User Manual

3UG4624 residual current monitoring relay
8.3 Functions
3UG4 / 3RR2 monitoring relays
Manual, 02/2013, NEB927043002000/RS-AA/002
173
8.3 Functions
General functionality
The 3UG4624 fault current monitoring relays are powered with a rated control supply voltage
of 90 to 690 V AC (rms value), 50 / 60 Hz through terminals Lx and Ly / N.
The 3UG4624 residual 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 177)."
You will find a description of the individual parameters in Chapter "
Parameters (Page 351)."
The main conductors and, if present, the neutral conductor to which the load is conne
cted,
are routed through the opening of the toroidal strip-wound core of a summation current
transformer. A secondary winding is placed arount this toroidal strip-wound core to which the
3UG4624 residual current monitoring relay is connected.
During fault-free operation of a plant, the sum of inflowing and outflowing currents is equal to
zero. No current is then induced in the secondary winding of the summation current
transformer.
When an insulation error occurs, for example, the sum of the inflowing currents is greater
than the sum of the outflowing currents.
The residual current induces a secondary current in the secondary winding of the
transformer. This current is evaluated in the monitoring relay and used to display the current
residual current and to switch the output relays when the set warning threshold or the
tripping threshold is overshot.
Note
The specified voltages represent the absolute thresholds.