Hitachi SJ300 Series Instruction Manual page 100

3–32
"B" Group: Fine-Tuning Functions
Constant Torque Characteristic – Selecting the constant torque characteristic for the example
motor gives the curves below. At 2.5 Hz, the output current is reduced by a factor of 0.9 for
given trip times.
Trip current
reduction
factor
x 1.0
x 0.9
x 0.8
0
2.5 5
Free Thermal Characteristic - It is possible to set the electronic thermal characteristic using a
free-form curve defined by three data points, according to the table below.
Function
Name
Code
B015 / B017 / Free-setting electronic
B019 thermal frequency 1, 2, 3
B016 / B018 / Free setting electronic
B020 thermal current 1, 2, 3
The left graph below shows the region for possible free-setting curves. The right graph below
shows an example curve defined by three data points specified by B015 – B020.
Trip current
reduction
factor
x 1.0
x 0.8
Setting range
0
5
Output freq.
Suppose the electronic thermal setting (B012) is set to 44 Amperes. The left graph below shows
the effect of the free setting torque characteristic curve. For example, at (B017) Hz, the output
current level to cause overheating in a fixed time period is reduced by a factor of (B018). The
right graph below shows the reduced trip current levels in those conditions for given trip times.
Trip
time (s)
60
0.5
0
(x)
Reduced trip current at (B017) Hz
Trip
time (s)
60
0.5
Hz 0
60
Reduced trip current at 2.5 Hz
Description
Data point coordinates for Hz axis
(horizontal) in the free-form curve
Data point coordinates for Ampere
axis (vertical) in the free-form curve
Output
current (A)
B020
B018
B016
0
Hz
400
B015 B017 B019 Ax04
(x) = B018 value x 116%
(y) = B018 value x 120%
(z) = B018 value x 150%
A
(y) (z)
A
47.8 62.1 82.8
104% 135% 180%
Range
0 to 400Hz
0.0 = (disable)
0.1 to 1000.
Hz
max. freq.