Hitachi SJ300 Series Overload Restriction, Set, Set, Opt, Code, Input, Symbol, Function, Required, settings:, Description, Description, Function Code, Data or Range

4–35

SJ300 Inverter

Overload Restriction

The inverter constantly monitors the motor current during acceleration, deceleration, and constant speed. If the inverter reaches the overload restriction level, it adjusts the output frequency automatically to limit the amount of overload. This function prevents an over-current trip by inertia during rapid acceleration or large changes in load at constant speed. It also attempts to prevent an over-voltage trip on deceleration due to regeneration. It accomplishes this by temporarily suspending deceleration and/or increasing the frequency in order to dissipate regenerative energy. Once the DC bus voltage falls sufficiently, deceleration will resume.

OLR Parameter Selection – Two sets of overload restriction parameter settings and values are available as outlined in the table below. Use the B021—B026 group of settings to configure the two set of parameters as needed. By assigning the Overload Restriction function [OLR] to an intelligent terminal, you can select the set of restriction parameters that is in effect.

Function	Function Code		Data or Range	Description
	Set 1	Set 2
Overload Restriction	B021	B024	00	Disable
Operation Mode
			01	Enabled during accel
				and constant speed
			02	Enabled during constant
				speed
			03	Enabled during accel,
				constant speed, and
				decel
Overload Restriction	B022	B025	Rated current * 0.5	Current value at which
Setting			to rated current * 2	the restriction begins
Deceleration Rate at	B023	B026	0.1 to 30 seconds	Deceleration time when
Overload Restriction				overload restriction
				operates

Opt.

Symbol

Function Name

Input

Description

Code

State

39

OLR

Overload Restric-

ON

Selects Overload Restriction Set 2,

tion Selection

B024, B025, B026 settings in effect

OFF

Selects Overload Restriction Set 1,

B021, B022, B023 settings in effect

Valid for inputs:

C001, C002, C003, C004,

Example: (Requires input configuration—

C005, C006, C007, C008

see page 3–47. Jumper position shown is

for –xFU/-xFR models; for –xFE models,

Required

B021, B022, B023 (Mode 1),

see page 4–12.)

settings:

B024, B025, B026 (Mode 2)

OLR

Notes:

TH

FW

8

CM1

5

3

1

• If the overload restriction constant (B023 or

P24

PLC

CM1

7

6

4

2

B026) is set too short, an over-voltage trip

during deceleration will occur due to regener-

ative energy from the motor.

• When an overload restriction occurs during

acceleration, the motor will take longer to

reach the target frequency, or may not reach

it. The inverter will make the following

See I/O specs on page 4–9.

adjustments:

a)Increase the acceleration time

b)Raise torque boost

c)Raise overload restriction level

Operations Monitoring and