Mitsubishi Electric FR-A700 Instruction Manual page 698

Special operation
Setting before the operation (Pr. 144, Pr. 359, Pr. 369)
When performing encoder feedback control under V/f control, set the number of motor poles in
Pr. 144 "Speed setting switchover" according to the motor used. Under advanced magnetic flux
vector control, the Pr. 81 "Number of motor poles" setting is made valid and the Pr. 144 setting
is invalid.
Set the rotation direction and the number of encoder pulses of the encoder using Pr. 359
"Encoder rotation direction" and Pr. 369 "Number of encoder pulses".
NOTES When "0, 10, 110" is set in Pr. 144 and the inverter is started, error E.1 to E.3 occurs.
When "102, 104, 106, 108" is set in Pr. 144, the value subtracting 100 is set as the number
of motor poles.
b
CAUTION:
● If the number of motor poles is wrong, control at correct speed can not be
performed. Always check before operation.
● Encoder feedback control can not be performed when the setting of encoder
rotation direction is wrong. (Inverter operation is enabled.) Encoder rotation direc-
tion can be checked with the rotation direction display of the parameter unit.
Selection of encoder feedback control (Pr. 367)
When a value other than "9999" is set in Pr. 367 "Speed feedback range", encoder feedback
control is valid.
Using the set point (frequency at which stable speed operation is performed) as reference, set
the higher and lower setting range. Normally, set the frequency converted from the slip amount
(r/min) of the rated motor speed (rated load). If the setting is too large, response becomes slow.
Fig. 6-260: Setting the range of the speed feedback range
Example The rated speed of a 4-pole motor is 1740r/min (60Hz)
Calculation of the slip speed:
Slip Nsp= Synchronous speed - Rated speed
Frequency equivalent to slip (fsp):
fsp
6 - 518
Speed feedback range
Set value
(Set command)
= 1800 − 1740 (r/min)
= 60Hz
= (Nsp × Number of poles)/120
= (60 × 4)/120
= 2Hz
Driven load Regeneration load
Parameter
I001630E