SMY133-SMY134-SMP133 Operating Manual
If the
4-20mA
RCT type is set, residual current value is marked as possible wrong and the
indicator flashes at the display upper right corner as soon as the RCT secondary current
drops below 3.8 mA, indicating wrong connection or possible damaged RCT .
As soon a residual current input is used as analog input (AI) and corresponding action is
defined in the I/O block setup (see below), residual current monitoring on appropriate input is
suppressed and appropriate I
Δ
value is no longer available!
5.4 Tips & Hints
•
Never lead the PE conductor through a RCT, only
all live conductors
can be threaded
through. The only exception is when residual current is monitored by a single PE conductor
measurement – then it must be
the only conductor
threaded through.
•
Never lead a shielded cable through the RCT.
•
Install the RCT on straight part of a cable, far enough from bends. Center the cable inside the
RCT window as precise as possible. Otherwise, false residual currents may appear.
•
To reach higher immunity to false residual currents due to asymmetric installation, especially
when low residual currents to by measured, use a RCT with a larger window diameter than is
necessary.
•
Take in account native leakage currents caused by long cables (stray capacitance),
capacitive filters, surge arresters, etc., especially when many single-phase appliances
connected to the PE-conductor (for safety or other purposes) installed in the monitored
network. They can cause nuisance residual current indication.
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