Liebert LDM user manual Connecting a Current Transformer to the LIB Board

Installation

4.5Connecting a Current Transformer to the LIB Board

LIB can monitor eight 5-wire output/subfeed breakers. Two LIB boards are provided to support up to 16 output and/or subfeed breakers. If subfeed breakers are ordered with the unit, the phase CTs are installed and wired to the LIB. The neutral and ground CTs are also factory-supplied and wired to the LIB.

Since the CTs must be installed on the subfeed breaker’s neutral and ground cables, they cannot be installed in the factory. They are located in the bottom of the unit in front of the transformer.

CTs have an arrow, white dot or similar marking that depicts how to position the CT to ensure accu- rate readings. The arrow, white dot or similar marking must face the load when installing the CT on the ground and neutral cable. Route the neutral and ground cable through the core of the CTs and wire-tie the CT to the cable.

If subfeed breakers are installed in the field, up to five CTs may be installed to monitor a subfeed breaker (three phases, neutral and ground). The neutral and ground CTs may be omitted if monitor- ing of neutral and ground is not required.

The designators on the LIB are different from those on the PBVI board.

•CT1 (Phase A white wire) begins on TB1 CT1+ and the black wire connects to CT1-.

•The Ground CT for the first subfeed/output circuit breaker connects to TB4 CT35.

Four CTs	Ground CT
(three phases
and neutral)

Refer to the example below and Tables 3 and 4 for wiring configuration details.

Example: The above pictures show how to install CTs for a subfeed or I-Line output circuit breaker with neutral and ground being monitoring. The CTs should be wired as follows:

	First Breaker			Second Breaker
CT1+	Phase A CT	White wire	CT5+	Phase A CT	White wire
CT1-	Phase A CT	Black wire	CT5-	Phase A CT	Black wire
CT2+	Phase B CT	White wire	CT6+	Phase B CT	White wire
CT2-	Phase B CT	Black wire	CT6-	Phase B CT	Black wire
CT3+	Phase C CT	White wire	CT7+	Phase C CT	White wire
CT3-	Phase C CT	Black wire	CT7-	Phase C CT	Black wire
CT4+	Neutral CT	White wire	CT8+	Neutral CT	White wire
CT4-	Neutral CT	Black wire	CT8-	Neutral CT	Black wire
CT35+	Ground CT	White wire	CT36+	Ground CT	White wire
CT35-	Ground CT	Black wire	CT36-	Ground CT	Black wire

If more output or subfeed CTs need to be installed, continue in the same pattern shown above.

•Connect the Phase A CT for the second breaker on CT5 (white wire to CT5+, black to CT5-).

•Connect the Ground CT for the second breaker to CT36 (white wire to CT36+, black to CT36-).

•Continue the same pattern until all CT connections are used or there are no more output or sub- feed CTs to add.

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