User Manual

PSU -48 V Power Supply Unit
Table 3 PSU Alarms
Type of alarm
Description
Overvoltage failure The output voltage of the converter
has ex
ceeded the alarm level.
High temperature The internal temperature of the
converter has exceeded the set
value.
Converter not adjustable The converter output voltage cannot
be adjusted from a superior unit.
High output power The converter limits the power.
Input failure A failure has been detected in the
incoming DC supply.
Communication failure Signals from optical loop are not
received.
Converter failure Converter failures other than those
specified above have been detected.
4.3 Load Sharing
Load sharing is achieved by passive load sharing when using more than one
PSU. Passive load sharing exploits static regulations.
4.4 Output Overvoltage Protection
The PSU has two overvoltage monitors for the output voltage. The first
overvoltage level is factory set at 29.0 V. The other overvoltage monitor
(30.0 V) is determined from active and passive components. When one of the
overvoltage monitors is activated, the PSU will be shut down and one attempt
to restart is performed.
4.5 Power Limitations
When the temperature exceeds the permissable temperature, the PSU reduces
the power and an alarm is sent to the ECU. The output power is raised when
the temperature drops, and the alarm is reset. When the output power of the
rectifier reaches 700 W, the rectifier limits its power by reducing its ouput
voltage in order to maintain a constant output power. The ouput current
increases to a maximum of 32 – 34 A even in the event of short circuits. The
picture below shows the typical pattern at 32 A.
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EN/LZT 720 0281 Uen R1A