Operation
Atlas® Digital Amplifier Complete Technical Reference
59
4
To read the current value of the temperature sensor the command
GetTemperature
is used.
4.8.3
Overvoltage Fault
Atlas provides the capability to continually monitor and detect excessive voltages on the incoming voltage supply. Such
a condition may occur if there is a fault in the system power supply, if a large back EMF (electro motive force) is
generated during motor deceleration, or if some other problem results in an elevated bus voltage.
To detect this condition a programmable bus voltage threshold is continuously compared to the bus voltage sensor.
If the value read from the internal sensor exceeds the programmed threshold, an overvoltage fault occurs.
To read the current value of the bus voltage the command
GetBusVoltage
is used.
To set the programmable overvoltage threshold the command
SetDriveFaultParameter
is used. To read back this
value the command
GetDriveFaultParameter
is used.
The maximum allowed setting for the overvoltage threshold is either 52.0 or 60.0 volts depending on the Atlas unit
used. The minimum allowed threshold is 10.0 volts. The value set using the
SetDriveFaultParameter
command is
in units of 1.361 mV/count. For example, a value of 14,695 sets a threshold of 14,695 * 1.361 mV/count = 20.00 volts.
See
Section 3.11.1, “Atlas Settings Defaults and Limits”
for a complete list of Atlas limits and default temperature
settings.
An overvoltage 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 overvoltage 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. In most cases it is 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 overvoltage condition has been resolved, at the end of this sequence Atlas will resume normal operations. If the
overvoltage condition has not been resolved, the condition will immediately occur again, and the sequence described
above should be undertaken again.
Overtemperature faults indicate that the internal safe limit of the drive temperature range has been exceeded.
This potentially serious condition can result from incorrect motor connections, excessive power demands placed
on the Atlas amplifier, or inadequate heat sinking. It is the responsibility of the user to operate Atlas within safe
limits.
