
3UG4.1 line monitoring relay
6.4 3UG4513 line monitoring relay
3UG4 / 3RR2 monitoring relays
122
Manual, 05/2016, NEB927043002000/RS-AC/004
6.4.2
Function
General functionality
The 3UG4513 line monitoring relays monitor for phase sequence, phase failure of one of the
three phases, and undershoot of at least one line-to-line voltage of the set nominal line
voltage by 20 % in a three-phase system.
The devices are self-powered (measuring voltage = rated control supply voltage) and work
on the closed-circuit principle. The 3UG4513 line monitoring relays monitor all phases of
three-phase AC networks from 160 to 690 V through terminals L1 / L2 / L3 and also draw
power from all three phases simultaneously.
The 3UG4513 line monitoring relay features two rotary buttons for setting the trip delay
(Delay) and the nominal line voltage (U
n
3AC).
The hysteresis is 5 % of the set value of the nominal line voltage.
The 3UG4513 line monitoring relays feature 2 output relays (output relay K1 and output relay
K2). The relays work synchronously.
Note
The specified voltages represent the absolute thresholds.
Monitoring
If the line voltage is switched on, the LED "coil symbol" will light up green. If the correct
phase sequence is applied to terminals L1-L2-L3 and if the monitored line-to-line voltage is
in the permissible range of the set nominal line voltage (U
n
3AC), the output relays pick up.
If the phase sequence is incorrect, the "phase failure / phase sequence" LED flashes red
and the output relays remain in their quiescent position.
If the monitored line-to-line voltage falls symmetrically (all three phase voltages at the same
time) or asymmetrically (only one phase voltage) to more than 20 % below the value for the
nominal line voltage set on the front of the device, after the time set on the front has elapsed
(Delay), the output relays will drop out and the "phase failure / phase sequence" LED will
light up red continuously. On a phase failure, the "phase failure / phase sequence" LED
lights up red continuously and the output relays drop out to protect the application from any
damage that may result. The set delay time has no effect on the phase failure monitoring.
Thanks to a special measuring method, a phase failure is detected with certainty despite
wide-range voltage from 160 to 690 V AC and reverse power of up to 80 % from the load in
the case of regenerative power recovery.
You will find the switching states of the output relays below in section "Function diagrams"
and in Chapter "Diagnostics (Page 125)."