GE GFK-2958E, User Manual

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Chapter 3: Configuration
GFK-2958E RSTi-EP User Manual 34
3.7 Calculation of Power Loss
The power loss of the network adapter is calculated als follows:
P
network adapter
= P
0
+ N * P
mod
+ I
in
* ΔU
in
+ I
out
* ΔU
out
P
0
Static power loss in the network adapter 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
Maximum power loss module
I
in
Current fed in through the input current path
ΔV
in
Voltage drop across the contacts in the input current path 0,18 V
I
out
Current fed in through the output current path
ΔV
out
Voltage drop across the contacts in the output current path 0,18 V
The power loss of a RSTi-EP station is calculated using the power loss of the network adapter and the
power loss of the individual 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 GE technical support or GlobalCare.
P
station
= P
network adapter
+ N * P
module
3.7.1 Calculation of Power Loss for Use in a Potentially Explosive
Atmosphere
The module specific data, needed to calculate the output power loss, are provided in the ATEX
certificate which you can download from the GE website.
3.8 Feedback Energy in DO Modules
With digital output modules, power is fed back through the channels when inductive loads are
switched off. The respective permissible breaking energy is noted in the technical data of the DO
modules. Depending on the switching frequency, the breaking energy leads to additional energy loss
in the output module.
If the maximum permissible feedback energy for a module is exceeded, the module shuts down
temporarily.
Note: Feedback energy can be prevented by installing external freewheeling protection. With it, the
same switching rate can be achieved with an inductive load as with a resistive load.