Failsafe Of The System Which Uses The Inverter - Mitsubishi Electric 800 Series Installation Manualline

3 FAILSAFE OF THE 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. (For
details of each signal, refer to the FR-E800 Instruction Manual (Function).)
No. Interlock method
a Inverter protective function operation
b Inverter operating status
c Inverter running status
d
Inverter running status
*1
This interlock method cannot be used when a PM motor is used.
l When using various signals, assign the functions to Pr.190 to Pr.196 (Output terminal function selection) referring to the
following table.
Output signal
Positive logic
ALM 99
RY 11
RUN 0
Y12 12
CAUTION
l 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 using the Fault signal output from the inverter... (a)
When the inverter's protective function is activated and the inverter output is stopped, 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 using 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.
Check method
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
*1
current.
Pr.190 to Pr.196 settings
ON OFF
ON OFF
Reset processing
(about 1 s)
Reset ON
Negative logic
199
111
100
112
Time
Used signals
Fault (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
31