Mitsubishi Electric 800 Series Hardware Instruction Manual page 94

 Checking the inverter operating status by using the start signal input to the inverter and the
Inverter running signal output from the inverter ... (c)
The Inverter running (RUN) signal is output when the inverter is running. (The RUN signal is assigned to terminal RUN in the
initial setting.) Check if the RUN signal is output while a start signal (the STF/STR signal for forward/reverse rotation command)
is input to the inverter. Even after the start signal is turned OFF, the RUN signal is kept output until the inverter makes the motor
to decelerate and to stop. For the logic check, configure a sequence considering the inverter's deceleration time.
Power ON
supply
ON
STF
ON
RH
Pr. 13 Starting
frequency
Reset
processing
ON
RY
ON
RUN
 Checking the motor operating status by using the start signal input to the inverter and the
Output current detection signal output from the inverter ... (d)
The Output current detection (Y12) signal is output when the inverter operates and currents flows into the motor.
Check if the Y12 signal is output while a start signal (the STF/STR signal for forward/reverse rotation command) is input to the
inverter. The Y12 signal is initially set to be output at 150% inverter rated current. Adjust the level to around 20% using no load
current of the motor as reference with Pr.150 Output current detection level.
Like the Inverter running (RUN) signal, even after the start signal is turned OFF, the Y12 signal is kept output until the inverter
stops the output to a decelerating motor. For the logic check, configure a sequence considering the inverter's deceleration time.
 Backup method which does not use 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 signals 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 follows 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.
OFF
OFF
DC injection brake
operation point
DC injection
brake operation
Time
OFF
OFF
3. PRECAUTIONS FOR USE OF THE INVERTER
3.7 Failsafe system which uses the inverter
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