Failsafe System Which Uses The Inverter - Mitsubishi Electric FR-F820-00046 Instruction Manual

Safety stop function

If any of the protective functions shown in the following table is activated, the terminal SO turns OFF.
Error definition
Option fault
Communication option fault
Parameter storage device fault
Retry count excess
Parameter storage device fault
Operation panel power supply short circuit/
RS-485 terminals power supply short circuit

If the internal safety circuit is operated normally, the terminal SO remains ON until E.SAF is displayed, and the terminal SO turns OFF when E.SAF is displayed.

SA is displayed when the terminals S1 and S2 are identified as OFF due to the internal safety circuit failure.

If another fault occurs at the same time as E.SAF, the other fault can be displayed.

If another warning occurs at the same time as SA, the other warning can be displayed.
For more details, refer to the Safety stop function instruction manual (BCN-A23228-001). (A PDF copy of this manual can be found in the enclosed CD-ROM. For
how to use this CD-ROM, refer to
4

FAILSAFE SYSTEM WHICH USES THE INVERTER

When a fault is detected by the protective function, the protective function activates and output a fault signal (ALM). 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.
Interlock method
Inverter protective function Operation check of an alarm contact.
operation Circuit error detection by negative logic.
Inverter operating status Operation ready signal check.
Logic check of the start signal and running
Inverter running status
signal.
Logic check of the start signal and output
Inverter running status
current.
 Backup method outside the inverter
Even if the interlock is provided by the inverter status signal, enough failsafe is not ensured depending on the failure status of the inverter itself. For example, if an
inverter CPU fails in a system interlocked with the inverter's fault, start, and RUN signals, no fault signal will be output and the RUN signal will be kept ON
because the inverter CPU is down.
Provide a speed detector to detect the motor speed and current detector to detect the motor current and consider the backup system such as performing a check
as below according to the level of importance of the system.
• Start signal and actual operation check
Check the motor running and motor current while the start signal is input to the inverter by comparing the start signal to the inverter and detected speed of the
speed detector or detected current of the current detector. Note that the current is flowing through the motor while the motor coasts to stop, even after the
inverter's start signal is turned OFF. For the logic check, configure a sequence considering the inverter's deceleration time. In addition, it is recommended to check
the three-phase current when using the current detector.
• Command speed and actual operation check
Check for a gap between the actual speed and commanded speed by comparing the inverter's speed command and the speed detected by the speed detector.
Inverter
14
WIRING
Operation panel
indication
E.OPT
E.OP1
E.PE
E.RET
E.PE2
E.CTE
page 31.)
Check method
Sensor
(speed, temperature,
air volume, etc.)
To the alarm detection sensor
Error definition
24 VDC power fault
Safety circuit fault
Overspeed occurrence
CPU fault
Internal circuit fault
Used signals
Fault output signal (ALM signal)
Operation ready signal (RY signal)
Start signal (STF signal, STR signal)
Running signal (RUN signal)
Start signal (STF signal, STR signal)
Output current detection signal (Y12
signal)
Controller
Operation panel
indication
E.P24
E.SAF
E.OS
E.CPU
E.5 to E.7
E.13
Refer to
Chapter 5 of the
Instruction Manual.
(Detailed)
Chapter 5 of the
Instruction Manual
(Detailed).
Chapter 5 of the
Instruction Manual
(Detailed)
Chapter 5 of the
Instruction Manual
(Detailed).
System failure