CT Installation Guidelines

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Getting Started: Four Simple Guidelines for Successful Current Transformer Installation

This guide is for the solar energy professional who will install current transformers (CTs) with the Enphase

IQ Envoy™ or Envoy-S Metered™. Refer to the Envoy Installation and Operation Manual for complete installation

instructions and safety warnings.

How CTs Work

The IQ Envoy and the Envoy-S use readings from CTs to report measurement data for

energy production and energy consumption. When current transformers (CTs) are wrapped

around a live wire, the current going through the wire induces a current on the CT’s

secondary winding. The current on the secondary winding is proportional to the current on

the original circuit and is used for making measurements.

Polarity Correctness

CTs have a specific polarity, which is determined by the direction of the secondary winding. It is important to

maintain proper CT polarity in all installations, otherwise readings will be negative.

Guidelines

If your meter readings are incorrect, use these guidelines for troubleshooting.

1. CT wire leads must land on the correct

terminals on the Envoy.

IQ Envoy terminal

blocks.

Envoy-S terminal

blocks.

2. The Envoy-S power terminal A and Line 1

consumption and production CTs must be

fed by the same line (phases must match).

To verify using a voltmeter, measure

voltages between endpoints:!

• Power terminal A to Line 1 = 0V

• Power terminal A to Line 2 = 240V

3. To ensure correct polarity, CT arrows must

be pointing toward the loads.

• For production CTs, toward the loads,

away from the Solar PV.

• For consumption CTs, toward the

loads, away from the grid.

4. Meters must be enabled using the

Enphase Installer Toolkit™ mobile app to

report meter data to Enphase Enlighten™.

• Select the consumption meter type

based on where you installed the

consumption CTs.

• Enable both the production and

consumption meter.

Secondary Winding

View of Internal Winding

Not Used

IQ#Envoy

Envoy

Example

Envoy-S

Summary of content (1 pages)

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Getting Started: Four Simple Guidelines for Successful Current Transformer Installation This guide is for the solar energy professional who will install current transformers (CTs) with the Enphase IQ Envoy™ or Envoy-S Metered™. Refer to the Envoy Installation and Operation Manual for complete installation instructions and safety warnings. Secondary Winding How CTs Work The IQ Envoy and the Envoy-S use readings from CTs to report measurement data for energy production and energy consumption.