21
UG 6946 / 25.11.19 en / 188A
Function
Function
Failure monitoring
The UG 6946 includes a number of facilities to to detect failures that could
influence the safety function of the module. The failure check is carried out
on power up of the unit and in cycles during normal operation. If a failure
occurs the output relays switch off. The failure state is indicated with the
LEDs „ERR“ and „UH“.
With safety relevant failures the unit differentiates between external failu-
res (broken wire / offset, simultaneity failure, feedback circuit failure) and
internal failures.
Broken wire / offset failures and feedback circuit failures can be stored
or automatic reset after removing the fault. (see chapter failure storing).
Broken wire / offset
The connection wires between UG 6946 and motor are continuously
monitored for broken wire and on a DC-voltage offset higher then U
an
.
In the case of a broken wire or offset failure the output relays
are switched off immediately and the LED „OUT“ lights yellow.
In addition a failure signal comes up with delay (on broken wire after 2 s
on offset failure after 8 s): the LED „ERR“ flashes with failure code 2 or 3
depending on the failure located either between L1-L2 or L1-L3.
Simultaneity of the measuring signals
As additional safety feature the 2 input signals (L2 and L3) are compared
continuously. This allows to detect also internal failures in one measuring
channel.
If the signals are different for at least 2.5 s (one channel >U
an
the other <U
an
)
simultaneity failure is detected. LED „ERR“ flashes with failure code 5.
If the measured signals return to the same level <U
an
the error remains
stored and the outputs are disabled.
The simultaneity failure is only reset when both channels return to > U
an
.
If after that both channels drop below the setting value, get < U
an
the out
relays will switch on.
Simultaneity of the muting inputs (MU1, MU2)
If the status of MU1, MU2 is different for more than 3 seconds the
simultaneity fault is indicated:
The LED "ERR" flashed code 5.
The simultaneity fault is reset only, when both inputs are low and the reset
it operated.
Failure in feedback circuit X1-X2
As already mentioned the failure code „feedback circuit“ occurs when the
outputs are disabled and there is no connection between terminal X1-X2.
The LED „ERR“ flashes with failure code 4.
Also when both input signals drop now to <U
an
and besides the open feed-
back loop no other failures are present the feedback circuit failure remains
active and the outputs remain disabled.
If the feedback circuit is now closed and the unit is on auto reset for exter-
nal failures (see failure storing) the output relays are enable and switch on.
Potentiometer error
To achieve the required safety when adjusting the voltage threshold for
standstill detection, ech setting function is realised with 2 potentiometers
having one common setting knob. If on 2 corresponding potentiometers a
different setting is detected the potentiometer error U
an
or t
s
is displayed.
To remove the failure please try to readjust the potentipometer. Please
make sure that you feel the detent
Internal device failure
Internal failures are always stored, independent of the reset input X3 and
cause the output relays immediately to switch off, the LED „UH“ to change
it’s colour from green to red.
Examples for internal failures:
•
Failure on safety relays e.g. welded output contacts
•
Internal failures on measuring channels and measuring circuits
•
Internal failures on control circuits for the safety relays
•
failures on setting potentiometers for U
an
and t
s
•
Undervoltage failure (LED „ERR“ flashes with failure code 1)
Failure indication with flash code of LED „ERR“
The flash codes indicate failures caused externally (see diagram flashing
codes for failure indication on page 9).
A series of flash pulses 1-7 followed by a slightly longer space is dis-
played. The flash code indicates the type of failure. If several failures are
present at the same time only the failure with the highest priority (lowest
flash code) is shown. When this failure is removed the other existing failu-
res are displayed in the same way according to their priority.
Failure storing / reset (terminals X2-X3)
With the external failures broken wire/offset and feedback circuit the ope-
rator can choose between manual and automatic reset after the failure is
removed.
X2-X3 open:
manual reset
X2-X3 closed:
automatic reset
!
Attention
The a.m. storing function of the external failures broken wire /offset,
and feedback circuit is not a safety function. I.e. in respect to safety
aspects it can not be regarded as guaranteed. The reset for these
failures must be therefore regarded as auto reset after removing the
faults.
Internal device failures that could occur in seldom cases (e.g.
caused by temporary interference) can be reset by switching the
supply voltage off and on. If a reset is not possible also if the voltage
is applied correctly, the device could be defective and should be sent
back to the manufacturer for examination or repair.