How to Choose a 70mm Split Core Current Transformer for 1000A Current Measurement

Measuring AC currents up to 1000A requires more than simply selecting a current transformer with a 1000A rating. Engineers also need to consider conductor size, CT window diameter, secondary output, accuracy, installation method and the input requirements of the connected meter.

For applications involving large cables or retrofit installations, a 70mm split core current transformer can provide a practical solution because it can be installed around an existing conductor without disconnecting the primary circuit.

This guide explains the main factors to consider when selecting a 70mm split core CT for 1000A current measurement.

1. Why Use a Split Core CT for 1000A Current Measurement?

Traditional solid core current transformers require the conductor to pass through the CT during installation. In an existing electrical system, this may require disconnecting the cable.

A split core current transformer can be opened and installed around an existing conductor.

This makes split core CTs particularly suitable for:

• Retrofit energy monitoring

• Electrical distribution panels

• Energy meters and submeters

• Building energy management

• Industrial power monitoring

• Energy Management Systems (EMS)

For existing installations, the split core structure can significantly simplify installation.

2. When Is a 70mm Aperture Necessary?

The aperture, also called the window size or inner diameter, determines the maximum conductor size that can pass through the current transformer.

A 70mm aperture is useful when measuring current on large cables or conductors that cannot fit through smaller CT windows.

Before selecting a CT, always check the actual outside diameter of the conductor rather than selecting the CT only according to current rating.

For example, two systems carrying similar current may use cables with very different outside diameters.

Therefore:

Current rating determines the electrical measurement requirement.

Window size determines whether the CT can physically fit around the conductor.

Both specifications must be considered.

3. How to Select the Primary Current Rating

The CT primary current rating should be selected according to the expected operating current of the electrical system.

For high-current applications, common requirements may include:

• 400A

• 500A

• 600A

• 800A

• 1000A

A CT should not be selected only according to the maximum possible system current. Normal operating current and measurement range should also be considered.

For applications requiring different current ratings with the same large window size, the Jiangyin Spark XH-SCT-T70 series is available with primary current options from 100A to 1000A.

4. 1000A/5A vs 1000A/1A vs mA and mV Outputs

Choosing the correct secondary output is one of the most important steps when selecting a current transformer.

Different meters, monitoring devices and controllers require different CT inputs.

1000A/5A

A 5A secondary output is commonly used with equipment designed for conventional current transformer inputs.

If the connected meter requires a 5A CT input, a 1000A/5A configuration may be appropriate.

1000A/1A

A 1A secondary output can be used with meters and protection or monitoring equipment designed for a 1A CT input.

Always confirm the input specification of the connected device before selecting between 1A and 5A.

mA Output

Low-current secondary outputs are available for compatible electronic meters and current monitoring equipment.

The exact secondary current should match the input specification of the connected device.

mV Output

Voltage-output CTs, such as compatible mV configurations, can be connected to monitoring devices designed specifically for voltage-output current sensors.

Do not replace a current-output CT with a voltage-output CT unless the connected equipment supports that signal.

5. Can a 1000A CT Be Installed Without Disconnecting the Cable?

Yes, if a suitable split core current transformer is used.

The CT housing opens so that it can be placed around an existing conductor and then closed.

This is one of the main advantages of split core CTs for retrofit projects.

However, installers should still follow applicable electrical safety procedures and ensure that the CT is correctly closed and positioned according to the manufacturer's installation instructions.

6. 70mm Split Core CT vs Solid Core CT

Both split core and solid core current transformers can be used for current measurement, but their installation requirements are different.

A solid core CT can be suitable for new equipment where the conductor can be passed through the transformer during assembly.

A split core CT is generally more convenient when:

• The electrical system is already installed

• Disconnecting the conductor is difficult

• Retrofit monitoring is required

• Installation time needs to be reduced

• Large existing cables need to be measured

For these situations, a 70mm split core CT provides both a large window and convenient installation.

7. What Specifications Should You Confirm Before Ordering?

Before ordering a split core current transformer, provide the supplier with the following information:

1. Primary current, such as 500A, 800A or 1000A

2. Required secondary output, such as mA, mV, 1A or 5A

3. Conductor outside diameter

4. Required CT window size

5. System frequency

6. Accuracy requirement

7. Connected meter or monitoring device

8. Lead wire length

9. Certification requirements

Providing this information helps avoid selecting a CT that has the correct current rating but the wrong physical size or output signal.

8. XH-SCT-T70 70mm Split Core Current Transformer

Jiangyin Spark XH-SCT-T70 is designed for large-aperture AC current measurement applications.

Key specifications include:

• 70mm aperture

• 100A to 1000A primary current options

• mA output options

• mV output options

• 1A output

• 5A output

• 50/60Hz applications

• Split core installation

• UL and CE certified options

• Customized lead wires and output configurations

The 70mm window makes the XH-SCT-T70 suitable for large cables, while its split core structure allows installation around existing conductors.

9. How to Select the Correct XH-SCT-T70 Configuration

A simple selection process is:

Primary Current → Conductor Diameter → Output Signal → Accuracy → Certification → Lead Wire

For example, if an application has a maximum current of approximately 1000A, uses a conductor that fits within a 70mm window, and the connected meter requires a 5A CT input, a suitable 1000A/5A configuration can be considered.

If the meter instead requires a voltage-output current sensor, an appropriate mV-output configuration should be selected.

The connected equipment specification should always be confirmed before ordering.

Conclusion

Choosing a current transformer for 1000A measurement requires consideration of both electrical and mechanical requirements.

A 70mm split core current transformer can be a suitable solution when the application involves a large conductor and requires retrofit installation without disconnecting the primary cable.

The most important parameters to confirm are primary current, conductor diameter, CT window size, secondary output and the input requirements of the connected measurement equipment.

For applications from 100A to 1000A, Jiangyin Spark XH-SCT-T70 provides a 70mm split core design with multiple mA, mV, 1A and 5A output options.

For model selection, provide your primary current, conductor diameter, required output and connected meter specification.