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Application Precautions
There are two ways to set a speed limit: using an input from an analog input terminal and setting a speed limit
in d5-04. The inputs methods for a speed limit are listed in the following table.
Torque Limit Operation Examples
Operation examples will be described separately for winding operation, in which the speed and motor torque
are in the same directions, and rewinding operation, in which the speed and motor torque are in opposite direc-
tions.
Winding Operation
In a winding operation, the line (speed) and torque generated by the motor are in the same direction. For the
winding operation, both the speed limit and the torque reference input are positive. The motor will accelerate
when the torque reference input is larger than the load and will decelerate when it is smaller than the load. If
the motor turns faster than the speed limit, a negative compensation value is output from the speed limiter cir-
cuit. When the speed then drops below the speed limit, a positive compensation value is output. The torque
compensation is proportional to the ASR proportional gain. When the sum of the torque reference and the
torque compensation output by the speed limiter is the same as the actual load, the motor will stop accelerating
and run at a constant speed.
Rewinding Operation
In a rewinding operation, the line (speed) and torque generated by the motor are in the opposite directions. (In
this example, we’ll assume that the line speed is positive and the torque reference input is negative.) For the
rewinding operation, the speed limit is positive and the torque reference input is negative. If the motor turns
faster than the speed limit, a negative compensation value is output from the speed limiter circuit. If the motor
is rotating in reverse, a negative compensation value is output. If the speed is 0 or is below the speed limit, a 0
Speed Limit Input Method
Location of Refer-
ence
Constant Set-
tings
Remarks
Voltage input (0 to ±10 V)
Set in d5-04
d5-03 = 2
-
Between A1 and AC
b1-01 = 1
H3-01 = 1
Set H3-01 to 0 if the speed limit is always
to be positive.
Between A2 and AC
b1-01 = 0
H3-08 = 1
H3-09 = 1
The value will be added to the value input
on A1 to determine the speed limit.
Set H3-03 to 0 if the speed limit input on
A2 is always to be positive.
Turn OFF (V side) pin 2 of DIP switch S1
on the terminal board.
Current input (4 to 20 mA)
Between A2 and AC
b1-01 = 0
H3-08 = 2
H3-09 = 1
The value will be added to the value input
on A1 to determine the speed limit.
Turn ON (I side) pin 2 of DIP switch S1
on the terminal board.
Option board (AI-4B)
(0 to ±10 V)
Between TC1 and TC4
b1-01 = 3
F2-01 = 0
If H3-09 is set to 0, the sum of the input
between TC2 and TC4 will be added the
input between TC1 and TC4 to determine
the speed limit.
IMPORTANT
The direction in which speed is controlled is determined by the sign of the speed limit signal and the direction
of the Run Command.
• Positive voltage applied: The speed in the forward direction will be limited for forward operation.
• Negative voltage applied: The speed in the reverse direction will be limited for reverse operation.
If the direction of motor rotation and the command direction are not the same, speed will be limited to 0 as
long as b5-05 is set to 0.