MITSUBISHI ELECTRIC FR-S520E - Manual (Page 91)

81
Explanation of functions (parameters)
2
F
UNCT
IO
NS
2.3.13 Stall prevention (Pr. 22 , Pr. 23 , Pr. 28 )
•Generally, set 150% (factory setting) in Pr. 22 "stall prevention operation level".
Setting "0" in Pr. 22 disables stall prevention operation.
•To reduce the stall prevention operation level in the high frequency range, set the
reduction starting frequency in Pr. 28 "stall prevention operation reduction starting
frequency" and the reduction ratio compensation factor in Pr. 23.
Formula for stall prevention operation level
•By setting "- - -" (factory setting) in Pr. 23, the stall prevention operation level is
constant at the Pr. 22 setting up to 120Hz.
Set the output current level (% value to the inverter rated current) at which the
output frequency will be adjusted to prevent the inverter from stopping due to
overcurrent etc.
During high-speed operation above the rated motor frequency, acceleration
may not be made because the motor current does not increase. To improve
the operating characteristics of the motor in this case, the stall prevention
level can be reduced in the high frequency region. This function is effective for
performing operation up to the high speed range on a centrifugal separator
etc. Normally, set 60Hz in Pr. 28 "stall prevention operation reduction starting
frequency" and 100% in Pr. 23.
Parameter Name
Factory
Setting
Setting
Range
Remarks
22
Stall prevention operation
level
150% 0 to 200% 
Setting is
enabled
when
Pr. 30 = "1".
23
Stall prevention operation
level compensation factor at
double speed
- - -
0 to 200%,
- - -
- - -: Pr. 22
equally
28
Stall prevention operation
reduction starting frequency
60Hz 0 to 120Hz 
Stall prevention operation level (%) = A + B ×[
Pr. 22-A
]×[
Pr. 23-100
]
Pr. 22-B 100
where, A =
Pr. 28 (Hz) × Pr. 22 (%)
, B =
Pr. 28 (Hz) × Pr. 22 (%)
output frequency (Hz) 120Hz
120Hz
Pr.22
Pr.28
Pr.23
S
ta
ll pr
e
v
en
ti
on
oper
at
ion l
e
ve
l
(%
)
Output
frequency (Hz)
R
educt
io
n
r
a
ti
o
com
p
e
n
sat
ion f
a
ct
or
(%)
="- - -" Pr.23 When
Setting example
(Pr.22=
Pr.23=100%, Pr.28= Hz)
0 80100120
Stall prevention operation level (%)
Output
frequency (Hz)
60
90
75
60
112.5
150
150%,