Mitsubishi Electric FR-A700 Series, Technical Manual

Page: 211 / 550

245
2
P
ARAM
ETE
R
PARAMETER
The setting conditions of related parameters and the
relationship between output frequency and output voltage for
factory setting is indicated in the table in the last page
and figure below.
(1) Load pattern selection [
Pr. 14
]
Allows the optimum V/F characteristic to be selected
according to the load torque characteristic and
operation method.
1) For constant torque load [
Pr. 14 = 0 ]
Set [ Pr. 14 = 0 ] to drive a load which is constant in
load torque if the speed varies, e.g. conveyor,
cart, roll drive.
2) For variable-torque load [
Pr. 14 = 1
]
Set [ Pr. 14 = 1 ] when driving the load whose load
torque varies in proportion to the square of the
speed, e.g. fan or pump.
If the load is a fan or pump, select "for constant-
torque load" in any of the following cases.
When the variable-torque load has been selected,
[
Pr. 1 Maximum frequency ] should be equal to or
less than the [ Pr. 3 Base frequency ] setting
(normally 50Hz or 60Hz) unless the motor
capacity is considerably sufficient. When the
variable-torque load has been selected, the output
voltage is approximately proportional to the
square of the output frequency.
3) For constant torque vertical lift load [
Pr. 14 = 2, 3
]
Set [ Pr. 14 = 2 ] for a vertical lift which is kept in the
driving mode during forward rotation and in the
regenerative mode during reverse rotation. In this
case the torque boost set in [
Pr. 0 Torque boost ] is
made valid during forward rotation and the torque
boost is automatically set to 0% during reverse
rotation as shown below.
Set [ Pr. 14 = 3 ] for an elevated load that is in the
driving mode during reverse rotation and in the
regenerative mode during forward rotation
according to the load weight, e.g. counterweight
system.
When torque is continuously regenerated as
vertical lift load, it is effective to set the rated
voltage in [
Pr. 19 Base frequency voltage ] to prevent
trip due to current at regeneration.
4) Changing of load pattern selection [ Pr. 14 = 4, 5 ]
Set [ Pr. 14 = 4, 5 ] to change the load pattern
selection according to the RT signal.
The RT signal may be replaced by the X17 signal.
Relationship between output frequency and output
voltage for factory setting
(a) When a blower of large load inertia J
(moment of inertia) is accelerated in a short
time.
(b)
For constant-torque load such as rotary
pump or gear pump.
(c) When load torque increases at low speed,
e.g. screw pump.
Output frequency and output voltage when variable-
torque load is selected
A700
= Pr. 1 ?
=
Pr. 3
?
= Pr. 0 ?
60 120
Output frequency (Hz)
Output voltage (%)
0
100
Constant-torque load
= Pr. 14 ?
A700
common
common
[ Pr. 0 ]
[ Pr. 3 ] 50 or 60
Output frequency (Hz)
Output voltage (%)
0
100
[ Pr. 1 ], [ Pr. 3 ]
Variable-torque load
[ Pr. 14 = 1]
For vertical lift load output voltage
[ Pr. 14 ]
setting
RT signal
(X17 signal)
Output characteristics
4
ON
For constant torque load (same as
when the setting is 0)
OFF
For vertical lift (at reverse rotation
boost 0%) (same as the setting 2)
5
ON
For constant torque load (same as
when the setting is 0)
OFF
For vertical lift (at forward rotation
boost 0%) (same as the setting 3)
A700 E700 D700
[ Pr. 0 ]
Forward
rotation
Output frequency (Hz)
Output voltage (%)
0
100
Reverse rotation
(torque boost = 0%)
[ Pr. 3 ]
A700