User Manual

3UG4641 cos phi and active current monitoring relay
12.3 Functions
3UG4 / 3RR2 monitoring relays
Manual, 02/2013, NEB927043002000/RS-AA/002
281
12.3 Functions
General functionality
The 3UG4641 cos phi and active current monitoring relays are self-powered (measuring
voltage = rated control supply voltage) and monitor the power factor value in one phase (PF:
power factor) and the resulting active current I
res
(I resistive), for overshoot(φ▲ / I
res
▲),
undershoot (φ▼ / I
res
▼) or range monitoring (φ▲ and φ▼ / I
res
▲ and I
res
▼) depending on the
setting. The load to be monitored is connected upstream of the terminal IN. The load current
flows 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 find the setting ranges and factory settings of the available parameters in Chapter
"Operation (Page 285)."
You will find a descri
ption of the individual parameters in Chapter "
Parameters (Page 351)."
Note
The specified 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 off (I
res
▼ = off), 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 find more information in Catalog LV10
(www.siemens.com/lowvoltage/infomaterial
).
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.