JUMO 709051, Руководство по эксплуатации, Страница: 72 / 92

6 Special device functions
72 V1.00/EN/00741192/2021-03-30 [IPC 300]
6.8 External current sensors
6.8.1 Load monitoring
The load monitoring with power reduction serves to protect the components/
system. If, during operation with 3 load strands, a load failure occurs, the cur-
rent that would have flowed in this strand is additionally distributed to the two
remaining load strands (Kirchhoff's law) and could therefore damage or even
destroy the heating elements used there (in the event of excess current).
The IPC 300 has an internal current sensor that measures the overall load cur-
rent. It is also possible to connect up to two external current sensors in order
to monitor individual load strands. In order to keep the designations for the
current sensors the same, however, all current sensors shall be designated ex-
ternal current sensors in the following. External current sensor 1 is installed in-
side the device and measures the overall load current. External current sen-
sors 2 and 3 are installed outside the IPC 300 and have three different config-
uration options:
- Error current
- Load current
- Mains current
To monitor the load, the individual strand currents must be measured using the
external current sensors (1 to 3). For this, at least one external current sensor
is necessary as a load current sensor. External current sensors 2 and 3 can be
configured with the measurand load current in the configuration level for this
purpose.
The load current in the figure corresponds to the overall load current and ap-
pears in the overview of the measured values under load current. The value for
ext. current input 1 is calculated by subtracting the strand currents of the ext.
current sensors from the overall load current:
Ext. current input 1 = overall load current - sum ext. current inputs 2 and 3
Ext. current input 1 = 150 A -50 A -50 A = 50 A
The current distribution is symmetrical due to equal loads.
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