Lucent Technologies Lineage 2000 ECS-12U - Selective High Voltage Shutdown

Lucent Technologies Lineage
®
2000 ECS-12U Controller J85501E-2
Issue 3 July 1998 Product Description 2 - 7
The actual BD threshold settings that may be selected are listed
on Figure 4-5 and on a label on the controller itself. The range of
available settings is based on the most common battery float
voltages for 24V and 48V systems. The shutdown level can be
adjusted in 0.5 volt increments.
Selective High
Voltage
Shutdown
The controller is equipped to detect a high voltage condition on
the plant bus. Such a high voltage condition is typically caused
by lightning-induced transients on the commercial ac power
lines. A rectifier failure might, however, cause an individual
rectifier to increase its output voltage. To prevent high voltage
from damaging the connected telecommunications load, the
controller will send a signal for the rectifiers to shut down if the
plant voltage goes high.
When the controller detects an increase in the plant voltage
above a preset threshold, it immediately issues an HV alarm to
the external alarm system. HV is considered a Major alarm, so
all Power Major alarm groups are also issued.
If the rectifiers do not have load sharing, the controller sends a
simultaneous shutdown signal to all rectifiers while reporting the
alarm. Since the output of all rectifiers are paralleled in the plant,
their output voltages are forced to be the same. Their output
currents, however, may vary widely. In a high voltage condition
caused by an individual rectifier failure, the failed rectifier will
be supplying more current than any other rectifier. When the
high voltage shutdown signal is sent by the controller, any
Lucent Technologies rectifier supplying more than 10% of its
rating, i.e., the failed rectifier, will shut down, causing the plant
voltage to drop to normal and the HV alarm to retire. All other
rectifiers will remain on. If a high voltage condition exists
without an individual rectifier failure, e.g., because of incorrect
setting of the HV-threshold DIP switches or lightning-induced
high voltage, all Lucent Technologies rectifiers supplying more
than 10% of their rated current will shut down. The detection of
the high voltage condition and sending of the shutdown signal
are functions of the controller, while the selection of the
rectifier(s) with more than 10% rated current for shutdown is a
function of the rectifiers.
If the rectifiers have load sharing, the HV shutdown may operate
differently. In the Lucent Technologies SR series, if a single
rectifier fails, its output current will try to increase and the HV
signal will shut down only that rectifier. If the entire bus goes