Hitachi SJ300-037HFE 사용자 설명서

SJ300 Inverter

Oper

ati
ons

and Monitor

ing

The purpose of the electronic thermal setting is to protect the motor from overloading, 
overheating and being damaged. The setting is based on the rated motor current. The inverter 
calculates the thermal rise (heating) of the motor using the current output to the motor squared, 
integrated over the time spent at those levels. This feature allows the motor to draw excessive 
current for relatively short periods of time, allowing time for cooling.

The Thermal Warning output [THM] turns ON to provide a warning before the inverter trips for 
electronic thermal protection. You can set a unique thermal protection level for each of the 
three motor profiles, as shown in the table below.

For example, suppose you have inverter model 
SJ300-110LFE. The rated motor current is 46A. 
The setting range is (0.2 * 46) to (1.2 *46), or 
9.2A to 55.2A. For a setting of B012=46A 
(current at 100%), the figure to the right shows 
the curve.

The electronic thermal characteristic adjusts the 
way the inverter calculates thermal heating, 
based on the type of torque control the inverter 
uses.

CAUTION: When the motor runs at lower 
speeds, the cooling effect of the motor’s internal 
fan decreases.

11, 12, 13, 14, 15,
AL0 – AL2

B034

Notes: 
• The two outputs [RNT] and [ONT] share the 

same time threshold parameter, B040. 
Typically, you will use either the [RNT] or the 
[ONT] output only—not both at once.

• These outputs are useful for the notification 

that a preventative maintenance interval has 
expired.

CM2

13

14

15

11

12

See I/O specs on page 

Inverter output 
terminal circuit

Example: (Requires output configuration—
see page 

.)

RY

+
–

RNT or
ONT

B012 / B212 

/ B312

Electronic thermal setting (calculated 
within the inverter from current output) 

Range is 0.2 * rated current to

1.2 * rated current

Trip

time (s)

Trip current at 60 Hz

60

0.5

0

53.4

69

92

A

116% 150%

200%