ABB ACS560, Firmware Manual

Page: 89 / 514

Program features 89
Motor overload protection requires that you specify a motor current tripping level. This
is defined by a curve using parameters
35.51 , 35.52 and 35.53 . The tripping level is
the motor current at which the overload protection will ultimately trip if the motor
current remains at this level continuously.
The motor overload class (class of operation), parameter 35.57 Motor overload class ,
is given as the time required for the overload relay to trip when operating at 7.2 times
the tripping level in the case of IEC 60947-4-1 and 6 times the tripping level in the
case of NEMA ICS 2. The standards also specify the time to trip for current levels
between the tripping level and the 6 times tripping level. The drive satisfies the IEC
standard and NEMA standard trip times.
Using class 20 satisfies the UL 508C requirements.
The motor overload algorithm monitors the squared ratio (motor current / tripping
level)2 and accumulates this over time. This is sometimes to as I2t protection. The
accumulated value is shown with parameter
35.05 .
You can define with parameter 35.56 that when 35.05 reaches 88%, a motor overload
warning will be generated, and when it reaches 100%, the drive will trip on the motor
overload fault. The rate at which this internal value is increased depends on the
actual current, tripping level current and overload class selected.
Parameters 35.51 , 35.52 and 35.53 serve a dual purpose. They determine the load
curve for temperature estimate as well as specify the overload tripping level.
Settings and diagnostics
Parameters common to motor thermal protection and motor overload protection:
35.51 Motor load curve ... 35.53 Break point (page 288 ).
Parameters specific to motor overload protection: 35.05 Motor overload level (page
280 ), 35.56 Motor overload action ... 35.57 Motor overload class (page 290 ).
Events: A783 Motor overload (page 417 ) and 7122 Motor overload (page 431 ).
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Programmable protection functions
External events (parameters 31.01 … 31.10 )
Five different event signals from the process can be connected to selectable inputs to
generate trips and warnings for the driven equipment. When the signal is lost, an
external event (fault, warning, or a mere log entry) is generated.
Motor phase loss detection (parameter 31.19 )
The parameter selects how the drive reacts whenever a motor phase loss is detected.
The motor phase loss detection is enabled by default and displays fault 3381 Output
phase loss whenever the drive detects a phase loss. The motor phase loss detection