Endress+Hauser nivocompact FTC 831, Installation And Operating Manual

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Connecting the Nivocompact with Electronic Insert EC 40
for AC (Two-Wire Connection)
Connecting in Series to a Load The level limit switch Nivocompact with electronic insert EC 40 must be
- like all switches - connected in series with the load (e.g. relays,
microcontactors, lamps) to the power supply.
Direct connection to the power supply without any intermediate load
connected (short-circuit!) will result in immediate and permanent damage to
the electronic insert.
The load can be connected to Terminal 1 or 2 of the electronic insert.
It is unimportant whether L1 is connected to Terminal 1 or 2.
Power Voltage The voltage across Terminal 1 and 2 of the electronic insert must be
correspondingly higher to compensate for the voltage drop across the
connected load.
Load Cut off Note that loads connected in series are not completely disconnected from
the power supply if the electronic switch in the electronic insert of the
Nivocompact »disconnects« (blocks) with level alarm.
Because of the current requirements of the electronics, a small »no-load
current« still flows through the connected load.
When the load is a relay with a very small retaining current, it is possible
that the relay does not de-energise. In this case connect an additional load
in parallel to the relay, e.g. a resistor or signal lamp.
Fig. 10
Connecting the Nivocompact FTC 831
with electronic insert EC 40
U
1-2
∼
: 21 V...250 V across Terminals 1 and 2
of the EC 40
R: Connected (external) load, e.g. relay
F: Fine-wire fuse, load-dependent
U
R
: Voltage drop across the load
and the fine-wire fuse
M: Ground connection to silo or
metal parts near to the silo
E: Grounding
Nivocompact FTC 831 Connection
14