SMY133-SMY134-SMP133 Operating Manual
Residual currents are marked IΔ and can be checked on the instrument display. When any of the
RCM inputs is overloaded, the indicator flashes at the display upper right corner.
Then set the
CT
RCM
–ratio in the
Installation Setting
group of parameters.
The RCM inputs are insulated neither from instrument internal circuitry nor mutually! The
terminals IΔ12 and IΔ22 are connected internally, do not connect signals of different potential
to them!
One of outputs of each RCT can be optionally grounded to PE – in such case, always ground
the output connected to the
IΔ12
/
IΔ22
terminal(s)!
Take such grounding in account when one of residual current inputs is used for the RCM and
simultaneously the other one for a 20 mA DC current loop measurement or when a
temperature input is connected too to avoid possible short-circuits!
Maximum length of cable is 3 meters ! Otherwise, EMC-immunity of the instrument can be
degraded.
5.3 RCM Setup & Presentation
If a standard RCT with AC-current output is used, set its
CT
RCM
-ratio
in
the Installation
group of
parameters. Optionally, you can use the
I
RCM
-multiplier
too.
If a RCT with DC-current output loop 4/20 mA or 0/20 mA is used, switch appropriately the
RCT type
first by editing the
I
RCM
-multiplier
. Then enter the RCT primary current corresponding to 20 mA DC
output (in milliamperes – on the example above conversion ratio of 300 mA / 20 mA is set). The value
corresponding to 0 or 4 mA cannot be set – it is supposed zero automatically.
Effective values only of residual currents are available. The residual currents are marked as
IΔ1
and
IΔ2
.
The residual current values can be not only monitored and archived, but exceeding a preset level can
be signalled using appropriate I/O Setup condition – see appropriate chapter below.
If the
0-20mA
or the
4-20mA
RCT type is set, residual current value is marked as
overloaded and the indicator flashes at the display upper right corner as soon as the
primary residual current exceeds the value corresponding to secondary current of 20 mA,
indicating possible overload of the RCT.
37
Fig. 5.1 : Standard RCT
CT
RCM
–Ratio and
I
RCM
-
Multiplier Setting
Fig. 5.2 : DC-Current
Output RCT Ratio Setting
