ABB ACS880 Series, Firmware Manual

Page: 128 / 764

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Motor thermal protection
The control program features two separate motor temperature monitoring
functions. The temperature data sources and warning/trip limits can be set up
independently for each function.
The motor temperature can be monitored using
• the motor thermal protection model (estimated temperature derived internally
inside the drive), or
• sensors installed in the windings. This will result in a more accurate motor
model.
WARNING! Double or reinforced insulation is required between the live
parts of the motor and the drive control unit. See the hardware manual
for more information.
In addition to temperature monitoring, a protection function is available for ‘Ex’
motors installed in a potentially explosive atmosphere.
Motor thermal protection model
The drive calculates the temperature of the motor on the basis of the following
assumptions:
1. When power is applied to the drive for the first time, the motor is assumed to
be at ambient temperature (defined by parameter
35.50 ). After this, when
power is applied to the drive, the motor is assumed to be at the estimated
temperature.
2. Motor temperature is calculated using the user-adjustable motor thermal time
and motor load curve. The load curve should be adjusted in case the ambient
temperature exceeds 30 °C.
The motor thermal protection model fulfills standard IEC/EN 61800-5-1 ed. 2.1
requirements for thermal memory retention and speed sensitivity. The estimated
temperature is retained over power down. Speed dependency is set by parameters
35.51 , 35.52 and 35.53 .
Note: The motor thermal model can be used when only one motor is connected
to the drive.
Temperature monitoring using PTC sensors
One PTC sensor can be connected to digital input DI6.
128 Program features