Fault Signals - Siemens 8DJH Installation And Operating Instructions Manual

12 | Annex

12.1.4 Fault signals

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Incorrect connection of the command inputs
The functioning of the MCU may be impaired.
⇨ For activation of the command inputs for disconnector CLOSED, disconnector OPEN,
earthing switch OPEN and earthing switch CLOSED, do not use any external switching
contacts that are equipped with capacitors > 4.7 nF connected in parallel with the
contact.
Damage due to test voltages
If the specified limits (1 kV, 1 s) are exceeded during dielectric tests according to the
standard IEC 62271-200, the MCU may be damaged by too high test voltages.
⇨ Before performing the dielectric test, remove the connecting plugs at the MCU.
Fault signals at the unit are displayed via a red flashing LED status indicator.
Possible causes for a fault signal:
▪ Only MCU-MH and MCU-MH-MOD: An incorrect sense of rotation of the motor was
detected while moving the operating mechanism from disconnector OPEN / earthing
switch OPEN position to disconnector CLOSED / earthing switch CLOSED position.
▪ There is an internal MCU fault (watchdog).
▪ The feedback monitoring time (runtime monitoring of the operating mechanism) for
protecting the drive motor and the mechanical system was exceeded.
▪ A command for moving the operating mechanism is applied to the active command inputs
(disconnector CLOSED / disconnector OPEN / earthing switch CLOSED / earthing
switch OPEN) for more than 5 minutes, although existing interlocking conditions prevent the
execution of this command.
▪ A command is applied to one of the active command inputs (disconnector CLOSED /
disconnector OPEN / earthing switch CLOSED / earthing switch OPEN) for more than
5 minutes, although the associated switching operation was completed successfully.
Clearing the fault mode
Options for clearing the fault mode after the cause for the fault mode was eliminated:
▪ Only MCU-MH and MCU-MH-MOD: Via the reset pushbutton at the unit (operation of the
reset pushbutton: Insert a thin, pointed object through the opening on the front).
▪ Switch the auxiliary voltage off and on again.
Examples for flashing code of LED status indicator
1
0
1
0
1
0
1
0
Fig. 191: Flashing code
The following table shows the fault coding of the flashing codes for all versions of the MCU.
8DJH • Installation and Operating Instructions • Version 11 • 500-8384.9
NOTICE
NOTICE
LED lights up permanently
1
LED flashes 1x
2
t
LED flashes 2x
3
t
LED flashes 7x
4
t
t