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8 Internal Burner Firing Rate Controller
8.7 Input Signals
The analogue inputs can be preset in various forms.
Actual value:
• as 0/4-20 mA current signal, terminals 4 and 5 (+), 3 (-)
• as non active current signal 4...20 mA (two-wire connection), terminal 23, + 24V supply,
terminals 4 and 5 input
• as 0...10 V voltage signal
• as 0...5 k resistance signal, terminal 4, 5 and 6
• directly as PT 100 terminal 21, 20, 19 as three-wire connection (0 – 320 °C)
Outside temperature (setpoint-shifting) - only available if ETAMATIC OEM has the option "con-
trol by atmospheric condition"
• as PT100 (0 – 320 °C) as three-wire connection, terminals 39, 40, 41 (default)
• as 4...20mA current signal, terminals 39 (-) and 40 (+),
special option, please order separately
• as non active current signal 4...20 mA, term. 23 + 24V supply, terminal 40 input
8.8 Operating Description
The burner start-up is carried out as described above. At least ’Burner ON’ signal and ’Re-
lease’ must be sent by firing rate controller.
The burner starts as soon as it is receiving signals ’Burner ON’ and ’Release’ from firing rate
controller. The firing rate controller is in operation not before the burner is running and the sig-
nal ’Control Release’ is pending.
The default value of firing rate for fuel/air ratio control is set via integral firing rate controller.
Depending on the difference between actual and setpoint value and adjusted control param-
eters this default firing rate value is set. When actual value is exceeding to maximum value
the firing rate controller switches OFF combustion.
The firing rate controller is active in AUTOMATIC mode only.
8.9 Steam Pressure
If you get a steam-pressure signal from a pressure transmitter on terminal 3, 4 and 5, you must
short-circuit the PT100 input at terminal 20 and 21.
8.10 Control by Atmospheric Condition
If the burner firing rate controller is configured as "controlled by atmospheric conditions" the
setpoint value can be shifted between the parameterised setpoint minimum and setpoint max-
imum by connecting another PT 100 temperature sensor. When utilising control by atmos-
pheric conditions, the outside temperature is a component of setpoint calculation. This allows
the operator to enter a minimum and a maximum setpoint, between which the outside temper-
ature can determine the final setpoint value.
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