131
5. Speed Control
5.8 Avoiding motor overrunning
1
2
3
4
5
6
7
8
9
10
NOTE
• When the automatic restart after instantaneous power failure function is selected (
Pr.57 Restart coasting time
≠
"9999") and
the setting value for the number of encoder pulses is lower than the actual number of pulses, the output speed is limited with
the synchronous speed of the value of
Pr.1 Maximum frequency
+
Pr.873
.
• When a regenerative driving torque limit is applied and the speed limit function activates, the output torque may drop suddenly.
Also, when the speed limit function activates during pre-excitation operation, output phase loss (E.LF) may occur.
If the setting for the number of encoder pulses is confirmed as correct, it is recommended that
Pr.873
be set to the maximum
value (400 Hz).
• Even if the set frequency is lowered after inverter operation, the speed limit value is not lowered. During deceleration, the
speed is limited at frequency command value +
Pr.873
.
Deceleration check (Pr.690)
• This function can stop the inverter output when the motor is accelerated accidentally during rotation. This prevents a
malfunction due to incorrect encoder pulse settings.
• When the difference between the actual motor speed and the speed command value exceeds 2 Hz, the deceleration check
starts.
• If the motor does not decelerate within the time period set in
Pr.690
, the speed deviation excess detection (E.OSD) is
activated to shut off the inverter output.
NOTE
• The deceleration check is enabled in the speed control of the Vector control.
• If the protective function (E.OSD) is activated due to deceleration check, check whether the
Pr.369 Number of encoder
pulses
setting is correct.
• When the motor accelerates slowly (as a reference, when the frequency increment is less than 2 Hz/s), the protective function
may not be activated even when the motor does not decelerate.
Parameters referred to
Pr.285 Overspeed detection frequency
Pr.369 Number of encoder pulses
Motor speed
Time
Motor coasting
Fault output
(ALM)
ON
Pr.690
E.OSD
Speed command
2Hz
Summary of Contents for FR-E800
Page 17: ...16 1 Introduction 1 3 Related manuals MEMO ...
Page 51: ...50 2 Basic Operation 2 8 I O terminal function assignment MEMO ...
Page 89: ...88 3 Parameters 3 4 Parameter list by function group number MEMO ...
Page 135: ...134 5 Speed Control 5 9 Troubleshooting in the speed control MEMO ...
Page 153: ...152 6 Torque Control 6 7 Troubleshooting in torque control MEMO ...
Page 195: ...194 8 E Environment Setting Parameters 8 18 Current average value monitor signal MEMO ...
Page 237: ...236 10 D Operation Command and Frequency Command 10 6 Operation by multi speed setting MEMO ...
Page 339: ...338 13 T Multi Function Input Terminal Parameters 13 9 Start signal operation selection MEMO ...
Page 455: ...454 16 G Control Parameters 16 13 Speed smoothing control MEMO ...
