Failsafe System Which Uses The Inverter - Mitsubishi Electric FR-A820-00046 (0.4K) Instruction Manual

3.7

Failsafe system which uses the inverter

When a fault is detected by the protective function, the protective function activates and outputs the Fault signal. However, the
Fault signal may not be output at an inverter's fault occurrence when the detection circuit or output circuit fails, etc. Although
Mitsubishi assures the best quality products, provide an interlock which uses inverter status output signals to prevent accidents
such as damage to the machine when the inverter fails for some reason. Also at the same time consider the system
configuration where a failsafe from outside the inverter, without using the inverter, is enabled even if the inverter fails.
 Interlock method which uses the inverter status output signals
By combining the inverter output signals to provide an interlock as shown below, an inverter failure can be detected.
No. Interlock method
Inverter protective function
a
operation
b Inverter operating status
c Inverter running status
d Inverter running status
• When using various signals, assign the functions to Pr.190 to Pr.196 (Output terminal function selection) referring to
the table on the left.
Output
signal
Positive logic
ALM 99
RY 11
RUN 0
Y12 12
NOTE
• Changing the terminal assignment using Pr.190 to Pr.196 (Output terminal function selection) may affect the other
functions. Set parameters after confirming the function of each terminal.
 Checking by the output of the inverter fault signal ... (a)
When the inverter's protective function activates and the inverter trips, the Fault (ALM) signal is output. (The ALM signal is
assigned to terminal A1B1C1 in the initial setting). With this signal, check that the inverter operates properly. In addition,
negative logic can be set. (ON when the inverter is normal, OFF when the fault occurs.)
Inverter fault occurrence
(trip)
ALM
(when output
at NC contact)
RES
 Checking the inverter operating status by the Inverter operation ready signal output from the
inverter ... (b)
The Inverter operation ready (RY) signal is output when the inverter power is ON and the inverter becomes operative. Check
if the RY signal is output after powering ON the inverter.
132
3. PRECAUTIONS FOR USE OF THE INVERTER
3.7 Failsafe system which uses the inverter
Operation check of an alarm contact.
Circuit error detection by negative logic.
Operation ready signal check.
Logic check of the start signal and running signal.
Logic check of the start signal and output current.
Pr.190 to Pr.196 setting
Negative logic
199
111
100
112
ON OFF
OFF
ON
Reset processing
(about 1 s)
Reset ON
Check method
Time
Used signals
Fault output (ALM) signal
Inverter operation ready (RY) signal
Start (STF or STR) signal
Inverter running (RUN) signal
Start (STF or STR) signal
Output current detection (Y12) signal
Refer to
page
460
456
456, 502
464, 502