CIB UNIGAS IDEA NG280 Manual Of Installation - Use - Maintenance Download

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SIEMENS LME11/21/22 CONTROL BOX

The series of equipment LME.. is used for the starup and supervisione of
1- or 2- stage gas burners. The series LME.. is interchangeable with the
series LGB.. and LMG.., all diagrams and accessories are interchangea-
ble.

Comparative table

Preconditions for burner startup

Burner control must be reset

All contacts in the line are closed, request for heat

No undervoltage

Air pressure switch LP must be in its “no-load” position

Fan motor or AGK25 is closed

Flame detector is darkened and there is no extraneous light

Undervoltage

Safety shutdown from the operating position takes place should mains
voltage drop below about AC 175 V (at UN = AC 230 V)
Restart is initiated when mains voltage exceeds about AC 185 V (at UN =
AC 230 V).

Controlled intermittent operation

After no more than 24 hours of continuous operation, the burner control
will initiate automatic controlled shutdown followed by a restart.

Reversed polarity protection with ionization

If the connections of live conductor (terminal 12) and neutral conductor
(terminal 2) aremixed up, the burner control will initiate lockout at the end
of the safety time “TSA”.

Control sequence in the event of fault

If lockout occurs, the outputs for the fuel valves, the burner motor and the
ignition equipment will immediately be deactivated (< 1 second).

Operational status indication

In normal operation, the different operating states are showed by means
of the multicolor LED, inside the lockout reset button:

During startup, status indication takes place according to the table:

START-UP PROGRAM

As far as the startup program, see its time diagram:

Start command (switching on)

This command is triggered by control thermostat / pressure controller
«R». Terminal 12 receives voltage and the programming mechanism
starts running. On completion of waiting time «tw» with the LME21..., or
after air damper «SA» has reached the nominal load position (on comple-
tion of «t11») with the LME22..., fan motor «M» will be started.

Waiting time

During the waiting time, air pressure monitor «LP» and flame relay «FR»
are tested for correct contact positions.

t11

Programmed opening time for actuator «SA»

(Only with LME22...) The air damper opens until the nominal load position
is reached. Only then will fan motor «M» be switched on.

t10

Specified time for air pressure signal

On completion of this period of time, the set air pressure must have built
up, or else lockout will occur.

Prepurge time

Purging the combustion chamber and the secondary heating surfaces:
required with low-fire air volumes when using the LME21... and with nomi-
nal load air volumes when using the LME22.... The diagrams show the so-
called prepurge time «t1» during which air pressure monitor «LP» must
indicate that the required air pressure is available. The effective prepurge
time «t1» comprises interval end «tw» through «t3».

t12 Programmed closing time for actuator «SA»

(Only with LME22...)During «t12», the air damper travels to the low-fire
position.

t3 Preignition time

During «t3» and up to the end of «TSA», flame relay «FR» is forced to
close. On completion of «t3», the release of fuel is triggered at terminal 4.

TSA Ignition safety time

On completion of «TSA», a flame signal must be present at terminal 1.
That flame signal must be continuously available until shutdown occurs,
or else flame relay «FR» will be deenergized, resulting in lockout.

t4 Interval BV1 and BV2-LR

Time between the end of TSA and the signal to the second fuel valve BV2
or to the load controller LR

B - B'

Interval for flame establishment

Burner operation position

C - D

Burner operation (heat production)

Controlled by "R" shutdown

The burner stops and the control device is ready for a new startup.

LGB Series

LMG Series

LME Series