Program features 135
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:
1. The motor is in the ambient temperature of 30 °C when power is applied to the
drive.
2. 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 in case the ambient temperature
exceeds 30 °C.
Settings
Parameters 3005 MOT THERM PROT…3009 BREAK POINT FREQ
Note: It is also possible to use the motor temperature measurement function. See
section Motor temperature measurement through the standard I/O on page 145.
Earth fault protection
The Earth fault protection detects earth faults in the motor or motor cable. The
protection is active only during start.
An earth fault in the input power line does not activate the protection.
Settings
Parameter 3017 EARTH FAULT
Incorrect wiring
Defines the operation when incorrect input power cable connection is detected.
}
Motor
load
Temp.
rise
100%
63%
Motor thermal time constant
t
100 =
127%
150
50
P 3007
P 3008
f
Output current relative (%) to
motor nom. current
P 3009
100%
Break point
Motor load curve
Zero speed load
t
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