Siemens SIRIUS 3UG4 User Manual

7.3 Functions
General functionality
Depending on the set threshold, the 3UG4621 / 3UG4622 current monitoring relays monitor a
single-phase AC load current (RMS value) or DC load current 󹪞owing over terminals IN and M of
the device for overshoot (I▲) or undershoot (I▼) or in range monitoring (I▲ and I▼). The
devices di󹪜er by their measuring ranges and versions with di󹪜erent rated control supply
voltages. The true root mean square value (tRMS) of the current is measured. Depending on
their design, the current monitoring relays are powered with a rated control supply voltage of
24 V AC/DC or 24 to 240 V AC/DC supply voltage through terminals A1/A2.
The 3UG4621 / 3UG4622 current monitoring relays have a display and are parameterized with
three keys.
You will 󹪝nd the setting ranges and factory settings of the available parameters in Chapter
"Operation (Page 127)."
You will 󹪝nd a description of the individual parameters in Chapter "Parameters (Page 281)."
Monitoring
If the rated control supply voltage is switched on and no load current is as yet 󹪞owing, the display
indicates 0.0 mA (on the 3UG4621) or 0.00 A (on the 3UG4622) and shows a symbol for current
overshoot monitoring, current undershoot monitoring, or range monitoring.
ON-delay time
If the load current overshoots the lower measuring range limit 3 mA (3UG4621) or 50 mA
(3UG4622), the set ON-delay time begins (onDel). During this time, undershooting or
overshooting of the set threshold values will not result in a relay response of the CO contact.
Tripping delay
If a threshold is reached, the output relay K1 responds after expiry of the tripping delay time
(
I D e l
▼
▼
) depending on the set relay switching behavior. An output change-over contact is
available as a signaling contact.
Note
For AC currents I > 10 A, commercially available current transformers, e.g. 4NC, can be used as
accessories. You will 󹪝nd more information in Catalog LV10 (https://
support.industry.siemens.com/cs/de/de/view/109482234/en).
Relay switching behavior
The relay switching behavior can be de󹪝ned in order to adapt the current monitoring relay to
di󹪜erent external circuit connections and applications.
If the closed-circuit principle (NC) is set, active switching of the relay when no fault is pending
also ensures that a power failure is detected as a fault. If the open-circuit principle (NO) is set,
active switching of the relay only when a fault occurs means that a power failure is not detected
as a fault.
3UG4621/3UG4622 current monitoring relays
7.3 Functions
SIRIUS 3UG4 / 3RR2 monitoring relay
Equipment Manual, 07/2021, NEB927043002000/RS-AD/005 123

Siemens SIRIUS 3UG4 Specifications

General

Brand	Siemens
Model	SIRIUS 3UG4
Category	Relays
Language	English