Overview
The LZZBJ9-35/250F-L is a pillar-type epoxy resin cast current transformer designed for indoor use in 35kV, 36kV, and 40.5kV medium-voltage AC power systems. It features a fully enclosed cast-resin insulation structure, providing high dielectric strength and long-term operational stability under standard 50Hz or 60Hz frequencies.
This heavy-duty CT supports primary currents from 15A to 2500A and offers combined metering (e.g., 0.2S, 0.5) and protection (e.g., 5P15 to 5P40) windings. It is suitable for air-insulated switchgear, indoor distribution cabinets, and metering panels where reliable current transformation, high thermal withstand capability, and stable performance are required.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 35kV / 36kV / 40.5kV |
| Rated insulation level | 40.5/95/185kV |
| Rated frequency | 50Hz or 60Hz |
| Rated secondary current | 5A or 1A |
| Primary current range | 15A – 2500A |
| Metering accuracy classes | 0.2S, 0.5 |
| Protection accuracy classes | 5P15, 5P20, 5P30, 5P40 |
| Thermal short-time current | Up to 100kA (1s) |
| Dynamic withstand current | Up to 250kA peak |
| Installation environment | Indoor |
| Insulation material | Epoxy resin cast |
| Structure type | Pillar-type, support-mounted |
Model Designation
- L: Current transformer.
- Z: Pillar-type / support-type structure.
- Z: Epoxy resin casting insulation.
- B: Current transformer series with measurement and protection winding options.
- J: Reinforced / protection-capable design reference.
- 9: Design sequence / product platform code.
- 35: 35kV-class product, suitable for 35kV, 36kV and 40.5kV systems.
- 250F: 250mm-class cast-resin body platform with a large-current structural layout.
Construction
The LZZBJ9-35/250F-L features a fully enclosed pillar-type construction with an epoxy resin cast insulation body that encapsulates the magnetic core and windings. This sealed design enhances dielectric stability and protects against environmental contamination in indoor switchgear environments. The upper portion of the housing is wide and ribbed to extend the creepage distance, ensuring reliable performance at 35kV-class voltages.
Mechanical support is provided by a robust metal base, enabling secure mounting within air-insulated switchgear or distribution panels. The primary terminal configuration varies based on the rated primary current: one layout is used for 15A to 1250A, while a larger, reinforced terminal structure is employed for currents above 1250A up to 2500A. Secondary terminals are accessible for wiring, testing, and inspection, supporting flexible output configurations such as 30/60/60VA or 30/25/25VA depending on application requirements.
Technical Parameters
Service Conditions
- Installation: Indoor installation for 35kV / 36kV / 40.5kV switchgear and distribution systems.
- Rated frequency: 50Hz or 60Hz.
- Ambient temperature: -25°C to +40°C.
- Site condition: No severe vibration, shock or mechanical impact at the installation site.
- Humidity: Indoor service without severe condensation; special requirements should be confirmed by project agreement.
