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General Information
FMS Operating Principle
The internal load is the load value at which the compound currently stands.
It therefore corresponds indirectly to the output of the burner.
The internal load is displayed in addition to the external load signal.
In the "load value” position therefore both the external load (left-hand) and
the internal load (right-hand) are displayed.
The value of the internal load can be outputted via the monitor output, in
order to connect further units (e.g. O control, only on FMS 4). When
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connecting other units, it must be remembered that the signal in itself is
not error-proof.
When switching over to "Load value” with the burner running the burner
load can be set via the FMS. The load value can then be adjusted with the
channel 1 toggle switch.
The system follows this load value in the compound.
Operating a switch other than channel 1 causes the unit to exit manual
mode again.
The person commissioning the unit can adjust various functions of the
FMS
by way of parameters (e.g. post-ventilation time). The parameters are
classified into various safety levels. With the exception of the lowest safety
level these are accessible only with a password. The parameterisation can
be undertaken both on the unit itself and by means of a PC and Windows
software.
The FMS has 2 correction inputs. An analog signal (0/4 … 20 mA) can be
connected to these for shifting the set curves (e.g. for O correction or air
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temperature correction). The assignment of the correction to the individual
output channels and the mode of operation can be adjusted via
parameters.
If the FMS cannot perform a correction because a control element stop has
been reached, it adjusts the internal load and hence the compound until
the correction can take effect as required.
An output for controlling the speed of a combustion air fan or a
re-circulation fan etc. can be monitored by switching the pulse output of a
Namur transmitter directly to the FMS.
Continuous outputs and three-point step outputs have different feedback
requirements. In the case of continuous outputs comparisons are made
between output and feedback values in or to check the plausibility. The
units therefore do not have to be intrinsically error-free in order to form the
feedback signal. For availability reasons (minimisation of interference) the
reproducibility of the values should be as good as possible.
For technical reasons this method cannot be used in the case of
three-point step outputs. For this reason TÜV approved potentiometers
must be connected directly as feedback to the FMS. These
potentiometers must positively render the position of the damper.
Normally during pre-ventilation each control element runs as far as ist
uppermost stop. Now, by means of parameters, a limit can be set for each
channel that is not exceeded during pre-ventilation.
Internal load
Manual operation
Parameterisation
Correction
Facility for direct connection
of Namur transmitter
(option)
Freedom from error
of feedback signals
Pre-ventilation limit
