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2.0 PRODUCT OVERVIEW
The Liebert Distribution Monitor (LDM) monitors the main panelboard circuit breaker and individual
panelboard branch circuit breakers. The measurements are used to report the current and alarm con-
ditions for each breaker. The Liebert LDM utilizes branch circuit sensor modules and individual cur-
rent transformers (CT) to monitor current. In addition, the Liebert LDM monitors options like
subfeed and output circuit breakers and provides a full array of power parameters and alarms.
The Liebert LDM is available as an option for the Liebert PPC™ Precision Power Center, Liebert
FDC™, Liebert FPC™ and Liebert RDC™ Remote Distribution Cabinet.
The Liebert LDM system can communicate with a Building Management System (BMS) and Liebert
SiteScan
®
Web.
The Liebert LDM consists of a control board, panelboard voltage and current board, power supply
boards and sensor modules and can monitor two 42-pole panelboards and three subfeed breakers.
The Liebert LDM is capable of receiving input from 21-pole current sensor modules; two sensor mod-
ules are required to monitor one 42-pole panelboard. The sensor module (BSM) contains twenty-one
50A current transformers (CTs) capsulated in an epoxy-filled plastic enclosure designed to be
mounted next to the panelboard. Sensor modules are designed to work with Square D™ and GE pan-
elboards. If a sensor module CT fails, connections are provided for up to six replacement CTs. The
optional CTs can be attached directly to the load cable feeding the failed CT.
For branch breakers larger than 50A, discrete 100A rated large branch current transformers can be
added. Higher-rated CTs can be used for monitoring optional subfeed circuit breakers. For subfeed
breakers, like main panelboard breakers, the Liebert LDM monitors not only the 3-phase current but
also the ground and neutral current. These subfeed circuit breakers are in addition to the 42 panel-
board circuit breakers that can be monitored through the BSM. The Liebert LDM can accommodate
18 individual large current transformers.
If your Liebert power center is supplied with a Square D I-Line
®
panelboard, the Liebert LDM can
also monitor it as well as its output breakers. A large interface board (LIB) replaces the panelboard
voltage and current board and can monitor up to 42 poles. Each LIB can monitor eight 5-wire I-Line
and/or subfeed breakers including ground and neutral current. There can be 1 or 2 LIBs per control
board that can monitor a total of sixteen 5-wire I-Line and/or subfeed breakers.
The Liebert LDM has a Modbus port on the BCB for direct communication with a building manage-
ment system (BMS). The Liebert LDM can communicate with Liebert SiteScan by using a Liebert
SiteLink™ communication device. A Liebert SiteLink-2E™ is available as an option with the Liebert
LDM and is mounted in the power center. Modbus Registry Summary documentation can be found at:
http://www.liebert.com/product_pages/ProductDocumentation.aspx?id=72
Click on the link for the Liebert Distribution Monitor (LDM Toolkit). Save the file to a desktop or lap-
top computer (PC) and extract the contents.