Failsafe System Which Uses The Inverter - Mitsubishi Electric FR-CS84-012 Instruction Manual

3.7

Failsafe system which uses the inverter

When a fault is detected by the protective function, a fault signal is output. However, a 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, refer to the following table and assign the functions by Pr.195 (Output terminal function
selection).
Pr.195 setting
Output signal
Positive logic Negative logic
ALM 99
RY 11
RUN 0
Y12 12
NOTE
• Changing the terminal assignment using Pr.195 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 is activated and the inverter output is shut off, the Fault (ALM) signal is output. (The
ALM signal is assigned to terminals A, B, and C 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.
62
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.
199
111
100
112
ON
OFF
OFF
ON
Reset processing
(about 1 s)
Reset ON
Check method
Time
Used signals
Fault (ALM) signal
Operation ready signal (RY) signal
Start (STF or STR) signal
Running signal (RUN) signal
Start (STF or STR) signal
Output current detection (Y12)
signal
Refer to
page
128
127
127, 145
129, 145