Why have single phase satuation current transformers (CTs) become an essential core component of switchgear in Southeast Asia?

— Detailed technical analysis using the ICT series encapsulated transformer as an example. We examine the ICT series encapsulated transformer.

In Asian countries such, as Malaysia, Indonesia, Thailand and Vietnam the low-voltage switchgear appears a lot in power distribution networks, industrial plants, commercial buildings, photovoltaic systems and infrastructure projects. From my experience engineers have repeatedly confirmed the conclusion about medium- and low-voltage switchgear, over years:

Highly reliable isolation current transformers are essential components for the safe, stable, and compliant operation of switchgear.

I will look at why ICT series isolation current transformers are popular, in the Asian market. I will also show how ICT series isolation current transformers are becoming components, in the switchgear systems. I will examine ICT series isolation transformers from three angles: principles, product characteristics and real application scenarios.

 

1.I want to know what the single phase satuation current transformer

I see that the isolation current transformer (also known as a transformer ICT) sits between the main current transformer (Main CT) and the relay protection, measurement or load. The isolation current transformer core functions include:

• Adjust the secondary current ratio (1A ↔ 5A)
• Correcting current imbalance caused by different CT ratios
• Phase offset caused by transformer wiring method
• Achieve zero-sequence current suppression (Δ connection)
• Reduce the impact of lead load (burden) in long-distance secondary circuits

In switchgear with differential protection, high metering accuracy requirements, or complex system structure, isolation current transformers are almost indispensable components.

2.Core Technical Features of ICT Series Isolation Current Transformers

3.Fully enclosed flame-retardant structure, specially designed for high temperature and high humidity environments.

The ICT series uses a high‑strength resin. The high‑strength flame‑retardant resin provides encapsulation:

• Flame retardant rating: UL-94 V0
• Operating temperature range: -20℃ to +70℃
• Insulation class: Class E (maximum 120°C)

Fully enclosed, self-extinguishing casing; impact-resistant and aging-resistant.

I have found that the measure is very important, in areas that’re hot, humid and have a lot of spray such, as Malaysia and Indonesia. I have found that the measure can lower the chance of insulation aging and creepage caused by the environment.

4.The high electrical isolation keeps switchgears system safe. The high electrical isolation protects switchgears system from any fault.

• Rated operating voltage: 0.72kV
• Power frequency withstand voltage: 4kV / 50Hz / 1min
• Complies with standards: IEC 185, IEC 44-1, BS 3938, DIN 42600

I am wondering, in switchgear the secondary side is often connected to what?

Protection relay

Smart meters

Energy Management System (EMS)

SCADA / IoT acquisition module

I have seen that the isolation current transformers cut off the impact of faults, on secondary equipment. The isolation current transformers protect the equipment. I have seen that the isolation current transformers keep the power distribution systems running stable for a time.

3️⃣ Multiple precision levels to meet both protection and metrology needs

ICT series supports:

• Accuracy class: 0.5 / 1.0
• Rated secondary current: 1A or 5A
• Rated load: 5VA / 7.5VA

The rule applies to both:

Relay protection circuit (differential protection, overcurrent protection)

Metering and monitoring loop (energy consumption analysis, current acquisition)

From my experience in Malaysia industrial parks and commercial building projects use a switch cabinet for protection and, for metering. The isolation current transformer links the switch cabinet to the protection function. Links the switch cabinet, to the metering function.

III. Why do I think the isolation current transformers are essential, for the switchgear, in Southeast Asia?

✔ Reason 1: The main current transformer (CT) does not match the load rating. The load current rating uses 1A/5A interchangeably.

I notice this often in world projects:

Main CT output 1A

The relays need 5 amps. The instruments need 5 amps.

Or the opposite.

The isolation current transformer can easily convert 1A to 5A. Also:

Reduce lead load

I make sure the main CT scanner stays in a load range. I watch the load numbers, for the CT scanner each shift.

Improve the overall measurement and protection accuracy.

Reason 2: The unavoidable phase shift problem in differential protection

In transformer differential protection:

The high-voltage side and low-voltage side wiring methods are different (Y / Δ).

There are differences in the proportion of main CT scans.

ICT series isolation current transformers serve the following purposes:

Correction of phase offset

Balanced current vector

Ensure the accuracy of differential protection operation.

This is particularly crucial in Malaysian power grid and industrial substation projects, and is an “implicit rigid requirement” in many engineering specifications.

Reason 3: Zero‑sequence current suppression makes the system anti‑interference capability better. Zero‑sequence current suppression also helps the system stay stable when noise appears.

Add the delta shaped winding to the isolation CT. Adding the delta shaped winding to the isolation CT allows the following:

Eliminating zero-sequence current

Suppressing malfunctions caused by system imbalance

Improve the stability of relay protection systems

The feature helps manage the load environments of Southeast Asia. The feature works with frequency converters, grid‑connected photovoltaics and many nonlinear loads.

5.Typical Application Scenarios (Malaysia & Southeast Asia)

Medium and low voltage switchgear (LV / MV Switchgear)

Industrial plant power distribution system

Commercial complexes and data centers

Photovoltaic, energy storage, and microgrid systems

Transformer differential protection system

Energy Management and Smart Grid Projects

I see that isolation current transformers are components. I also see that isolation current transformers are components that keep the system reliable and compliant.

6.Conclusion: Why is the ICT series isolation current transformer a worthwhile choice?

In short I see that the ICTseries isolation current transformers have these characteristics:

✅ Mature international standard system

✅ Excellent electrical isolation and safety performance

✅ Structural design adapted to the harsh environment of Southeast Asia

✅ Flexible matching with various switchgear and protection schemes

Because of that more switchgear manufacturers, system integrators and power engineering companies, in Malaysia and across Southeast Asia now choose the solution, for the term.

 

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