Motor Thermal Protection - ABB ACS355 series User Manual

148 Program features
Settings
Parameters 3010 STALL
TIME


Motor thermal protection

The motor can be protected against overheating by activating the Motor thermal
protection function.
The drive calculates the temperature of the motor on the basis of the following
assumptions:
• The motor is in the ambient temperature of 30 °C (86 °F) when power is applied to
the drive.
• Motor temperature is calculated using either the user-adjustable or automatically
calculated motor thermal time constant and motor load curve (see the figures
below). The load curve should be adjusted if the ambient temperature exceeds
30 °C (86 °F).
Motor
load
100%
Temp.
rise
100%
63%
Motor thermal time constant
Settings
Parameters 3005 MOT THERM
CURVE, 3008 ZERO SPEED LOAD
Note: It is also possible to use the motor temperature measurement function. See
section Motor temperature measurement through the standard I/O

Underload protection
Loss of motor load may indicate a process malfunction. The drive provides an
underload function to protect the machinery and process in such a serious fault
condition. Supervision limits - underload curve and underload time - can be specified
as well as the action taken by the drive upon the underload condition (alarm
indication / fault indication & drive stop / no reaction).
FUNCTION, 3011 STALL FREQUENCY
t
P 3007
P 3008
t
PROT, 3006 MOT THERM
and 3009 BREAK POINT FREQ
Output current relative (%) to
nominal motor current
150
Break point
100 =
127%
50
Zero speed load
P
TIME,
and 3012 STALL
Motor load curve
f
3009
3007 MOT LOAD
on page 157.