Functions - Siemens SIRIUS 3UG4 Equipment 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 flowing over terminals IN and M of
the device for overshoot (I▲) or undershoot (I▼) or in range monitoring (I▲ and I▼). The
devices differ by their measuring ranges and versions with different 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 find the setting ranges and factory settings of the available parameters in Chapter
"Operation (Page 127)."
You will find 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 flowing, 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 el
▼
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 find more information in Catalog LV10
support.industry.siemens.com/cs/de/de/view/109482234/en).
Relay switching behavior
The relay switching behavior can be defined in order to adapt the current monitoring relay to
different 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.
SIRIUS 3UG4 / 3RR2 monitoring relay
Equipment Manual, 07/2021, NEB927043002000/RS-AD/005
) depending on the set relay switching behavior. An output change-over contact is
3UG4621/3UG4622 current monitoring relays
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7.3 Functions
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