Avoiding Motor Overrunning - Mitsubishi Electric FR-E800 Series Instruction Manual

5.8

Avoiding motor overrunning

Vector Vector Vector PM PM PM
Motor overrunning due to excessive load torque or an error in the setting of the number of encoder pulses can be avoided.
Pr.
Speed deviation excess detection
285
H416
frequency
853
Speed deviation time
H417
*2
873
Speed limit
H415
690
Deceleration check time
H881
*1 This is the overspeed detection frequency under encoder feedback control. (Refer to
*2 The setting is available when a Vector control compatible option is installed.
 Speed deviation excess detection (Pr.285, Pr.853)
• A shutoff can be set for when the deviation between the set frequency and the rotation speed (estimated value) is large,
such as when the load torque is excessive.
• When the difference (absolute value) between the speed command value and the rotation speed (estimated value) is equal
to or higher than the setting value in Pr.285 Speed deviation excess detection frequency for a continuous time equal
to or longer than the setting value in Pr.853 Speed deviation time, the speed deviation excess detection (E.OSD) is
activated to shut off the inverter output.
Fault output
(ALM)
NOTE
• This function is enabled at a frequency equal to or higher than 10% of the rated motor frequency under PM sensorless vector
control.
 Speed limit (Pr.873)
• This function prevents overrunning even when the setting value for and the value of the actual number of pulses are
different. When the setting value for the number of encoder pulses is lower than the actual number of pulses, because the
motor may increase speed, the output frequency is limited with the frequency of (set frequency + Pr.873).
Set speed + Pr. 873 value
Actual speed
at error occurrence
130
5. Speed Control
5.8 Avoiding motor overrunning
Name Initial value
9999
*1
1.0 s
20 Hz
1.0 s
Set frequency
Pr.285
Rotation speed (estimated value)
Time
Pr.853
OFF ON
Speed deviation
excessive fault activated
(E. OSD)
Setting
range
Set the speed deviation excess detection frequency
(difference between the rotation speed (estimated value)
0 to 30 Hz
and the speed command value) at which the protective
function (E.OSD) activates.
9999 No speed deviation excess
Set the time from when the speed deviation excess state
0 to 100 s is entered to when the protective function (E.OSD)
activates.
Set the frequency limit with the set frequency + Pr.873
0 to 400 Hz
value.
Set the time required to shut off output due to
0 to 3600 s
deceleration check.
9999 No deceleration check
page 450).
Value of Pr. 873
Set speed
Speed during
normal operation
Description