20
UG 6946 / 25.11.19 en / 188A
green-red LED „UH“:
green on, when operation
yellow on, when muting operation
red on, with internal error
yellow-green LED „OUT“:
yellow on, at EMK > U
an
flashes green at time progression of t
s
permanent on, when output contacts
are enable
red LED „ERR“:
flashes at error
(see flashing codes)
Terminal designation
Signal description
L1-L2-L3
Connection to monitored motor
31-32
Forcibly guided indicator output
13-14, 23-24
Forcibly guided NO contacts for release circuit
X1-X2
Connection of feedback circuit
(for external contactors)
X2-X3
Manual reset for external faults
A1-A2
Auxiliary supply (U
H
)
MU1, MU2
Muting inputs
Circuit Diagrams
Connection Terminals
Indicators
The UG 6946 can be used for standstill detection on all 3-phase, sin-
gle phase and DC motors, that generate a voltage caused by remanence
when freewheeling. As the voltage level U
an
for standstill monitoring and
the time delay ts, after detection of standstill until the safety relays are
switched on, are adjustable, the function can be adopted to different
motors and applications.
Basic function of UG 6946
The auxiliary voltage is connected to the terminals A1-A2; the LED „UH“
lights up green. On undervoltage or missing auxiliary supply the safety
outputs are disabled.
A motor connected to the terminals L1-L2-L3 of the UG 6946 generates
a voltage when running down (motor is switched off). The voltage is pro-
portional to the speed and caused by residual magnetism (remanence).
This voltage is measured redundant on 2 input channels via the terminals
L2 and L3 with L1 as common reference.
If the voltage drops on both channels below the adjusted value U
an
, the
unit detects standstill. When the terminals X1-X2 of the feedback circuit
are bridged and the time delay ts is finished, the safety contacts 13-14,
and 23-24 close. All contact paths have 2 forcibly guided contacts of 2
safety relays wired in series.
At the same time the LED „OUT“ lights green. During time delay ts this
LED flashes.
If the voltage measured on terminals L1-L2-L3 of UG 6946 rises over
the adjusted value plus hysteresis in at least one channel (the motor is
switched on or the shaft turns mechanically), the forcibly guided output
contacts are switched off immediately (contacts 13-14 and 23-24 open).
The LED „OUT“ lights yellow (= U
an
over adjusted value).
Feedback circuit X1 - X2
If the safety contacts 13-14 and 23-24 control external contactors/com-
ponents (e.g. to re-enforce or multiply the contacts) the safety function of
them must be monitored.
This is done with the feed back circuit (terminals X1-X2) to which the
NC contacts of the contactors/components must be connected. (see also
wiring diagrams).
The UG 6946 will only enable its safety output if the feedback loop X1-X2
is closed while standstill is detected, i.e. the external contactors/compon-
ents are in initial state (NC contacts are closed).
The feedback circuit X1-X2 must be closed as long as the safety outputs
(because of running motor or external failure) are not enabled. If not the
failure „feedback circuit“ is indicated.
If the feedback circuit is not used, the terminals X1-X2 must be bridged.
Function
UG 6946.02
UG 6946.02/xx1
UG 6946.22
UG 6946.22/xx1
X2
A2
nc
14
X1
L2
13
X2
nc
L3
X3
nc
nc
M11879_a
A1+
L1 nc
24
23
13
K1
K2
31
14
32
23
24
31 32
X2
A2
nc
14
X1
L2
13
X2
nc
L3
X3
nc
nc
M11880_a
A1+
L1 nc
24
23
13
K1
K2
31
14
32
23
24
31 32
MU2
MU1
X2
A2 31 32
nc
14
X1
L2
13
X2
nc
L3
X3
nc
nc
M11881_a
A1+
L1 nc
13
K1
K2
23
31
14 24
32
24
23
X2
A2
nc
14
X1
L2
13
X2
nc
L3
X3
nc
nc
M11882_a
A1+
L1 nc
MU2
MU1
31 32
13
K1
K2
23
31
14 24
32
24
23