Bender RCMA421H - Transformer Monitoring; Quick Query of the Rated Residual Operating Current

Function
10
RCMA421H_D00069_00_M_XXEN/05.2014
The device will check the circuit for the presence of residual currents even dur-
ing the self test.
An external measuring current transformer (e.g. WN-35BS) is used for residual
current measurement. The actual measured value is indicated on the LCD. If
the rated residual operating current of 6 mA is exceeded, the alarm relay K2
will change to the alarm state and the TRP alarm LED will light up.
Once the alarm relay has switched, the residual current must fall to less than
the rated residual operating current.
If it does not, error code E.04 will appear on the display and the ERR alarm LED
will flash. This means that the connected contactor has not shut down the
faulty circuit.
If the residual current falls below the release value, the error will continue to
be signalled due to the permanently activated fault memory. The alarm relay
K2 will not switch back to the initial state and the TRP alarm LED will not go
out until the reset button R is pressed or the power supply voltage is interrupt-
ed.
Parameters are assigned to the device via the LCD and the control buttons on
the front panel; this function can be password-protected.
3.2.1 Transformer monitoring
The connections to the measuring current transformer are checked periodi-
cally every 10 s for short and open circuits. In the event of an error, the alarm
relay K2 will switch, the red TPD alarm LED will light up and the yellow ERR
alarm LED will flash (error codes E.01 or E.03). Once the error has been elimi-
nated, the alarm LEDs and the alarm relay will remain in the alarm state. Press-
ing the reset button R or sending a reset command via the RS-485 interface
will switch K2 back to its initial state and the alarm LEDs will go out.
3.2.2 Quick query of the rated residual operating current
When the display is in standard mode, the rated residual operating current I
Δn
= 6 mA can be queried by pressing the Up or Down button (< 1.5 s). Switching
to menu mode is not necessary. Quick query mode can be exited by pressing
Enter (< 1.5 s).