Table of Contents
7.8.2 Electronic thermal protection
The electronic thermal protection function allows you to protect the motor against overheating. Make
settings of this function based on the rated current of the motor. The inverter will trip for overheat protection
according to the settings.
This function provides optimum overheat protection that is also designed with the lowering of the motor's
cooling performance at low speeds in mind.
You can configure this function so that the inverter outputs a warning signal before it trips for electronic
thermal protection.
(1) Electronic thermal level
Item
Electronic thermal
setting (calculated within
the inverter from current
output)
Trip time(s)
60
3.0
0
109%
(2) Electronic thermal characteristic
The frequency characteristic set as the electronic thermal characteristic is integrated with the value of
"b012" or "b212".
The cooling-fan performance of a general-purpose motor lowers when the motor speed is low. So load
(current) is decreased.
The reduced-torque characteristic is designed to match the heat generation by Hitachi's general-purpose
motors.
Item
Electronic thermal
characteristic
(a) Reduced-torque characteristic
The time-limit characteristic determined by the value of "b012" or "b212" is integrated with each frequency
multiplied by reduction scales.
Reduction
scale
X1.0
X0.8
X0.6
0
5
16
0
6
20
Base frequency
Function code
"0.2 x rated current" to
b012/b212
"1.0 x rated current"
150%
200%
Motor current (A)
(Ratio to the
rated current of
inverter)
Function code
b013/b213
(Example) 015L**, Base frequency60Hz, （rated current7.1A = b012）
60Hz （Reduction scale：x1.0）
Trip time (s)
Inverter output
frequency (Hz)
50
60
(Ratio to the rated current of inverter)
Chapter 7 Explanation of Functions
Range of data
See the example below.
Data
00
Reduced-torque characteristic
01
Constant-torque characteristic
02
Free setting of electronic thermal characteristic
60
3.0
0
7.7
10.7
14.2[A]
(109%)
(150%
(200%)
)
Motor current (A)
7 - 61
Description
Description
20Hz （Reduction scale：x0.8）
Trip time (s)
60
3.0
0
6.2
8.5
(87.2%)
(120%
)
Motor current (A)
(Ratio to the rated current of inverter)
11.4[A]
(160%)
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