11.3 Functions
General functionality
The 3UG4641 cos phi and active current monitoring relays are self-powered (measuring
voltage = rated control supply voltage) and monitor the cos phi value (PF: power factor) and the
resulting active current I
res
(I resistive), depending on the setting, for overshoot (φ▲ / I
res
▲),
undershoot (φ▼ / I
res
▼) or in range monitoring (φ▲ and φ▼ / I
res
▲ and I
res
▼). The load to be
monitored is connected upstream of the terminal IN. The load current ows through
terminals IN and Ly / N. The devices are powered with a voltage of 90 to 690 V through the
terminals Lx and Ly / N .
The 3UG4641 cos phi and active current monitoring relays have a display and are parameterized
with three keys.
You will nd the adjustment ranges and factory settings of the available parameters in Chapter
"Operation (Page 223)".
You can nd a description of the individual parameters in Chapter "Parameters (Page 281)".
Note
The specied voltages represent the absolute thresholds.
Monitoring
If the motor is switched on and the current value overshoots the measuring range limit 0.2 A, 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.
If monitoring for active current undershoot is switched o (I
res
▼ = o), and if the load current
undershoots the lower measuring range threshold (0.2 A), the change-over contacts remain
unchanged. If a threshold is set for monitoring for active current undershoot, undershoot of the
measuring range threshold (0.2 A) will result in a relay response of the change-over contacts.
Note
In the case of active currents I
res
> 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).
Startup delay
To be able to start a drive, the output relay switches to the correct state during the ON-delay time
(onDel) depending on the selected open-circuit principle or closed-circuit principle, even if the
measured value is still under the set value.
Tripping delay
If the measured value overshoots or undershoots the set threshold after expiry of the ON-delay
time (onDel), the set tripping delay time (Del) and the relay symbol will ash. After expiry of this
3UG4641 cos phi and active current monitoring relay
11.3 Functions
SIRIUS 3UG4 / 3RR2 monitoring relay
Equipment Manual, 07/2021, NEB927043002000/RS-AD/005 219
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