Product Overview
The LXC-10/155-300-60 and LXC-10/155-300-80 double cable track type zero sequence current transformers are indoor cast-resin current transformers designed for zero sequence current detection, cable earth fault protection, and residual current monitoring. The product uses a runway-shaped long oval window, which is suitable for grouped cable layouts, double-cable arrangements, and cabinet structures where several phase conductors need to pass through one common zero sequence detection window.
This series is especially suitable for indoor switchgear, ring network cabinets, cable outlet compartments, and protection cabinets. Compared with a circular zero sequence CT, the double cable track structure provides a wider horizontal cable passage and supports more practical cable routing in compact cabinets. The transformer can be divided into two halves during installation, placed around the existing cable group, and then clamped and fastened into one complete magnetic circuit.
The LXC-10/155-300 series is supplied in two structural depths: LXC-10/155-300-60 and LXC-10/155-300-80. The 60 mm type is suitable for thinner cabinet space and standard protection outputs, while the 80 mm type provides higher rated output for selected current ratios and is suitable for applications requiring larger secondary burden capacity.
Product Type
| Item | Specification |
|---|---|
| Product name | Double Cable Track Type Zero Sequence Current Transformer |
| Model series | LXC-10/155-300-60, LXC-10/155-300-80 |
| Product structure | Indoor cast-resin split-core runway-type zero sequence current transformer |
| Window structure | Long oval / double cable track window for grouped cable passage |
| Window structure code | 155-300 |
| Body depth options | 60 mm and 80 mm structure variants |
| Rated insulation level | 0.72/3kV |
| Rated frequency | 50Hz / 60Hz |
| Rated secondary current | 5A or 1A |
| Protection class | 10P5 / 10P10 |
| Installation location | Indoor |
| Typical applications | Zero sequence current detection, cable earth fault protection, residual current monitoring, relay protection input |
Product Display
Main Applications
- Indoor cable feeder earth fault protection
- Zero sequence current detection for grouped cable or double-cable layouts
- Residual current monitoring in ring network cabinets and medium-voltage switchgear
- Small-current grounding system alarm and trip circuits
- Cable outlet compartment protection where several conductors must pass through one window
- Relay protection signal acquisition for 5A or 1A input devices
- Retrofit protection projects where the CT must be installed around existing cables
Key Technical Features
- Double cable track window: The long oval opening provides a wider cable passage than a circular zero sequence CT, making it suitable for grouped cable routing and cabinet cable outlet structures.
- Split-core installation: The transformer body can be divided into two halves, installed around existing cables, and then combined and clamped into one complete core.
- Cast-resin insulation: Each half of the magnetic core is cast with resin to provide insulation performance, mechanical protection, and stable indoor service.
- Two structure depths: LXC-10/155-300-60 and LXC-10/155-300-80 provide different installation depth and rated output options.
- Zero sequence current detection: Detects residual current caused by single-phase grounding faults and outputs a secondary signal to the protection relay.
- 5A or 1A secondary output: Suitable for common relay protection devices, monitoring units, and current input modules.
- 10P protection classes: 10P5 and 10P10 options are available according to current ratio, rated output, relay burden, and model selection.
Working Principle
The LXC-10 double cable track type zero sequence current transformer measures the vector sum of all phase currents passing through its long oval window. Under normal operating conditions, the currents of the protected conductors are balanced and the vector sum is approximately zero. When a single-phase ground fault, insulation fault, or leakage current condition occurs, the current balance is broken and zero sequence current is generated. The transformer converts this residual current into a secondary signal for relay protection, alarm, or monitoring.
For correct zero sequence protection, all phase conductors of the protected circuit must pass through the same transformer window in the same direction. The long oval window is useful where multiple cables need to pass through the same CT while maintaining cable spacing, bending radius, and cabinet installation clearance.
