Overview

The LJK-φ100~φ240 Indoor High-Precision Zero Sequence Current Transformer is engineered for exceptional reliability and long-term durability, making it a superior solution for advanced power systems. Constructed with a robust ABS engineering plastic housing and a fully resin-cast sealed structure, this transformer ensures enhanced insulation, corrosion resistance, and consistent performance even under demanding conditions. The use of advanced cooling and anti-rust technologies guarantees stability and efficiency throughout extended operational periods.

LJK indoor Zero current transformer is Designed with high sensitivity and outstanding linearity, LJK-φ100 Indoor Cast-Resin Zero Sequence Current  transformer offers dependable performance across a wide range of applications. It is compatible with both traditional electromagnetic relay protection systems and modern microcomputer-based protection devices, delivering seamless integration into diverse setups. Easy to install and maintain, this transformer stands out as a versatile and reliable choice for zero-sequence current measurement and fault detection. Its innovative design and compliance with modern electrical and safety standards make it an essential component for ensuring the efficiency and security of today’s electrical systems.

Type Designation of LJK Current Transformer

The type designation for the LJK-Φ80~240 Current Transformer is as follows:

• L: Current Transformer
• J: Earthing Protection
• K: Split-core Type
• Φ110~240: Nominal Inner Diameter

Operating Conditions

1. Ambient Temperature: -25°C to +40°C.
2. Altitude: Below 2000 meters (for high-altitude applications, please specify when placing an order).
3. Relative Humidity: ≤95%.
4. Environmental Conditions: The surrounding medium must be free of conductive dust, metallic particles, corrosive gases, or mold that could damage insulation.

Technical Data of  LJK

1. Voltage Range: 0.4kV to 66kV
2. Grid Frequency: 0 to 500Hz (supports 3rd harmonic at 150Hz and 5th harmonic at 250Hz)
3. Terminal Identification: Primary conductor passes through the “L1” side on the front of the transformer, and the secondary is labeled as “K1”.
4. Product Specifications: Refer to the diagrams and tables for model details, technical data, and dimensions.

Outline and Installation Dimensions

Dimensions Table of High-Precision Zero Sequence Current Transformer

Model	A	B	C	E	F	a	b	D (φ)	d (φ)
LJK-100	214	190	141	50	188	152	184	102	9
LJK-120	232	208	160	50	206	170	202	120	9
LJK-140	275	255	178	71	245	200	255	145	9
LJK-160	293	267	195	71	262	220	271	165	9
LJK-180	317	290	255	71	302	260	297	187	9
LJK-200	370	348	285	85	330	310	340	206	9
LJK-240	410	383	315	79	383	336	390	246	10.5

Note: For special installation requirements, customized dimensions, or detailed guidance, please refer to the product technical drawings or contact our technical team for tailored assistance.

Installation Instructions

1. For integrated transformers, installation must be completed before laying the cables. Ensure the transformer is positioned correctly before threading the cables through it.
2. Open-type transformers can be installed at any time. Follow the steps below for proper installation:
   • Remove the connecting plate labeled “K1” and “K2.”
   • Loosen the screws on the top of the transformer to separate it into two parts.
3.  Place the transformer around the cable, clean the two contact surfaces thoroughly, and apply a thin layer of anti-rust oil. Align the two parts of the transformer carefully and fasten the screws tightly to avoid performance issues.
4. Secure the connecting plate back to “K1” and “K2.”
5. Ensure the top and bottom parts of the open-type transformer remain paired and are not swapped with other transformer components.

Ordering Information

To ensure accurate processing and delivery of your order, please specify the following details:

1. Voltage Level: Indicate the required voltage range (e.g., 0.4kV–66kV).
2. Current Ratio: Provide the required primary-to-secondary current ratio.
3. Accuracy Class and Load: Include the desired accuracy level and rated secondary load.
4. Insulation Level: Mention the insulation specifications based on your application.
5. Use Environment: Describe the operating conditions, such as temperature, humidity, and installation location.
6. Special Requirements: For custom configurations, special dimensions high-precision CT, or non-standard specifications, please contact our technical team to discuss your specific needs.

FAQs of LJK High-Precision Zero Sequence Current Transformer

1. What is the primary application of the LJK-φ100~φ240 transformer?
   It is designed for accurate zero-sequence current measurement, fault detection, and relay protection in advanced indoor power systems.
2. Can this transformer be used in high-altitude installations?
   Yes, it can be used up to 2000 meters. For higher altitudes, specific adjustments must be requested during the ordering process.
3. How does the transformer handle humid environments?
   The transformer features a fully resin-cast sealed structure and advanced anti-rust technologies, ensuring reliable performance in environments with humidity levels up to 95%.
4. Is the transformer compatible with modern protection systems?
   Yes, it is compatible with both traditional electromagnetic relay protection systems and modern microcomputer-based protection devices.
5. Can the transformer be customized for specific requirements?
   Yes, customization is available for voltage levels, current ratios, accuracy classes, and dimensions. Contact the technical team for tailored solutions.

• Working Principle of Zero-Sequence Current Transformers
• Causes, and Solutions for Abnormal Heating in 10KV Current Transformers
• Analysis of the Impact of Incorrect CT S1 and S2 Connections and Reversed Input Lines
• Causes of 35KV Current Transformer Damage
• Common Fault Handling for Current and Voltage Transformers
• Number of Permissible Grounding Points in the Secondary Circuit of Voltage Transformers