Overview
The LZZBJ9-35/270 is an indoor epoxy resin cast current transformer designed for 35kV, 36kV, and 40.5kV medium-voltage AC systems operating at 50Hz or 60Hz. It features a fully enclosed pillar-type structure with windings and magnetic core sealed within a cast-resin body, ensuring high dielectric strength, moisture resistance, and mechanical stability for indoor switchgear environments.
This transformer supports current measurement, energy metering, and relay protection functions with typical accuracy classes including 0.2S, 0.5, 5P10, and 5P20. It is suitable for use in industrial and utility substations, high-current feeder cabinets, and protection panels where primary currents range from 20A to 3150A and robust short-circuit withstand capability is 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 | 20A to 3150A |
| Short-time thermal current | Up to 100kA |
| Dynamic current withstand | Up to 250kA |
| Accuracy classes | 0.2S, 0.5, 5P10, 5P20 |
| Installation condition | Indoor |
| Insulation material | Epoxy resin cast |
| Structure type | Fully enclosed pillar-type |
| Application | Measurement, metering, protection |
Construction
The LZZBJ9-35/270 features a fully enclosed epoxy resin cast body with a ribbed external insulation surface. The internal magnetic core and windings are completely encapsulated within the cast-resin matrix, providing excellent dielectric performance, moisture resistance, and long-term operational stability. The upper portion of the unit houses the primary terminals, while the lower section integrates a secondary terminal box and mounting base. Two distinct primary terminal configurations are provided: one for I1n ratings from 10A to 1000A and another for higher ratings from 1200A to 3150A, accommodating larger conductor connections and enhanced current-carrying requirements in 35kV-class indoor switchgear assemblies.
Technical Parameters
Service Conditions
- Ambient temperature: -25°C to +40°C
- Installation: Indoor installation for 35kV / 36kV / 40.5kV switchgear and distribution systems.
- Site condition: No severe vibration, shock or mechanical impact at the installation site.
- Air quality: Ambient air should not be seriously polluted by dust, smoke, corrosive gases, vapours or salt.
- Humidity: Indoor service without severe condensation; special requirements should be confirmed by project agreement.
- Maintenance: Keep the epoxy resin surface clean and dry to maintain insulation performance.
- Installation check: Confirm the correct terminal layout according to the selected primary current range.
Technical Parameters
The LZZBJ9-35/270 is an indoor epoxy resin cast current transformer designed for 35kV / 36kV / 40.5kV systems, featuring a rated insulation level of 40.5/95/185kV and operating within an ambient temperature range of -25°C to +40°C. It complies with IEC 61869-1, IEC 61869-2, GB/T 20840.1, and GB/T 20840.2 standards, supporting a primary current range from 20A to 3150A.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 20~40 | 0.2S/0.5/5P110(10P10)/5P15(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) |
30/30/30/30 30/30/40/40 30/30/50/50 |
150*I1n(A) | 375*I1n(A) |
| 50~100 | 200*I1n(A) | 500*I1n(A) | ||
| 150~250 | 31.5 | 80 | ||
| 300~400 | 45 | 112.5 | ||
| 500~600 | 63 | 160 | ||
| 750~800 | 80 | 200 | ||
| 1000~3150 | 100 | 250 |
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 20~40 | 0.2S/0.5/5P110(10P10)/5P10(10P10)/5P10(10P10) 0.2S/0.5/5P15(10P15)/5P15(10P15)/5P15(10P15) 0.2S/0.5/5P20(10P20)/5P20(10P20)/5P20(10P20) 0.2S/0.5/5P30(10P30)/5P30(10P30)/5P30(10P30) 0.2S/0.5/5P40(10P40)/5P40(10P40)/5P10(10P40) |
30/30/50/50/50 30/30/40/40/40 30/30/20/20/20 20/20/15/15/15 |
150*I1n(A) | 375*I1n(A) |
| 50~100 | 200*I1n(A) | 500*I1n(A) | ||
| 150~250 | 31.5 | 80 | ||
| 300~400 | 45 | 112.5 | ||
| 500~600 | 63 | 160 | ||
| 750~800 | 80 | 200 | ||
| 1000~3150 | 100 | 250 |
Installation & Wiring
Installation Diagram
The LZZBJ9-35/270 is designed for installation within 35kV-class air-insulated switchgear or indoor distribution cabinets. It features a wide mounting base and large cast-resin insulation body to accommodate high-current feeder applications. Installation must ensure proper alignment with primary conductors, adequate electrical clearances, and accessibility for secondary wiring and maintenance.
Selection & FAQs
Selection Guide
- Select the 270 platform from cabinet width and burden needs. It provides a four-core structure with lower standard protection VA than the 300F platform; confirm body, base and terminal geometry.
- Choose the 20A–3150A primary ratio. Match load and 1A or 5A secondary, noting the reinforced terminal arrangement required from approximately 1200A upward.
- Specify all four cores in order. The detailed table uses 0.2S/0.5 plus two 5P cores; state each protection ALF and VA rather than relying on the family code.
- Confirm any mixed-protection combination. A summary line suggests 5P10/5P20, while the detailed rows primarily show two identical ALFs; require a signed winding schedule for mixed classes.
- Verify high-current and installation data. For 1000A–3150A, obtain project-specific outputs, terminal temperature rise, 100kA/1s and 250kA peak confirmation, clearances, partial discharge and mounting forces.
Frequently Asked Questions
Q1: Can this 35kV current transformer be used on 40.5kV systems?
Yes, it is designed for 35kV, 36kV, and 40.5kV indoor distribution systems. The rated insulation level is 40.5/95/185kV. Confirm your specific system voltage during ordering.
Q2: What are the ambient temperature limits for indoor installation?
The operating ambient temperature range is -25°C to +40°C. Ensure the installation site has no severe condensation or corrosive gases. Contact us for special environmental requirements.
Q3: Which international standards does this epoxy resin CT comply with?
It fully complies with IEC 61869-1, IEC 61869-2, GB/T 20840.1, and GB/T 20840.2 standards. This ensures reliable performance for 20A to 3150A primary current ranges.
Q4: What factory tests are performed before shipment?
Routine tests are performed according to IEC and GB standards. Details regarding specific special tests or third-party certifications are subject to confirmation. Please contact us for details.
Q5: How do I select the correct primary current rating?
The primary current range is customizable from 20A to 3150A. You must confirm the correct terminal layout according to your selected current range. Contact sales for custom ratio options.
Q6: Where is the LZZBJ9-35/270 current transformer typically applied?
It is applied in 35kV to 40.5kV indoor switchgear and power distribution systems. The epoxy resin cast design ensures high insulation performance. Verify mechanical clearances with your switchgear manufacturer.
Q7: How should the epoxy resin surface be maintained after installation?
Keep the epoxy resin surface clean and dry to maintain optimal insulation performance. Ensure the installation site is free from severe vibration or mechanical impact.