FMS Commissioning
Run to shut-off limits
Run to shut-off limits
As each monitoring system the FMS has tolerances, which affect the
adjustment precision. With the FMS these tolerances can be affected by
parameter settings.
If the firing system is adjusted, it has to be ensured that also the flame burns
reliably and stably in consideration of these tolerances. In order to prove this it
is necessary not only to prove the compound settings to the adjusted
setpoint, but to the so-called shut-off limits, i.e. with the actuator values, that
the FMS can take due to the permissible tolerances without shutting off just
yet.
This inspection has to be performed for the whole load range and for every
operating mode. This inspection can be abandoned if:
!
the system is equiped with a failure-safe O - or CO-control, which causes
2
the shut-off of the burner due to an uncomplete combustion.
or
!
the system is equipped wiht a failure-safe O / CO- regulation, which
2
compensates the tolerances of the combustion.
or
!
it is guaranteed that the relevant operating mode gets as much excess air
over the full range, that the tolerances of the FMS do not have any effect.
or
!
the parameters of the FMS are set that way, that the tolerances to air
deficiency are 0 digits, i.e. there are existing only tolerances to excess air.
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If You abandon the inspection of the shut-off limits due to one of these
measures, You have to check the effectiveness of this measures, i.e. the
O / CO- regulation respectively O / CO- control the stability of the
2 2
combustion at the adjusted shut-off limits value are to be checked.
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Due to the evidence of conformity to public and inspection authoroties and
quality management , liability reasons etc. we would therefore strongly
recommend that You always document the run to shut-off limits. You will find
an example protocol in the appendix page 158.
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Repeate this methode for all relevant operating modes (curve sets). As the
case may be the above described inspection has to be executed in direction
excess air instead of direction air deficiency if You cannot ensure that with
the adjusted limits direction excess air, the flame burns reliably and stably and
no CO arises from excess air.
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Checking the shut-off limits
Selector switch (1) to "Load rating”
at three-point step output
Run to load point to be checked
Wait until the system has run to that point
Mode selector switch (2) to "Setting”
Adjust set-point value (4) of the three-point step channel in
the air deficiency direction (for dead band setting, see parameters 62-76)
Check combustion
Reset set-point value (4) to original value
In this way run all channels in succession to the limit at the
various load points -normally at low, medium and full load
67
i
!
!
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