Schneider Electric HRB1684301-01 Control power wiring, Communications, Neutral and ground current

PowerLogic™ PM5500 series user manual Chapter 2—Hardware reference

Balanced 3-phase Wye system with 2 CTs

The current for the unconnected current input is calculated so that the vector sum for all three phase currents equal zero.

Balanced 3-phase Wye or Delta system with 1 CT

The currents for the unconnected current inputs are calculated so that their magnitude and phase angle are identical and equally distributed, and the vector sum for all three phase currents equal zero.

NOTE: You must always use 3 CTs for 3-phase 4-wire center-tapped Delta or center-tapped open Delta systems.

Neutral and ground current

The fourth current input (I4) can be used to measure current flow (In) in the neutral conductor, which can then be used to calculate residual current. The meter refers to residual current as ground current (Ig).

For 4-wire Wye systems, ground current is calculated as the difference between the measured neutral current and the vector sum of all measured phase currents.

Control power wiring

For wiring instructions and safety precautions, see the meter installation sheet that was shipped with your meter, or download a copy at www.schneider-electric.com.

The meter can be powered from an AC or DC power source.

•L1 and L2 are non-polarized. If using an AC power supply with neutral, connect neutral to the meter’s L2 terminal.

•Always use a fuse on L1. Fuse L2 when connecting an ungrounded neutral to the control power.

•If using a control power transformer, fuse both primary and secondary sides of the transformer.

•The fuses / circuit breakers must be rated for the installation voltage and sized for the available fault current.

Communications

This section provides additional information about the communications ports and topologies supported by the meter. You must wire and configure the RS-485 port and/or the Ethernet port in order to communicate with the meter.

Serial communications

The meter supports serial communications through the RS-485 port. Up to 32 devices can be connected on a single RS-485 bus.

In an RS-485 network, there is one master device, typically an Ethernet to RS-485 gateway. It provides the means for RS-485 communications with multiple slave devices (for example, meters). For applications that require only one dedicated computer to communicate with the slave devices, an RS-232 to RS-485 converter can be used as the master device.

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