User Manual

System overview
3.3 Connection methods
3UG4 / 3RR2 monitoring relays
Manual, 02/2013, NEB927043002000/RS-AA/002
21
3.3.2 Spring-loaded connection
Spring-loaded connection
Without exception, all SIRIUS monitoring relays have spring-loaded connections. They make
wiring quick and maintenance-free, while also meeting high demands in terms of vibration
and shock resistance.
 
D
E

① Solid
② Finely stranded
③ Stranded
④ Finely stranded with end sleeve
a Spring-loaded terminal
b Busbar
Figure 3-1 Spring-loaded terminal
The conductors can be clamped directly or you can pre-treat them to add a form of splice
protection. This could involve attaching end sleeves or pin cable lugs to the ends of the
conductors; the tidiest solution is to use conductors whose ends have been sealed by means
of ultrasound.
The devices are equipped with a two-wire connection, i.e. two independent connections per
current path. Just one conductor is connected to each clamping point. The spring-loaded
terminal presses the conductor against the busbar, which curves around inside the terminal.
The high contact pressure per unit area achieved in this way is gas-tight. The spring-loaded
terminal presses flat against the conductor, but does not damage it. The spring force of the
spring-loaded terminal has been dimensioned such that the clamping force adjusts to the
conductor diameter automatically. This ensures that any conductor deformation caused by
settling, creepage, or yielding is compensated for. The clamping point cannot become loose
of its own accord. This connection is vibration- and shock-proof. Vibrations or shocks will not
damage the conductor, nor will they cause contact separation. These terminals are
particularly well suited for use with machines and systems which are subject to stresses
such as these, e.g. vibrators, rail vehicles, and elevators.
The contact pressure between the conductor and the busbar is set to an optimum level, so
this clamp connection is appropriate for high-voltage applications, as well as for transferring
voltages and currents in the mV or mA range within instrumentation and electronic
components.