Hitachi L100 instruction manual Electronic Thermal Overload Alarm Setting, Thm, Lvl

3–22

“B” Group: Fine Tuning Functions

Electronic Thermal Overload Alarm Setting

The thermal overload detection protects the inverter and motor from excessive heat. First use B13 to select the torque charac- teristic as a function of frequency. For example, a motor can overheat if it runs for too long at a low speed. You can counter- act this effect by reducing the torque at low speed. Otherwise, use the constant torque characteristic.

Torque	Constant torque			B13 = 01
100%
80%			Reduced
60%			torque
		B13 = 00
0	5	20	60	Hz
				120
			Output frequency

Configuring Drive Parameters

The torque developed in a motor is directly proportional to the current in the windings, which is also proportional to the heat generated (and temperature, over time). Therefore, you must set the thermal overload threshold in terms of current (amperes) for parameter B12. The range is 50% to 120% of the rated current for each model of inverter. If the current exceeds the level you specify, the inverter will trip and log an event (error E5) in the history table. The inverter turns the motor output off when tripped.

	“B” Function		Run-	Defaults		DOP,DRW,DOP+
Func.	Name	Description	time	EU/	Units	Func.	Name
			Edit
Code				US		Code
B12	Level of electronic	Set a level between 50% and	✘	rated	%	F-23	E-THM
	thermal setting	120% for the rated inverter		Amps			LVL
		current.		*Note
B13	Electronic thermal	Select from two curves, option	✘	01	A	F-23	E-THM
	characteristic	codes:					Char Sub
		00 ...(SUB) reduced torque
		01 ...(CRT) constant torque

NOTE: For inverter models 005NFE, 011NFE, and 030HFE, the thermal value is less than the rated amperes (is the same as models 004NFE, 007NFE, and 040HFE respec- tively). Therefore, be sure to set the electronic thermal overload according to the actual motor driven by the particular inverter.