Relay switching behavior
An output relay responds in accordance with the set switching behavior. Several variations can
be distinguished here:
• Closed-circuit principle (NC)
If the closed-circuit principle is selected, the output relay picks up when the voltage is applied
(contact .1/.4 closed). The output relay drops out in the event of a fault (contact .1/.2 closed).
If the supply voltage fails, the output relay also returns to this position so that a supply voltage
failure is detected and reported.
The semiconductor output responds as an NC contact, in other words, if a fault is detected,
the output Q has a high resistance.
• Open-circuit principle (NO)
If the open-circuit principle is selected, the output relay only picks up in the event of a fault
(contact .1/.4 closed). Interruptions to the supply voltage or the rated control supply voltage
are not displayed.
The semiconductor output responds as an NO contact, in other words, if a fault is detected,
the supply voltage is present at output Q.
• Drainage control (OV ≙ NO) (on 3UG4501 only)
If the rotary button is in the OV (Overshoot) position, monitoring mode drainage control is
selected. On the drainage control, contacts 11/14 are closed when the upper threshold is
overshot after the tripping delay time has expired. Contacts 11/12 are only closed when the
lower threshold is undershot.
• Inow control (UN ≙ NC) (on 3UG4501 only)
When the rotary button is in the UN (Undershoot) position, the monitoring mode inow
control is selected and the output relay picks up when the supply voltage is applied
(contact .1 / .4 closed). When the upper threshold is overshot, the output relay drops out
(contact .1/.2 closed). When the lower threshold is undershot, the output relay picks up again
(contact .1/.4 closed).
Unlike with pure reconnection at the CO contact output, with use of the relay switching behavior
parameter, it is possible to prevent unwanted pumping in the absence of a supply voltage.
Possible indications on the display:
• Closed-circuit principle: NC
• Open-circuit principle: NO
Sensor sensitivity
The sensor sensitivity is the sensitivity R sens, with which the lling level monitoring relay must
respond.
The working principle of the lling level monitoring relays is based on resistance measurement
of conductive liquids (conductive measurement method). This method can be used with all
liquids and substances that have a resistivity < 200 kΩ.
Table B-1 Resistivity of liquids
Product kΩ Product kΩ
Buttermilk 1 Natural water 5
Fruit juice 1 Waste water treatment 5
Parameters
SIRIUS 3UG4 / 3RR2 monitoring relay
288 Equipment Manual, 07/2021, NEB927043002000/RS-AD/005
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