Hitachi WJ Series User Manual page 124

Chapter 8
 Changing the heat dissipation characteristics of electronic thermal
A
 When "Electronic thermal decrease function enable [b910]" is set to other than "Disable (00)",
the electronic thermal for motor and the electronic thermal for inverter operate independently.
 When the output current is less than 110% of the electronic thermal level (when the reduction
rate is × 1.0), the electronic thermal load ratio for the motor is subtracted.
 The subtraction characteristics can be set in "Electronic thermal decrease function enable
[b910]". Set according to the heat dissipation characteristics of the motor.
Code Item
Electronic
thermal
[b910] decrease
function
enable
Electronic
thermal
[b911]
decreasing
time
Electronic
thermal
[b912]
decreasing
time constant
Electronic
thermal
[b913]
accumulation
gain
 Set the subtraction rate in [b911]/[b912]. Check the thermal time constant of the motor with the
!
motor manufacturer. Also, set a larger value with sufficient margin for the characteristics of the
motor to be used.
 For [b913], adjust the value as large as possible based on [(trip time of electronic thermal time
limit characteristic) / (motor overload tolerance time)] × 100% if the motor overload tolerance
value is available.
 Even if the setting value of [b911]/[b912]/[b913] is equal to or greater than the default setting,
if the value is not appropriate for the motor characteristic value, the motor may burn out. For
these settings, set a value that is sufficiently larger than the motor characteristic value.
 If the motor characteristic value is not available, use with [b910] = 00.
Mandatory Setting for Motor Drive and Test Run
The doubled counters are cleared every 10 minutes each. The
timing of clearing is shifted by 5 minutes and is performed
alternately.
Subtract at the rate that the load ratio becomes 0% from 100%
in 10 minutes.
Subtract at the rate that the load ratio becomes 0% from 100%
in the set time in [b911].
Subtract the load ratio with the set time in [b912] as the time
constant.
Subtraction time setting when [b910] is 02.
Note that if the set value is less than the default setting (600
(s)), the protection will be slow and the motor will easily burn
out.
Subtraction time constant when [b910] is 03.
Note that if the set value is less than the default setting (120
(s)), the protection will be slow and the motor will easily burn
out.
The load ratio for each calculation cycle of the electronic
thermal for the motor multiplied by this setting value is
accumulated as the load ratio. × 1 times at default setting of
100%. Note that if the set value is less than the default setting
of 100.0 (%), the protection will be slow and the motor will
easily burn out.
8-1-11
Description Data
00
01
02
03
0.10 to
100000.00 (s)
0.10 to
100000.00 (s)
1.0 to 200.0 (%)