Alpha Technologies CXPS 48-1.2-225 48 Vdc - Manual (Page 19)

053-691-B1 Rev E Page 11 of 33
2.5.4 True module fail alarm
The rectifier modules use a “true” fail alarm. This provides a true indication of the module’s ability to source
current. When a module’s output current drops below 2.5% of the rated output, a low output current condition is
detected and the Module Fail detection circuit is activated. This circuit momentarily ramps up the output voltage in
an attempt to increase the output current. If no increase in current is detected, the Module Fail alarm is activated.
When the Module Fail alarm is activated, the rectifier will check the output current once every 60 seconds until the
current is within the rated output. Output voltage ramping will then cease when the current reaches the rated
range. Under normal conditions, a battery that is connected to the rectifier output will draw current during a
voltage ramp up. A rectifier fail alarm will therefore not be generated when a battery is connected.
A minimum 2.5% load current is required to avoid a module fail alarm; but a bank of parallel batteries will typically
draw this much current. Activation of this alarm could indicate a failed rectifier module or a failed load.
To avoid nuisance alarms, disable the Ramp Test feature for rectifier systems without batteries or with a load;
below 2.5% of the rated output. Use the menu on the controller to enable/disable the Ramp Test. On the menu,
go to "Rectifiers", then "Configure Settings".
2.5.5 Heat dissipation
Each rectifier module is cooled by a variable-speed fan. The speed of the fan is governed by a temperature
sensor on the heat sink. The cooling air enters the front of the module and exits the rear of the module.
2.5.6 Over-temperature protection
Each rectifier module is protected against an excessive increase in temperature caused by a component failure or
blockage of the cooling air. During an over-temperature condition, the rectifier limits the output power and the
output current. If the temperature continues to increase, a shutdown of the rectifier is initiated. The rectifier
restarts automatically when the temperature returns to a safe level.
2.5.7 Wide AC input power range
A minor alarm is activated when the AC input voltage drops below a specified value. The output power is reduced
linearly between 176 Vac and 132 Vac to 60% of the rated output power. The input current is limited to less than
6 A for operation between 132 Vac and 90 Vac. A constant output power of 600 W is available between 132 Vac
and 112 Vac. The output power is derated linearly from 600W to ~475W @ 90Vac. At lower voltages, the module
will shut down and will not restart until the AC input voltage is greater than 90 Vac.
For input voltages above 277 Vac, the power factor and total harmonic distortion may be derated. The rectifier
may not work if the input voltage is above 320 Vac, but will not suffer any damage.
2.5.8 AC inrush/transient suppression
The inrush current into the rectifier module is limited to the full load steady state line current to prevent a current
surge on the AC input line. The modules are protected from input lightning and transient surges in accordance
with IEEE/ANSI C62.41 Category B3 standards.