Hitachi EN013001-1 User's Guide

EN-013001-1

Hitachi America, Ltd.

ENGINEERING NOTE

SUBJECT: OVERLOAD RESTRICTION FUNCTION (B21, B22, B23)

AFFECTED UNITS: L100, SJ100, L300P, SJ300

Problem

In some instances with high inertia loads, the factory default settings of the Overload
Restriction function may result in nuisance Overvoltage (E07) trips.

Discussion

Refer to the Overload Restriction Function description in the Instruction Manual for the
inverter. This function is designed to avert an overload trip by detecting excessive load
current, and reducing the output frequency in an attempt to make the load current
decrease before a trip occurs. When the current drops below the threshold, the function
turns off, and normal inverter operation resumes. Sometimes, when the load has high
inertia, this has the side-effect of causing excessive regenerative energy to flow back to
the inverter, causing instead an E07 Overvoltage Trip.

Parameters B22 and B23 control the action of this function. B22 controls the current
threshold level at which the restriction function is triggered, and B23 sets the
deceleration rate the function uses (different from the deceleration rate the inverter uses
for normal operation, set by parameter F3). The following are default settings by model:

Model
Series

L100 1.25 x rated current 1.0 sec
SJ100 1.25 x rated current 1.0 sec
L300P 1.20 x rated current 1.0 sec
SJ300 1.50 x rated current 1.0 sec

Corrective Action If this problem occurs, try gradually DECREASING the setting of B22, and INCREASING the setting of B23, and see it the trip occurrence is reduced or eliminate.

This has the effect of activating the Overload Restriction Function sooner, and making
the deceleration slower, reducing the possibility of the high inertia causing excessive
regeneration, and thus avoiding an E07 trip.

B22 Default Setting

(Current Threshold)

B23 Default Setting
(Deceleration Rate)

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