Siemens SIRIUS 3UG4 - Page 84

All 3UG4511 line monitoring relays feature at least one output relay (output relay K1 CO
contact). The 3UG4511-.B line monitoring relays have an additional relay (output relay K2 CO
contact). Output relay K2 switches synchronously with output relay K1.
No settings are required for operation.
Note
The speci󹪝ed voltages represent the absolute thresholds.
Monitoring
If the correct phase sequences are applied to terminals L1‑L2‑L3, the output relay picks up after
the response time and the "contact symbol" LED lights up green. If the phase sequence is
incorrect, the output relay remains in its quiescent position. After the power system has been
disconnected, the output relays drop out after the response time has expired.
Note
After failure of one phase, motors generate a reverse voltage at the terminal of the failed phase
due to the regenerative power recovery. This can be up to 90 % of the line voltage in magnitude.
Because the 3UG4511 line monitoring relays are not protected against reverse voltage, such a
phase failure is not reliabily detected.
If this type of monitoring is required, the 3UG4512 line monitoring relay should be used, for
example!
You will 󹪝nd the switching states of the output relays below in section "Function diagrams" and
in Chapter "Diagnostics (Page 85)."
Reset response
The device features an autoreset that resets the output relay to its original state after an error
message and recti󹪝cation of the fault that has occurred.
Function diagrams 3UG4511
Correct phase sequence Incorrect phase sequence
11/14
L1-L2-L3
11/12
21/24
21/22
ON
11/14
L3-L2-L1
11/12
21/24
21/22
OFF
3UG4.1 line monitoring relay
6.2 3UG4511 line monitoring relay
SIRIUS 3UG4 / 3RR2 monitoring relay
84 Equipment Manual, 07/2021, NEB927043002000/RS-AD/005