Structure Introduction
The transformer is designed as a split-core structure. The magnetic core and winding assembly are divided into two half bodies and cast with resin. During installation, the two halves are opened, placed around the cable group, and then combined into one complete transformer by the clamping and fastening mechanism. This design allows installation without removing or cutting the primary cables, which is highly suitable for retrofit cabinet projects and cable outlet protection systems.
| Structure Item | Description |
|---|---|
| Core structure | Split-core design divided into two cast-resin halves |
| Window shape | Long oval / runway / double cable track type |
| Installation method | Open the two halves, place around the cable group, close and clamp the transformer body |
| Primary conductor | Protected three-phase cable group passing through the window |
| Secondary terminal | OS1 / OS2 or S1 / S2 according to terminal marking |
| Typical benefit | Convenient installation around existing cables without disconnecting the primary circuit |
Model Designation
The model code can be interpreted as follows:
| Code | Meaning |
|---|---|
| L | Current transformer |
| X | Zero sequence current transformer type |
| C | Cast-resin / structure series code |
| 10 | Product design series code |
| 155-300 | Runway-type window structure size code |
| 60 / 80 | Body depth / structure thickness code |
Technical Data
| Item | Specification |
|---|---|
| Model | LXC-10/155-300-60, LXC-10/155-300-80 |
| Product type | Indoor double cable track type zero sequence current transformer |
| Rated insulation level | 0.72/3kV |
| Rated frequency | 50Hz / 60Hz |
| Rated secondary current | 5A or 1A |
| Protection class | 10P5 / 10P10 |
| Ambient temperature | -25°C to +40°C |
| Insulation structure | Indoor cast-resin insulation |
| Applicable standards | GB 20840.1-2010, GB 20840.2-2014; customer-specific requirements can be confirmed by agreement |
Rated Current Ratio and Output Reference
| Model | Rated
Current Ratio |
Rated
Secondary Current |
Rated Output
or 10P5 (VA) |
Rated Output for
10P10 (VA) |
|---|---|---|---|---|
| LXC-10/155-300-60 | 50/5 | 5A | 1.5 | 0.5 |
| 75/5 | 5A | 2.5 | 0.5 | |
| 100/5 | 5A | 2.5 | 1 | |
| 150/5 | 5A | 3.75 | 1.5 | |
| 200/5 | 5A | 5 | 1.5 | |
| 300–400/5 | 5A | 7.5 | 2.5 | |
| 50/1 | 1A | 1.5 | 0.5 | |
| 75/1 | 1A | 2.5 | 1 | |
| 100/1 | 1A | 3.75 | 1.5 | |
| 150/1 | 1A | 5 | 2.5 | |
| LXC-10/155-300-80 | 20/5 | 5A | 0.5 | – |
| 50/5 | 5A | 2.5 | 1 | |
| 75/5 | 5A | 2.5 | 1.5 | |
| 100/5 | 5A | 3.75 | 1.5 | |
| 150/5 | 5A | 7.5 | 2.5 | |
| 200/5 | 5A | 10 | 3.75 | |
| 300–400/5 | 5A | 15 | 5 | |
| 20/1 | 1A | 1 | 0.5 | |
| 50/1 | 1A | 2.5 | 1 | |
| 75/1 | 1A | 3.75 | 1.5 | |
| 100/1 | 1A | 5 | 2.5 | |
| 150/1 | 1A | 7.5 | 3.75 |
Note: If required parameters exceed the listed catalogue range, current ratio, protection class and rated output can be confirmed through technical agreement.
Service Conditions
- Installation location: indoor
- Rated insulation level: 0.72/3kV
- Rated frequency: 50Hz / 60Hz
- Ambient temperature: -25°C to +40°C
- The installation environment should be free from severe vibration, corrosive gas, conductive dust, explosive medium, heavy moisture and serious pollution.
- All phase conductors of the protected circuit should pass through the same transformer window in the same direction.
- The cable group should pass through the long oval window without mechanical stress on the transformer body.
- The split-core joint surface should be clean, aligned and clamped firmly after installation.
- For special cable arrangement, relay model, wiring distance, burden or protection setting requirements, technical confirmation is recommended before ordering.
Standards and Compliance
The LXC-10 runway-type zero sequence current transformer series is designed according to GB 20840.1-2010 and GB 20840.2-2014, and can be supplied according to customer-specific project requirements. Final current ratio, protection class, rated output, routine test items, nameplate data and wiring requirements should be confirmed in the technical agreement.
