Siemens 3UG4 User Manual page 371

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.
● Inflow control (UN ≙ NC) (on 3UG4501 only)
When the rotary button is in the UN (Undershoot) position, the monitoring mode inflow
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
3UG4 / 3RR2 monitoring relays
Manual, 05/2016, NEB927043002000/RS-AC/004
Parameters
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