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UG 6946 / 25.11.19 en / 188A
The UG 6946 has to be connected according to connection examples
or in a similar way. The connection of DC- motors is made as with single
phase AC-motors.
L1 - L2 - L3
The measuring wires L1-L2-L3 have to be connected directly to the win-
dings of the monitored motor (not via transformers) in order to provide a
correct broken wire detection for the connection wires and motor windings.
The motor windings must not be disconnected from the measuring wi-
res by motor contactors, because broken wire detection is activated and
standstill monitoring is disabled.
Interference to the measuring wires should be avoided as no standstill
may be detected by the UG 6946. If possible the measuring wires should
be run separately from the motor wires or screened wires should be used.
In this case the screen can be connected at the motor side.
A1 - A2
Connection of the auxiliary supply, recommended fuse : 2A.
13-14, 23-24
Safety output contacts, connection according to the connection examples
or similar.
Recommended fuse: 5 A fast acting, to avoid welding of the contacts in
the case of external wiring or component failures. See also technical data.
X1 - X2 (feedback circuit)
Connection of NC contacts of external components or contactors for con-
tact re-enforcement, must be linked if not used.
X2 - X3
Connection for manual or auto reset, connection is made according to the
required application. When monitoring DC motors or in the case of DC-
braking the broken wire / offset failure will be shown during operation. In
this case the terminals must be linked because if storing the failure would
not allow activation of the safety contacts at standstill.
MU1, MU2 (at variant /xx1 only)
Using the inputs MU1 and MU2 the standstill detection could be muted.
The signal on the inputs must be between DC 10 and 26.4 V against A2. If
muting is selected on these inputs the standstill detection is disabled. The output
relays are energised and monitoring of broken wire, offset and simultaneity of
the measuring signals is not operated.
MU1 MU2 Mode
0 0 Muting
deactivated
1 1 Muting
activated
WARNING
Attention
The terminals X1-X2-X3 have electrical connections to the measu-
ring inputs L1-L2-L3. Volt free contacts must be used for bridging.
If terminal X3 should be controlled by a PLC via an interface relay
this must have the necessary insulation between the motor voltage
(measuring input) and PLC potential.
Connection of UG 6946
Motors with switched windings
(e.g. star delta starters, reversing circuits, multi speed motors)
With these applications please make sure, that the measuring inputs must
be linked via the motor windings. An open connection will result in broken
wire indication and disable the safety contacts.
When connecting the UG 6946 to a 3-phase motor with star delta starter
the star contactor must be energized while the motor is switched off, in
order to achieve closed circuits between L1-L2-L3 via the motor windings.
If it is not possible to switch in the star contactor after the motor is swit-
ched off, the measuring inputs of the UG 6946 have to be connected
like a single phase connection. L2-L3 are bridged and connected to one
end of a motor winding and L1 to the other end of the same winding.
For reversing circuits and multi speed motors please follow the same pro-
cedure.
If in a 3-phase connection of UG 6946 windings are switched over, and
the interruptions of the measuring circuits are longer then 2 s, the stand-
still monitor detects broken wire. In order not to store this failure, the unit
should work with auto reset.
Operation with DC motors
The UG 6946 can be used on DC motors if these generate a remanence
voltage during run down.
The connection is made similar as with a single phase motor.
As the remanence voltage in this case is normally a DC voltage the unit
will detect a broken wire / offset failure and indicate it on LED „ERR“.
Taking this in mind and operating the unit with auto reset for these failures
the unit can be used for safety standstill monitoring.
Operation with electronic motor controller
(inverters, DC-brakes)
The operation of UG 6946 to detect standstill on motors with electronic
motor control is possible, if the output voltage of the motor controller drops
under the adjusted response value on standstill. (No position control on
inverters, no DC voltage on brakes after standstill).
If the inverter produces a DC offset or a DC brake is active, an offset or
broken wire failure is indicated on LED „ERR“. This error resets automati-
cally if on terminals X2-X3 automatic reset is selected.
When there are inverters in the installation it is recommended to use
screened measuring wires to the motor. The screen can be connected
to the motor.
!
Attention
If the motor current is run down by inverters or softstop modules in a
slow way the motor may be de-magnetised. It is necessary to check if
the remaining remanence voltage is sufficient to guarantee a correct
and safe standstill monitoring. At high frequencies an increasing
damping of the measuring inputs has to be taken into account (see
technical data Measuring input „response value dependant on
frequency“).
Operation Notes