Installation and Dimensions
Overall Dimensions Reference
| Model | Outer
Length |
Inner
Length Reference |
Window
Height Reference |
Overall
Height |
Mounting
Length |
Body Depth
Reference |
|---|---|---|---|---|---|---|
| LXC-10/155-300-60 | 300 | 252 | 100 | 155 | 280 | 80±2 mm side reference / 60 mm structure code |
| LXC-10/155-300-80 | 300 | 252 | 100 | 155 | 280 | 100±2 mm side reference / 80 mm structure code |
Unit: mm. Final dimensions, mounting holes, terminal position and installation clearance are subject to the approved outline drawing.
The LXC-10/155-300-60 and LXC-10/155-300-80 models are installed around the protected cable group or conductor group. The runway-type opening allows multiple conductors to pass through the same transformer window. Secondary terminals should be wired according to the protection relay diagram. The transformer should be fixed on the cabinet base or mounting bracket to avoid movement during operation.
Installation Procedure
- Confirm conductor arrangement: Check that the full protected cable group can pass through the runway-type window with enough clearance.
- Open the transformer body: Separate the two cast-resin halves carefully according to the mechanical structure.
- Place around the cable group: Position all protected phase conductors inside the same window and keep the direction consistent.
- Close and clamp the body: Align the two halves, close the magnetic circuit and tighten the clamping structure evenly.
- Fix the mounting base: Secure the transformer on the cabinet frame or base plate according to the drawing.
- Connect secondary terminals: Connect OS1 and OS2, or S1 and S2 where marked, to the relay protection input.
- Commission the circuit: Check polarity, relay setting, secondary continuity and mechanical fastening before energizing.
Wiring Reference
| Terminal | Function | Wiring Note |
|---|---|---|
| OS1 / S1 | Secondary output terminal | Connect to relay or monitoring input according to polarity requirement |
| OS2 / S2 | Secondary output terminal | Connect to relay or monitoring return terminal |
| A / B / C conductors | Primary cable group | All protected phase conductors should pass through the same window |
Connection and Wiring Notes
- All phase conductors of the protected circuit should pass through the same runway-type window in the same direction.
- Do not pass only one phase conductor through the window when the transformer is used for zero sequence protection.
- Connect secondary terminals OS1 and OS2, or S1 and S2 where marked, according to the relay wiring diagram.
- Check secondary wiring continuity, terminal tightening and relay setting before energizing.
- The secondary circuit of a current transformer must not be open-circuited when the primary circuit is energized.
- Secondary grounding and terminal protection should comply with project specifications and local electrical regulations.
Installation and Safety Notes
- Confirm the model, window size, body depth, current ratio, secondary current, protection class and rated output before installation.
- Select LXC-10/155-300-60 where a thinner structure is required.
- Select LXC-10/155-300-80 where higher rated output or deeper body structure is required.
- Check that the cable group can pass through the runway-type window with sufficient clearance and bending radius.
- Keep the split-core joint surface clean and avoid dust, metal chips or mechanical damage.
- Do not operate the transformer if the two halves are not fully clamped or aligned.
- Installation, testing and maintenance should be performed by qualified electrical personnel.
Ordering Information
Please provide the following information when ordering or requesting a quotation:
- Product model: LXC-10/155-300-60 or LXC-10/155-300-80
- Rated current ratio, such as 100/5, 200/5, 300/5, 400/5, 50/1 or 100/1
- Rated secondary current: 5A or 1A
- Required protection class: 10P5 or 10P10
- Rated output / burden in VA
- Cable group arrangement and maximum outside dimension
- Relay model, protection scheme and grounding fault detection requirement
- Installation environment, cabinet layout, quantity, drawings, labels, certificates and packaging requirements
Selection Guidelines
- Confirm cable arrangement: Select the runway-type LXC-10 series when multiple cables or a wide cable group must pass through the same zero sequence CT.
- Confirm structure depth: Choose LXC-10/155-300-60 for thinner installation space or LXC-10/155-300-80 for higher output capability.
- Confirm current ratio: Select the current ratio according to relay input and protection setting requirements.
- Select secondary current: Choose 5A or 1A according to the connected relay or monitoring device.
- Choose protection class: Select 10P5 or 10P10 according to protection circuit requirements.
- Check rated burden: Ensure the relay input, secondary wiring and terminal burden do not exceed the rated output.
- Confirm installation space: Check body depth, mounting position and cable bending space before ordering.