Operation
58
Atlas
®
Digital Amplifier Complete Technical Reference
4
• Re-enable the current loop and power stage modules using the
RestoreOperatingMode
command.
If the overcurrent condition has been resolved, at the end of this sequence Atlas will resume normal operations. If the
overcurrent condition has not been resolved, the overcurrent condition will immediately occur again, and the recovery
sequence described above must be undertaken again.
4.8.2
Overtemperature Fault
Atlas provides the capability to continually monitor and detect excessive internal temperature conditions. Such a
condition may occur if excessive current is requested, if heat sinking of the Atlas unit is inadequate, or if some other
problem results in elevated drive temperatures.
To detect this condition a programmable temperature threshold is continuously compared to an internal temperature
sensor. If the value read from the internal sensor exceeds the programmed threshold, an overtemperature fault occurs.
In addition, a settable overtemperature hysteresis allows the user to ensure that the Atlas temperature drops by a
specified number of degrees before allowing drive restart.
To set the programmable temperature threshold or the programmable temperature hysteresis the command
SetDriveFaultParameter
is used. To read back these values the command
GetDriveFaultParameter
is used.
The maximum allowed setting for the temperature threshold is 75.0° C, which is also the default value. The value set
using the
SetDriveFaultParameter
command is in units of degrees C/256. For example, a value of 12,800 sets a
threshold of 50° C. The maximum allowed value of the hysteresis parameter is 50° C, and the default value is 5° C.
An over temperature fault will cause the following events to occur:
• The current loop and power stage modules are disabled, thereby halting further motor output.
• The Drive Fault Status register records an overtemperature fault condition.
• The Event Status register records a drive exception condition.
To recover from this condition the user should determine the nature of the fault using the
GetDriveFaultStatus
command. It may be desirable to power down Atlas to correct the condition.
If the condition is resolved but Atlas is not power cycled, the following sequence should be used to restore the drive
to normal operation:
• Clear the fault condition using the
ClearDriveFaultStatus
command.
• Clear the drive exception bit of the Event Status word using the
ResetEventStatus
command. It is not
possible to re-enable the current loop or the power stage module if the drive exception bit is still active.
• Re-enable the current loop and power stage modules using the
RestoreOperatingMode
command.
If the overtemperature condition has been resolved, at the end of this sequence Atlas will resume normal operations.
If the overtemperature condition has not been resolved, the condition will immediately occur again, and the sequence
described above should be undertaken again.
The instantaneous status of the overtemperature threshold comparison can be read using the command
GetDriveStatus
.
Over current faults are serious conditions and warrant the utmost precaution before re-enabling amplifier oper-
ation. It is the responsibility of the user to determine the cause and corrective action of any electrical fault.
