🔐 Eastron MID Meters - Getting The CT Ratio's Right?

Eastron SMART X96 vs SMARTconnect X835 CT Configuration Differences

Overview

A support case highlighted a common configuration issue where documentation for the Eastron SMARTconnect X835 was mistakenly used to configure an Eastron SMART X96-5E meter.
The two products have very similar user interfaces and setup menus, but the Current Transformer (CT) configuration is entered differently. Using the wrong method can result in current and power readings being significantly incorrect.

Symptoms

You may observe:

• Current readings significantly higher or lower than expected.

• Power and energy values that do not match reference instruments.

• Clamp meter measurements disagreeing with the meter display.

• Voltage readings appear correct, but current and power values are incorrect.

Before changing CT settings, always verify:

• CT orientation.

• CT secondary wiring.

• CT ratio markings on the CT.

• Correct phase association.

• No open-circuit CT secondary conditions.

Root Cause

The confusion arises because the two products require different CT configuration methods:

Warning: Although the menu structures appear almost identical, the value expected by the meter is different and on a MID Meter, once configured, this setting is then Locked🔒

SMART X96-5E Configuration

Correct Method

The SMART X96 requires:

• CT1 = Primary Current

• CT2 = Secondary Current (1A or 5A)

The manual states:

CT1 (Primary Current): 1-9999A
CT2 (Secondary Current): 1A or 5A

Example

For a 100/5A CT:

Do not enter the calculated ratio of 20.

This is also explicitly stated in the SMART X96-5E manual:

If 100/5A CT, CT1 should be set to 0100.

SMARTconnect X835 Configuration

Correct Method

The SMARTconnect X835 uses:

• CT2 = Secondary Current (1A or 5A)

• CT Rate = Calculated Ratio

The X835 manual instructs the user to:

1. Select CT secondary current.

2. Enter the CT rate value.

Example

For a 100/5A CT:

Calculated CT Ratio:

100 ÷ 5 = 20

Common Mistake

Scenario

CT installed:

100/5A

Installer enters:

CT Ratio = 20

into a SMART X96 meter.

Result

The X96 interprets the value as:

CT Primary = 20A
CT Secondary = 5A

instead of:

CT Primary = 100A
CT Secondary = 5A

This causes the scaling of current measurements to be incorrect and all related power and energy values will also be wrong.

Quick Reference

For CTs Rated 100/5A

For CTs Rated 400/5A

For CTs Rated 1000/5A

Recommended Verification Procedure

After configuring either meter:

1. Confirm CT orientation is correct.

2. Verify CT primary rating matches the installed CT label.

3. Check CT secondary setting is correct (1A or 5A).

4. Compare displayed current against a calibrated clamp meter.

5. Confirm power readings are reasonable for the measured current and voltage.

6. Verify imported energy increments at an expected rate.

Key Takeaway

SMART X96 meters require the CT primary current value to be entered directly, whereas SMARTconnect X835 meters require the calculated CT ratio.

Because the setup menus and displays are very similar, using the wrong manual can easily lead to incorrect scaling and misleading current, power, and energy measurements. Always verify the exact meter model before configuring CT settings.

PS: If you inadvertently set the CT Ratio wrong in a MID Compliant Meter, then the setting parameter locks once accepted and you will need an unlock code to change this setting again, so contact Forest Rock Support by emailing support@forestrock.co.uk for an Unlock Code.

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