Technical Parameters
The LZZBJ9-35/250F-L is an indoor pillar-type epoxy resin cast current transformer designed for 35kV / 36kV / 40.5kV systems, with a rated insulation level of 40.5/95/185kV. It operates within an ambient temperature range of -25°C to +40°C, complies with IEC 61869-1/-2 and GB/T 20840.1/.2 standards, and supports primary currents from 15A to 2500A.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 15~40 | 0.2S/5P15(10P15)/5P15(10P15) 0.2S/5P20(10P20)/5P20(10P20) 0.2S/5P30(10P30)/5P30(10P30) 0.2S/5P40(10P40)/5P40(10P40) 0.5/5P15(10P15)/5P15(10P15) 0.5/5P20(10P20)/5P20(10P20) 0.5/5P30(10P30)/5P30(10P30) 0.5/5P40(10P40)/5P40(10P40) |
30/60/60 30/40/40 30/25/25 30/15/15 30/60/60 30/40/40 30/25/25 30/15/15 |
150*I1n(A) | 375*I1n(A) |
| 50~100 | 200*I1n(A) | 500*I1n(A) | ||
| 150~250 | 31.5 | 100 | ||
| 300~400 | 45 | 112.5 | ||
| 500~600 | 63 | 160 | ||
| 750~800 | 80 | 200 | ||
| 1000~2500 | 100 | 250 |
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 15~40 | 0.2S/0.5/5P10(10P10)/5P10(10P10) 0.2S/0.5/5P15(10P15)/5P15(10P15) 0.2S/0.5/5P20(10P20)/5P20(10P20) 0.2S/0.5/5P30(10P30)/5P30(10P30) 0.2S/0.5/5P40(10P40)/5P40(10P40) |
30/30/80/80 30/30/50/50 30/30/40/40 30/30/20/20 30/30/10/10 |
150*I1n(A) | 375*I1n(A) |
| 50~100 | 200*I1n(A) | 500*I1n(A) | ||
| 150~250 | 31.5 | 100 | ||
| 300~400 | 45 | 112.5 | ||
| 500~600 | 63 | 160 | ||
| 750~800 | 80 | 200 | ||
| 1000~2500 | 100 | 250 |
Installation & Wiring
Installation Diagram
The LZZBJ9-35/250F-L pillar-type cast-resin current transformer is designed for installation within 35kV-class air-insulated switchgear or indoor distribution cabinets. It is secured via a mounting base with predefined fixing holes, and requires adequate clearance around primary and secondary terminals for safe connection, maintenance, and inspection.
Selection & FAQs
Selection Guide
- Choose three or four cores before selecting VA. Standard 250F-L schemes use one measuring and two protection cores; alternative schemes add a second class 0.5 measuring core.
- Select the 15A–2500A ratio and terminal structure. Versions above 1250A use a larger reinforced primary interface; verify busbar, temperature rise and cabinet clearance.
- Match ALF and burden per protection core. Available 5P classes extend from ALF 10 to 40, with output varying significantly by current group and core arrangement.
- Do not infer the meaning of the L suffix. The page does not define it reliably; confirm the exact 250F-L mechanical outline, mounting base and terminal box against other 250mm variants.
- Complete fault and insulation coordination. Verify 1-second thermal and peak current, partial discharge, creepage, altitude, core terminals, 1A or 5A secondary and IEC 61869 documentation.
Frequently Asked Questions
Q1: Can this 40.5kV current transformer be installed outdoors?
No, it is strictly designed for indoor switchgear installation. It requires an environment free from severe condensation and mechanical shock. Outdoor versions are subject to confirmation.
Q2: Which accuracy class is best for protective relaying?
Select 5P or 10P classes for protection circuits. These ensure accurate transformation during fault conditions up to 15 or 20 times rated current. Factory settings apply.
Q3: What is the rated short-time thermal current capacity?
Ratings scale with primary current selection. Thermal and dynamic limits reach maximum kA/1s values detailed in the technical table. Confirm exact short-circuit ratings for your specific application.
Q4: Are these current transformers compliant with international standards?
Yes, they fully comply with IEC 61869-1/-2 and GB/T 20840.1/.2 standards. Type test reports and compliance certificates are provided upon request.
Q5: Do you offer customized primary current ratios?
Yes, primary currents from 15A to 2500A are supported. Custom ratios and accuracy combinations are available. Contact our sales team with your exact ratio requirements.
Q6: Where is this pillar-type current transformer typically applied?
This transformer is applied in 35kV to 40.5kV indoor distribution systems. The epoxy resin cast design ensures high insulation levels of 40.5/95/185kV. Request datasheets for specific switchgear integration.
Q7: Does this 35kV transformer support 60Hz power systems?
Yes, it operates reliably at both 50Hz and 60Hz rated frequencies. Specify your grid frequency during ordering to ensure correct factory calibration.