Herz firematic PELLET 120, Руководство по эксплуатации

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T-CONTROL 9
55
External requirement at digital input:
At a digital request the external set temperature gets transmitted as value to the heat supplier.
External requirement at analogue input:
At an analogue request a calculated (= linearly interpolated) temperature gets transmitted to the heat
supplier. The graph gets regulated by the parameters „analogue must temperature 4 mA“ and „analogue
must temperature 20 mA“.
For example at an analogue request with an current signal of 12 mA, a temperature of 60 °C is registered at
the heat supplier, provided that the digital requirement (= external must temperature) is not higher.
figure 9. 2: Analogue set temperature as a function of the applied current signal of the external
requirement
At the input of the external requirement module a current signal between 4 and 20 mA should be given,
because a current signal is compared to a voltage signal insensitive to electromagnetic disturbances and
voltage losses at the cables. With an internal resistor (500 Ohm) the current signal is converted into a
voltage signal.
Input signal of the external requirement module
External requirement
module
500 Ω
Input signal =
current signal
a
n
a
lo
g
u
e
m
u
s
t
te
m
p
e
ra
tu
re
[
°C]
current signal [mA]