Siemens 3UG4 User Manual

Accessories
13.2 Accessories for 3UG4 monitoring relays
3UG4 / 3RR2 monitoring relays
Manual, 05/2016, NEB927043002000/RS-AC/004
341
13.2.5.4
Installation faults
For reasons of clarity, the representations show only the residual current transformer with
the currents passing through it rather than the complete residual current monitoring unit and
residual current transformer. If the vectorial sum of the currents passing through the residual
current transformer does not equal zero, part of the current is bypassing the transformer to
ground and the residual current monitoring relay triggers a warning or an alarm if the current
is correspondingly high.
In some instances, false alarms may occur for no apparent reason. However, these
represent installation faults.
The following examples demonstrate the most common installation faults.
Parallel connections of conductors
If several residual current monitoring relays are installed in one network, a conductor routed
through several residual current transformers must not be connected to itself downstream of
the transformer, as this would effectively represent a parallel connection of the conductor.
This fault occurs particularly often with neutral conductors. This fault causes the currents to
be distributed across the conductor. This means that the current flowing through the load to
be monitored is no longer 100 % of the total current and all integrated monitoring relays
measure fault currents.

Siemens 3UG4 Specifications

General

Type of voltage	AC/DC
Number of CO contacts for auxiliary contacts	1
Number of NC contacts delayed	0
Number of NO contacts delayed	0
Number of change-over switches delayed	0
Number of NC contacts undelayed	0
Number of NO contacts undelayed	0
Number of change-over switches undelayed	1
Width	22.5 mm
Housing Width	22.5 mm
Operating Temperature	-25 ... 60 °C
Protection Class	IP20
Design of the product	Monitoring relay
Type	Monitoring relay
Operating frequency rated value	50 ... 60 Hz
Rated Operational Current	0.1 ... 10 A
Adjustable response value current	0.1 ... 10 A
Contact Configuration	1 CO contact
Operating range factor control supply voltage rated value at AC	0.8-1.1 x Un
Operating range factor control supply voltage rated value at DC	0.8-1.1 x Un