Thermal Warning Signal - Hitachi SJ300 Series Instruction Manual

Valid for
outputs:
Required
settings:
Notes:
• The two outputs [RNT] and [ONT] share the
• These outputs are useful for the notification
Thermal Warning
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
Signal
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.
B012 / B212
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.
Opt.
Symbol Function Name
Code
11, 12, 13, 14, 15,
AL0 – AL2
B034
same time threshold parameter, B040.
Typically, you will use either the [RNT] or the
[ONT] output only—not both at once.
that a preventative maintenance interval has
expired.
Function
Function/Description
Code
Electronic thermal setting (calculated
/ B312 within the inverter from current output)
Output
Description
State
Example: (Requires output configuration—
see page 3–53.)
Inverter output
terminal circuit
RNT or
ONT
RY
See I/O specs on page 4–9.
Data or Range
Range is 0.2 * rated current to
1.2 * rated current
Trip
time (s)
60
0.5
0
Trip current at 60 Hz
4–55
SJ300 Inverter
14 13 11
CM2
15 12
+
–
A
53.4 69 92
116% 150% 200%