SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
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Chapter 4 Explanation of Functions<br />
4.2.29 Electronic thermal protection<br />
The electronic thermal protection function allows you to protect<br />
the motor against overheating. Make settings of this function<br />
based on the rated current of the motor. The inverter will trip for<br />
overheat protection according to the settings.<br />
This function provides optimum overheat protection that is also<br />
designed with the lowering of the motor's cooling performance<br />
at low speeds in mind.<br />
You can configure this function so that the inverter outputs a<br />
warning signal before it trips for electronic thermal protection.<br />
(1) Electronic thermal level<br />
Item Function code Range of data Description<br />
Electronic thermal<br />
setting (calculated within<br />
the inverter from current<br />
output)<br />
b012/b212/b312<br />
(Example) Setting on the <strong>SJ700</strong>-150LFF(0.4-55kW)<br />
Rated current: 64 A<br />
Range of setting: 12.8 A (20%) to 64.0 A (100%)<br />
When 64 A is set as the electronic thermal setting (b012),<br />
the time-limit characteristic is as shown on the right.<br />
Trip time (s)<br />
"0.2 x rated current" to<br />
"1.0 x rated current"<br />
Trip time (s)<br />
Related code<br />
b012/b212/b312: Electronic thermal setting<br />
(calculated within the inverter from current output),<br />
1st/2nd/3rd motors<br />
b013/b213/b313: Electronic thermal characteristic,<br />
1st/2nd/3rd motors<br />
b015/b017/b019: Free setting, electronic thermal<br />
frequency (1) (2) (3)<br />
b016/b018/b020: Free setting, electronic thermal<br />
current (1) (2) (3)<br />
C021 to C025: Terminal [11] to [15] functions<br />
C026: Alarm relay terminal function<br />
C061: Electronic thermal warning level setting<br />
See the example below.<br />
(Example) Setting on the<br />
<strong>SJ700</strong>-750LFF(75-150kW)<br />
Rated current: 149 A<br />
Range of setting: 29.8 A (20%) to 149 A (100%)<br />
When 149 A is set as the electronic thermal setting<br />
(b012), the time-limit characteristic is as shown on the<br />
right.<br />
60<br />
3.0<br />
60<br />
0.5<br />
0 69.8 96 128<br />
(109%)(150%)<br />
(200%)<br />
Motor current (A)<br />
(Ratio to the rated<br />
current of inverter)<br />
0 158 223.5<br />
(106%) (150%)<br />
268<br />
(180%)<br />
Motor current (A)<br />
(Ratio to the rated<br />
current of inverter)<br />
(2) Electronic thermal characteristic<br />
The frequency characteristic set as the electronic thermal characteristic is integrated with the value of<br />
"b012", "b212", or "b312".<br />
The cooling-fan performance of a general-purpose motor lowers when the motor speed is low. So load<br />
(current) is decreased.<br />
The reduced-torque characteristic is designed to match the heat generation by <strong>Hitachi</strong>'s general-purpose<br />
motors.<br />
Item Function code Data Description<br />
00 Reduced-torque characteristic<br />
Electronic thermal<br />
b013/b213/b313 01 Constant-torque characteristic<br />
characteristic<br />
02 Free setting of electronic thermal characteristic<br />
4 - 37
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