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1MRS750881-MUM
5.3.4.
Remote Monitoring and Control Unit
Technical Reference Manual
When sensitive earth-fault protection is needed, core balance
transformers are not recommended to be replaced with the
numerically derived sum of phase currents. Normally, an earth-fault
setting below 10% of the rated value requires the use of a core
balance transformer.
Table 5.3.3-1
Virtual analogue channels
Virtual channel
Numeric derivation
I
= -(I
0s
b
I
= -(I
0bs
U
= (U
0s
= (U
b
U
0bs
b
= (U
U
12s
= (U
b
U
23s
= (U
b
U
31s
= (U
b
U
12bs
= (U
b
U
23bs
= (U
b
U
31bs
a.
A minus in front of the parenthesis means, that the default direction of neutral current is
assumed to be from the line to the busbar, while the normal power flow is from the
busbar to the line.
b. This virtual channel is supported in REC 523 revision F or later.
Temperature measurement
The temperature measurement is calibrated to measure the ambient temperature of
the REC 523 device mounted in an enclosure. Furthermore, the temperature
information is used to control the charging voltage of the batteries.
The measured ambient temperature values can be forwarded to the control centre.
The dead band of the temperature change report is defined by the temperature delta
parameter of the PSC board.
Heating is needed if the REC 523 device is installed in a separate enclosure
outdoors, where the ambient temperature may fall below -10...0°C. Heating is also
required when the environment is very damp and dehumidifying is needed. The
parameter Heat limit is used for selecting the limit value for the heater in the
range of
-25°...+15°C. At lower values the cabinet heating is switched on and at upper values
switched off. The hysteresis of heating is stable within 4°C. Indication of the heater
status in REC 523 configuration is as follows:
• REC 523: PSC_7_HeatStat
The power supply and charger unit (PSC) has one output, PSC_7_SO1, which can
be parametrized as a heater output. After this, the output is no more controllable
from the application. The relay output is closed when the temperature falls below the
a
+ I
+ I
)
L1
L2
L1
a
+ I
+ I
)
L1b
L2b
L1b
+ U
+ U
)/3
1
2
3
+ U
+ U
)/3
1b
2b
3b
- U
)
1
2
- U
)
2
3
- U
)
3
1
- U
)
1b
2b
- U
)
2b
3b
- U
)
3b
1b
REC 523
Priority number
1
2
3
4
5
6
7
8
9
10
33
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