The NEX NEM91 and NEX NEM93 (Previously SPM91 and SPM93) power meters are one phase and three phase power meters respectively. They have solid core CTs, and so require slightly more installation time and preparation as opposed to the NEM20.

The 91 signals a single phase power meter, whilst the 93 signals a three phase power meter.

Installation

There are three components that are required to be wired in:

Single phase or three phase voltage

Depending on your model, you will need to wire in either one phase and neutral, or three phases and neutral. These should be wired in at the point you would like to monitor.

Communication bus

The Modbus data positive, data negative, and neutral lines should be wired into the NEM91 and NEM93.

Current Transformers (CTs)

Communication

The NEM91 and NEM93 support a Baud Rate of 9600. Simply set the Modbus address to the setting the NEX expects it to be on. One thing to note - the three phase meter's communications will not function when only a single phase has been wired in. Always completely wire in the NEM93 before attempting communication with it.

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