4 Wiring with
4.14 Basic circuits
Operating instructions 05/10 MN05013003Z-EN www.eaton.com 153
4.14.9 Self maintaining
A combination of a series and parallel connection is used to wire a latching
circuit.
Latching is established by contact Q1 which is connected in parallel to I1.
When I1 is actuated and reopened, the current flows via contact Q1 until I2 is
actuated.
Table 24: Self maintaining
Latching circuits are used to switch machines on and off. The machine is
switched on at the input terminals via normally open contact S1 and is
switched off via normally closed contact S2.
S2 breaks the connection to the control voltage in order to switch off the
machine. This ensures that the machine can be switched off, even in the
event of a wire break. I2 is always closed when not actuated.
Alternatively the latching circuit can also be set up with the wire break
function using the “Set” and “Reset” coil functions.
Coil Q1 latches if I1 is activated. I2 inverts the break contact signal of S2 and
only switches if S2 is activated in order to disconnect the machine or in the
event of a wire breakage.
Make sure that both coils are wired up in the correct order in the easy circuit
diagram: first wire the S coil and then the R coil. This will ensure that the
machine will be switched off when I2 is actuated, even if I1 is switched on.
I1uI2----ÄQ1
Q1k
S1 N/O contact at I1
S2 N/C contact on I2
I1 I2 Contact Q1 Coil Q1
000 0
010 0
100
0
110
1
001 0
011 1
101 0
111 1
I1-------SQ1
I2-------RQ1
S1 N/O contact at I1
S2 N/C contact on I2
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