Part 1: Industry Pain Points

In recent years, the Thai government has continuously promoted the development of rooftop photovoltaic (PV) systems for industrial and commercial use, leading to rapid growth in PV projects in factories, commercial buildings, and industrial parks. In PV systems, the current transformer (CT), although a small component, directly affects the accuracy of current acquisition, the effectiveness of reverse current control, the reliability of energy management data, and the stability of system operation. Choosing the right CT is crucial in PV projects.

Common CT selection problems:

1. Mismatched CT specifications (e.g., mistakenly selecting 100A/5A instead of 100A/50mA), resulting in abnormal data and reverse current control failure.

2. Different projects require different outputs: 5A/1A is suitable for traditional meters; 50mA and 100mA are suitable for hybrid inverters, reverse current monitoring, and specific inverter monitoring.

Part 2: Low-Voltage CT Basics

Low-voltage CTs can be divided into three types: 5A/1A output CTs, mA output CTs, and open-type CTs.

1. 5A/1A output CT: Suitable for industrial and commercial PV, EMS, and electricity meters.

2. mA Output CT: Suitable for hybrid inverters, reverse current monitoring, and power generation monitoring. Common outputs are 350A/50mA, 100A/50mA, 100A/100mA, and 120A/40mA.

3. Open-Type CT: No wiring disconnection or power outage required, making it particularly suitable for retrofitting existing photovoltaic systems. The AKH-0.66/K series can be installed without removing the primary busbar, reducing downtime and labor costs.

Part 3: ACREL Product Solutions

The AKH-0.66/K-Φ series supports low current outputs of 20mA, 40mA, 50mA, and 100mA, suitable for compact monitoring systems and reverse current monitoring of some branded inverters. A photovoltaic EPC project in Thailand purchased over 2300 AKH-0.66/K-Φ series current transformers for its photovoltaic project.

https://www.acrel.co.th/shop/akh-066-k-24-series-split-core-current-transformer

(Click picture for details)

The AKH-0.66/K series is suitable for AC combiner cabinets, grid-connected cabinets, low-voltage distribution cabinets, EMS, and energy monitoring systems, supporting various opening sizes and current ratios.

https://www.acrel.co.th/shop/akh-066k-square-split-core-current-transformer

(Click picture for details)

Part 4: Typical Applications

① Photovoltaic Zero Export System: PV → Inverter → CT → Meter.

② Existing Photovoltaic Power Station Retrofit: Adds power monitoring, energy management, and zero export prevention without power outages.

③ Industrial and Commercial Energy Monitoring: Load analysis, energy consumption statistics, and demand monitoring for factories, warehouses, and commercial buildings.

Part 5: CT Selection Guide
Steps:

① Confirm primary current;

② Confirm output signal (5A/1A/50mA/100mA/other);

③ Confirm installation object (cable/busbar);

④ Confirm accuracy class.

Part 6: Why Choose ACREL

• Wide current coverage

• Supports 5A, 1A, and various mA outputs

• Open-type design suitable for retrofit projects

• Suitable for photovoltaic, backflow prevention, and power generation monitoring

• Can be integrated with meters and energy management system