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If the rectifier output voltage exceeds the HVSD level, the rectifier will turn off within about 100
ms. Since the voltage is measured on the “inside” of the blocking diode, the HVSD function is
selective, i.e. only the module that is responsible for the overvoltage will trip. Initially, the
ALARM-lamp turns on and the ON-lamp will start to flash slowly. With an interval of five
seconds, three restart attempts will be performed. If also the third attempt fails, the module will
be turned off for good while both the ON- and STBY-lamps are turned off and the ALARM-
lamp continues to shine.
Restart after tripped HVSD can be done by keeping the ON-button pressed for at least 5
seconds or by turning off the AC power for a short while. You can also put the module in
standby mode by keeping the STBY-button pressed for at least 5 seconds.
4.2.10
Over-/Undervoltage AC
The rectifier module has a built-in self protection that will stop the module when exceeding
harmful high or low voltages on the AC power feeding. For trip levels, see section 3.2.1. The
module will go back to normal operation as soon as the voltage returns within permissible
limits.
4.2.11
External blocking
The rectifier modules can also be turned off remotely via a digital input found on the
monitoring unit. The function is called “External blocking”. The output voltage will be turned
off, the ON-lamp will flash slowly and the STBY-lamp is off. When the blocking condition
ceases, the module returns to normal operation.
Even during blocking condition, the module can be turned off “for real” using the STBY-button.
In this way the module will remain off when the blocking condition ceases.
4.2.12
Hot swap
Connection of a rectifier module to a DC system during operation (hot swap) is normally not
entirely straightforward. Without certain measures you will get a heavy inrush current due to
charging of capacitors on the rectifier DC output. Except sparking at the point of connection,
you may get a short system voltage drop with possible consequences.
With PRM3, this problem is eliminated due to a built-in output diode that prevents charging of
the capacitors from the outside. An extra advantage with the diode is that it eliminates the risk
of sinking the whole DC system due to an internal module fault (short circuit). PRM3 modules
may consequently without problem be replaced during operation which to a great extent
simplifies maintenance and service and will also extend the availability of the DC system.
4.3
FUNCTIONS OF COMPLETE CHARGING RECTIFIER
4.3.1
General
A complete rectifier system of the type PRX3 may, depending on model, hold up to 6 rectifier
modules in parallel of the type PRM3.
Here, only the most considerable functions are described. For more information, see
Manual for
monitoring unit PCM2
.
