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Building Technologies Basic documentation LMV37.4... CC1P7546en
HVAC Products 8 Connection to load controllers 01.12.2009
8.6 External load controller via analog input X64.1
/ X64.2
For the preselection of external outputs, an analog 4…20 mA input is provided.
Burner startup can take place only when contact X5-03/1 is closed (load controller (LR)
On / Off).
A disruption of the current input or a current signal <3mA leads to deactivation of the
analog input’s external preselected output. To avoid unnecessary positioning steps of
the actuators when the input signal varies, it is possible to set a minimum positioning
step for the predefined output. The minimum positioning step only becomes active in
modulating operation. For the external load controller via the analog input, a value of 1%
is preset.
No. Parameter
123.1 Minimum output positioning step: Output external load controller analog
X64
GND
PWM fan
LMV...
Bild 364e /04 09
5
4
3
2
1
Figure 37: External load controller via analog input X64.1 / X64.2
8.6.1 Thresholds for modulating operation
Actual value Current Display / output value
Low-fire 3...4mA 20%
Low-fire 4mA 20%
High-fire 20mA 100%
8.6.2 Switching thresholds for 2-stage operation
For multistage operation a hysteresis band is realized to thresholds. The hysteresis
band replaces the minimum control step for multistage operation. The bandwidth is
approx. 1 mA.
2-stage operation
Actual value Current Display / output value
Stage 1 5mA (3...12mA) P1
Hysteresis band 12...13mA ---
Stage 2 15mA (13...20mA) P2
3-stage operation
Actual value Current Display / output value
Stage 1 5mA (3...7mA) P1
Hysteresis band 1 7...8mA ---
Stage 2 10mA (8...12mA) P2
Hysteresis band 2 12...13mA ---
Stage 3 15mA (13...20mA) P3
Switching thresholds /
minimum positioning
step
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