Siemens 3UG4 - Installation Specifications

Accessories
13.2 Accessories for 3UG4 monitoring relays
3UG4 / 3RR2 monitoring relays
Manual, 05/2016, NEB927043002000/RS-AC/004
335
13.2.5.2
Installation specifications
Note
Please ensure strict adherence to the installation specifications for live cables.
WARNING
Open-circuit voltage may result in death, serious injury or material damage
The current transformer output is a constant current power supply. In accordance with
U = R * I, the output voltage increases with an increasing resistance. If the connecting
terminals of the current transformer are open, the output voltage may become high enough
for you to put your life at risk or permanently damage the current transformer.
Avoid operating the unit when open. Operating a network for monitoring safely and without
faults requires that the monitoring relay and the 3UL23 residual current transformer have
been installed completely. It is absolutely necessary to short-circuit previously installed
3UL23 residual current transformers when the units are not connected to a monitoring
relay.
3UL23 residual current transformer conductor cross-sections
In accordance with DIN EN 60204-1 "Safety of machinery", the current carrying capacity of
conductors is limited depending on their cross-section. This results in the ideally suitable
residual current transformer to be used as per the following table. Please observe potentially
deviating, local installation specifications.
Order number
Bushing opening
Diameter [mm]
Max. conductor cross-section
3P copper cable + N [mm
2
]
AWG [kcmil]
Rated current per phase [A]
3UL2302-1A 35 25 4 85
3UL2303-1A
55
50
1 / 0
150
3UL2304-1A
80
150
300
225
3UL2305-1A
110
240
500
400
3UL2306-1A
140
2 x 185
2 x 350/400
500
3UL2307-1A
210
2 x 240
2 x 500
630
3UL23 residual current transformers for external fault current monitoring