Hitachi SJ300 Series outputs:, Required, Valid for, settings:, Thermal Warning Output

4–57

SJ300 Inverter

The left graph below shows the region for possible free-setting curves. The right graph below shows an example curve defined by three data points specified by B015 – B020.

Trip current				Output
reduction
				current (A)
factor
x 1.0
					B020
x 0.8	Setting range				B018
					B016						Hz
0				Hz	0
5		Output freq.	400			B015	B017	B019	Ax04	max. freq.

Suppose the electronic thermal setting (B012) is set to 44 Amperes. The graph below shows the effect of the free setting torque characteristic curve. For example, at (B017) Hz, the output current level to cause overheating in a fixed time period is reduced to (B018) A. Points (x), (y), and (z) show the adjusted trip current levels in those conditions for given trip times.

Trip

time (s)

60				(x) = B018 value x 116%
				(y) = B018 value x 120%
0.5				(z) = B018 value x 150%
0			A	Reduced trip current at (B017) Hz
	(x) (y)
		(z)

Thermal Warning Output – Using parameter C061, you can set the threshold from 0 to 100% of trip level for turning ON the intelligent output [THM] at that level. In this way, the inverter provides an early warning before the electronic thermal overload trips and turns OFF the output to the motor.

Operations Monitoring and

Opt.

Symbol

Function Name

Output

Description

Code

State

13

THM

Thermal Warning

ON

when the electronic thermal calculation

exceeds the set limit

OFF

when the electronic thermal calculation is

less than the set limit

Valid for

11, 12, 13, 14, 15,

Example: (Requires output configuration—

outputs:

AL0 – AL2

see page 3–53.)

Required

C061

Inverter output

settings:

terminal circuit

THM

Notes:

• The electronic thermal overload function uses

14

13

11

the output current and time to calculate

See I/O specs

15

CM2

12

thermal heating of the motor.

on page 4–9.

•The thermistor input of the inverter is a separate function from the electronic thermal

function. You can set a threshold for it to
cause a trip alarm at a particular thermistor
	RY	+
resistance.		–