operational state)supply to the gas valve is interrupted
within 1second and, after arecycling, the control
proceeds to lock-out (VM41);
− when stopping the gas flow(while the control is in
operational state) supply to the gas valves is interrupted
within 1second and the control proceeds to lock-out
(VM42);
− operating times and sequence are suitable;
− the level ofthe flame signal is sufficient, see Fig.3 to
execute the test;
− the intervention of limiters orsafety devices causes a
safety shut-down according tothe application.
Fig.4
OPERATION
When the thermostatsclose, the control gives the starting
command to the burner motor and checks the position of
the airpressureswitch contacts; only if the test is positive
with the air pressureswitch in “air flow”stateprepurge time
(TW)begins, at the end ofwhich the gas valve is energized
and the ignition device is operated, thus starting the safety
time (TS).
If aflame is detected during the safety time the ignition
device is inhibited.
On the contrary, ifthe control does not detect aflame by
the end of TS, itproceeds to non-volatile lock-out,the gas
valve, the ignition device and the burner motor are
switched off while the lock-out signal output is supplied.
Model VM42 controls the opening of asecond gas valve
15-20 seconds after the flame detection.
If aflame failureoccurs in the running position the gas
valves are switched offand the VM41 proceeds to a
repetition of the ignition cycle,while the VM42 proceeds to
non-volatile lock-out.
The following diagrams are useful to understand the
operations of the controls.
Abnormal operation
- Air flowfailure
VM41:
In case of failure of the air pressure switch or insufficient
air flowthe control proceeds to lock-out with adelay of
about 15 seconds (t1 delay).
VM42:
In case of failure of the air pressure switch or insufficient
air flowin the running position the control proceeds to
lock-out with adelay of about 3seconds. Air lack at start
causes a lock-out within about8 seconds (t1 delay).
CAUTION: If for any reason the burner system is not
equipped with air pressure switch, terminals n.4 - 6 - 7
mustbe short-circuited.
- Parasitic flame
VM41:
The presence of aflame signal at start or during pre-
purge time causes lock-out within about 15 seconds (t2
delay).
VM42:
The presence ofaflame signal atstart causes alock-out
within about 8seconds. Parasitic flame during pre-purge
causes a lock-out within about3 seconds (t2 delay).
RESET OF THE CONTROL
When the control has gone to lock-out awaiting time of 10
seconds should be allowed before attempting to reset the
control.
Control unit
8
Detection probe
4007_r00 3/4

BRAHMAS.p.A.
Via delPontiere, 31
37045 Legnago (VR)
Tel. [phone] - Telefax+39 0442 25683 03/03/26 Subject to amendments without notice
http://www.brahma.it
E-mail: [e-mail]
4/4 4007_r00