Mitsubishi Electric FR-A800, Instruction Manual

Page: 873 / 1042

Parameters (G) Control parameters
FR-A800 5 - 693
Setting before operation (Pr. 144, Pr. 359, Pr. 369)
●
When driving with V/F control and the encoder feedback control, set the number of motor poles
in Pr. 144 "Speed setting switchover" in accordance with the applied motor. During Advanced
magnetic flux vector, the Pr. 81 "Number of motor poles" setting is used, so the Pr. 144 setting does
not need to be changed.
●
Using Pr. 359 "Encoder rotation direction" and Pr. 369 "Number of encoder pulses", set the rotation
direction and the number of pulses for the encoder.
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.
●
For example, when the rated speed of a motor (4 poles) is 1740 r/min at 60 Hz,
Slip Nsp = Synchronous speed – Rated speed
= 1800 – 1740
= 60 (r/min)
Frequency equivalent to slip (fsp) = Nsp × Number of poles/120
= 60 × 4/120
= 2 (Hz)
NOTES When the inverter is operated with Pr. 144 = "0, 10, 110", it will cause E.1 to E.3.
When set to Pr. 144 = "102, 104, 106, 108", number with 100 subtracted will be set as the number
of poles.
When Pr. 81 is set, setting value for Pr. 144 will be automatically changed, but even if Pr. 144 is
changed, Pr. 81 will not automatically change.
Control with correct speed is not possible if the number of poles for the applied motor is incorrect.
Make sure to confirm before operation.
Encoder feedback control is not possible when the rotation direction setting of the encoder is
incorrect. (Operation of the inverter is possible.)
Confirm with the rotation direction indicator on the parameter unit.
I001630E
Fig. 5-346: Setting the range of the speed feedback range
Speed feedback range
Set value
(Set command)
Driven load Regeneration load