4-284
■ PG feedback setting
(1) Over speed operation setting (20-19 to 20-21)
a) When the motor speed exceeds the tuning limit, an error is detected.
If the motor speed feedback exceeds the value of 20-20 (overspeed detection level) for the time specified in
20-12 (over speed detection delay time) an over-speed (OS) condition is detected.
b) Overspeed detection selection (20-19) specifies the stop method for the inverter in case of an overspeed
condition.
(2) PG Speed deviation setting (20-22 to 20-24)
a) When the speed deviation (difference between the set speed and the actual motor speed) exceeds the
tuning limit, an error is detected.
b) If the speed deviation is greater than the value of 20-23 (deviation detection level) for the time specified in
20-24 (deviation detection delay time), a speed deviation (DEV) is detected.
c) Speed deviation is based on the reference frequency ± speed deviation width, parameter 20-23.
d) Speed deviation detection selection (20-22) specifies the stop method for the inverter in case of a speed
deviation condition.
(3) PG detection setting (20-25 to 20-26)
a) When the inverter no longer received pulses fro, the PG feedback for the time specified in 20-26 a PG
open condition is detected.
b) PG open detection selection (20-25) specifies the stop method for the inverter in case of a PG open
condition.
Refer to figure 4.4.117 for the PG fault detection block diagram.
ABSOLUTE
+
-
+
-
+
-
+
-
+
-
20-24
20-26
20-21
Fout
(after
SFS)
Speed
feedback
+
-
20-23
Duning momentary
power loss
During
B.B.
(01-08)Fmin
0% SPEED
20% SPEED
20-20
DEV Det Time
PGO Det Time
OS Det Time
DEV fault
PGO fault
OS fault
Figure 4.4.117 Logic diagram PG feedback failure detection
(4) Set PG pulse (20-27)
a) Set PG of pulse number of the encoder for phase A or phase B for each cycle
b) If a gearbox is used between the motor and PG the gear ratio can be set with parameter 20-30 and 20-31.
(5) PG rotation direction (20-28)
Parameter is used to set the motor direction and PG direction. Make sure phase A or phase B is leading for motor
forward direction operation.