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Failsafe of the system which uses the inverter
1
WIRING
1.9 Failsafe of the system which uses the inverter
When a fault occurs, the inverter trips to output a fault signal. However, a fault output signal
may not be output at an inverter fault occurrence when the detection circuit or output circuit
fails, etc. Although Mitsubishi assures best quality products, provide an interlock which
uses inverter status output signals to prevent accidents such as damage to machine when
the inverter fails for some reason and at the same time consider the system configuration
where failsafe from outside the inverter, without using the inverter, is enabled even if the
inverter fails.
(1) Interlock method which uses the inverter status output signals
By combining the inverter status output signals to provide an interlock as shown
below, an inverter alarm can be detected.
1) Check by the output of the inverter fault
signal
When the fault occurs and trips the
inverter, the fault output signal (ABC
signal) is output (ABC signal is assigned
to terminal ABC in the initial setting).
Check that the inverter functions properly.
In addition, negative logic can be set (on
when the inverter is normal, off when the
fault occurs).
No
Interlock
Method
Check Method Used Signals Refer to Page
1)
Inverter
protective
function
operation
Operation check of an
alarm contact
Circuit error detection by
negative logic
Fault output signal
(ABC signal)
111
2)
Inverter running
status
Operation ready signal
check
Operation ready signal
(RY signal)
111
3)
Inverter running
status
Logic check of the start
signal and running signal
Start signal
(STF signal, STR signal)
Running signal (RUN
signal)
109, 111
4)
Inverter running
status
Logic check of the start
signal and output current
Start signal
(STF signal, STR signal)
Output current detection
signal (Y12 signal)
109, 111
ON
Reset processing
(about 1s)
OFF
Reset ON
Output frequency
ABC
(when output
at NC contact)
RES
Inverter alarm occurrence
(output shutoff)
Time
OFF
ON