System Operation
Copyright © 2007-2018 Eaton Corporation. All Rights Reserved.
IPN 997-00012-03 B2 Issue B2 July 2018
47
Low Voltage Disconnect (LVD)
Low Voltage Disconnects may be connected either as load disconnect or battery disconnect
depending on the dc power system model. They have two purposes:
•
to protect a VRLA battery from deep discharge and premature failure, and/or
•
to reduce the load on a battery under discharge so that high priority equipment operates for a
longer time after an ac supply failure.
The SC300 has 16 independent LVD control channels (LVD 1 to LVD 16). Each channel can control
one or more of up to 16 contactors, with coil voltages from 12V to 48V nominal.
There are two contactor connectors on an IOBGP-00/01 Input / Output board, and three on the
IOBGP-10/11. Additional contactors are controlled by additional IOBGP-01 Input / Output
boards. If required, refer to the dc power system Installation and Operation Guide for details on
how to connect additional IOBGP-01 Input / Output boards to the SC300.
Latched contactors
The IOBGP-10/11/20/21 IO Boards support latched contactors. Latched contactor operation is
managed by the IOBGP and does not affect SC300 operation or settings.
Use
Normally Open
settings for latched contactors.
LVD Disconnect Modes
The LVD control channels can have any combination of the following modes of operation:
1
Voltage Based Disconnect
: The LVD control channel will disconnect its contactor(s) based on
the bus voltage.
2
AC Timer Based Disconnect
: The LVD control channel will disconnect its contactor(s) after a
specified period of ac supply failure.
3
Smart Alarm Disconnect
: The LVD control channel will disconnect its contactor(s) according
to the state of a specified
Smart Alarm
. See
Smart Alarm Disconnect
on page 53.
If
Chained to Previous
is enabled, the LVD control channel will only disconnect its contactor(s) if one
of its disconnect conditions is
True
, and the preceding control channel has been disconnected for
the
Recognition Time
.
Chained to Previous does not apply to LVD 1.
LVD Default and Custom Configuration
If factory-fitted in the dc power system, the LVD contactors will be characterized and the LVD
control channels will have default configuration settings for
Voltage Based Disconnect
. Custom
configuration will only be necessary if:
•
contactors are connected to the dc power system on site (see LVD Characterization on page 49
and LVD Setup on page 50)
•
different disconnect conditions are required (see LVD Configuration on page 52).