User manual

Conguration| Calculation of power loss
26 1432790000/03/02.2014Manual u-remote
4.7 Calculation of power loss
The power loss of the eld bus coupler is calculated als fol-
lows:
P
coupler
=P
0
+N
*
P
mod
+ I
in
*
ΔU
in
+ I
out
*
ΔU
out
P
0
static power loss in the coupler 2,3 W
N number of modules
P
mod
power loss due to module supply from the system
current path
0,02 W
P
module
max. power loss module
I
in
current fed in through the input current path
ΔU
in
Voltage drop across the contacts in the input current
path
0,18 V
I
out
current fed in through the output current path
ΔU
out
voltage drop across the contacts in the output cur-
rent path
0,18 V
The power loss of a u-remote station is calculated using the
power loss of the coupler and the power loss of the individu-
al modules. It depends on the current in both current paths.
It is assumed that there is a maximum power loss of 2 watts
for the module
Maximum values were assumed for these calculations. If
you need detailed calculations, please contact Weidmüller
Service.
P
station
=P
koppler
+ N
*
P
module
4.8 FeedbackenergyinDOmodules
With digital output modules, power is fed back through the
channels during operation. The sum of the power fed back
through all channels is the output module’s feedback energy.
It varies with the ambient temperature.
If the maximum permissible feedback energy for a module is
exceeded, the module shuts down temporarily.
Feedback energy can be prevented by install-
ing external freewheeling protection. With it,
the same switching rate can be achieved with
an inductive load as with a resistive load.
Calculationoffeedbackenergy
The feedback energy for a digital output module can be cal-
culated as follows:
P = ∑
all channels
1/2 n
i
*
L
i
*
I
i
²
P Feedback energy of the module
n
i
Switching cycles of Channel i in 1/seconds
E
i
Feedback energy when shutting off Channel i during a shutdown procedure
I
i
Current through the load connected to Channel i
L
i
Inductance of the load connected to Channel i
Once the maximum permissible feedback energy E
max
is
reached, the module shuts down.
0,8
30 60
2,2
T [°C]
E
max
[W]
Themaximumfeedbackenergyvarieswiththeambienttemperature