Emerson 721NPBB Optional LVD Driver Circuit Card

User Instructions UM582127000
Spec. No. 582127000 (Model 721NPBB) Issue AC, January 2, 2013
Chapter 2. Operating Procedures Page 7
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Optional LVD Driver Circuit Card
The optional LVD driver circuit card installed in the main bay contains an LVD inhibit
switch and indicator. Refer to Figure 2-3. LVD driver circuit cards are required for 2-, 3-,
or 4-row distribution cabinets that contain three or more LVD contactors (LVBD and/or
LVLD); or if the distribution cabinet is equipped with an LVBD contactor rated 1200A or
higher.
Caution: If the switch is returned to the ON (normal) position when low voltage
disconnect alarms are active, a low voltage disconnection will occur.
Warning: While the LVD inhibit switch is in the OFF (inhibit) position, a low
voltage disconnection will not occur if battery or load voltage decreases
below the low voltage disconnect setpoint. For maximum battery
protection, this switch should NOT be left in the OFF (inhibit) position.
Figure 2-3
Optional LVD Driver Circuit Card
LVDInhibit Switch
MomentaryUP / Middle / Down
MomentaryUP Position: Closes all LVD Contactors (inhibit mode).
MiddlePosition : OFF (ACU+ DOES NOT control LVD’s) (inhibit mode).
DOWNP osition: ON (ACU+controls LVD’s).
LVDInhibit
ActiveIndi cator
Illuminates when the
lowvo ltage disconnect
circuit has been disabled
through the use of the
LVDInhibit switch.
J6 J5 J4
J3 J2 J1
J9
J7
S1
Note:The UP position will not close the LVBD contactor
ifthe battery is manually disconnected using the
ManualBattery Disconnect Switch.
Switchand indicator located
oncir cuitcar d installed in
Main Bayonly.