Safety And Protections; Fixed/Standard Protections; Motor Thermal Protection - ABB ACQ80-04 Firmware Manual

44 Program features
Example 2: If the reference switching frequency is set to 12 kHz and the minimum
switching frequency is set to the smallest available value, the drive maintains the
highest possible switching frequency to reduce motor noise and only when the drive
heats it will decrease the switching frequency. This is useful, for example, in
applications where low noise is necessary but higher noise can be tolerated when the
full output current is needed.
Settings
Parameter 97.01 Switching frequency reference
frequency (page 162).

Safety and protections



Fixed/standard protections

Overcurrent
If the output current exceeds the internal overcurrent limit, the IGBTs are shut down
immediately to protect the drive.
Drive temperature
If the temperature rises high enough, the drive first starts to limit the switching
frequency and then the current to protect itself. If it is still keeps heating up, for
example because of a fan failure, an overtemperature fault is generated.
Short circuit
In case of a short circuit, the IGBTs are shut down immediately to protect the drive.


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.
Motor thermal protection model
The drive calculates the temperature of the motor on the basis of 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
and 97.02 Minimum switching
35.50 Motor ambient temperature).