Ssm Function - Mitsubishi Electric 800 Series Instruction Manual

5.4

SSM function

This function is used to determine that the motor speed (output frequency) has exceeded the specified value.
To use this function, specifications and operating conditions of motor speed estimation must be satisfied. (Refer to
Pr. Name
Monitoring speed
*1
S001
selection
*2 SSM frequency
S019
S020 SSM hysteresis width
S021 SSM output retention
time
*1 To use the SSM function, set Pr.S001 = "1". When the SSM function is activated while Pr.S001 = "0 (initial value)", "E.SAF" (fault detail code 71)
is displayed.
*2 When Pr.S019 = "0", the SSMS signal remains ON while the inverter is stopped, and remains OFF during operation.
 Basic operation
• Speed monitoring is started by turning OFF the SSM command (SSMC) signal.
• When the motor speed is equal to or less than the Pr.S019 setting, the SSM output (SSMS) signal turns ON.
• The SSMS signal turns OFF when the motor speed exceeds the Pr.S019 setting.
• The SSMS signal turns ON when the motor speed decreases to be equal to or less than the value calculated by the
following: (Pr.S019 - Pr.S020).
• Speed monitoring is terminated by turning ON the SSMC signal.
NOTE
• While the SSMC signal is ON, the SSMS signal remains OFF regardless of the motor speed.
Initial Setting range
value
0 0
1
6 Hz 0 to 60 Hz
5 Hz 0 to 15 Hz
0 s 0 to 3600 s
Output frequency
Pr.S019
Lower limit
SSM command
ON
(SSMC)
SSM output
ON
(SSMS)
Description
Speed monitoring is disabled.
Monitoring is enabled using the estimated speed.
Set the level to detect the overspeed.
Set the hysteresis width for the overspeed judgment level.
The lower limit is calculated by the following: (Pr.S019 -
Pr.S020). When the Pr.S020 setting is larger than the Pr.S019
setting, the lower limit is 0 Hz.
Set the time period to retain the SSM output (SSMS) signal
status immediately before the STO function is activated.
Pr.S020
ON
ON
Speed monitoring
page 7.)
Time
5. Safety Sub-Functions
5.4 SSM function
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