Product Overview
The LZZBJ9-35/270 indoor epoxy resin cast current transformer is a fully enclosed pillar-type current transformer designed for 35kV / 36kV / 40.5kV medium-voltage power systems. It is used for current measurement, energy metering and relay protection in AC systems with rated frequency of 50Hz or 60Hz. The product adopts epoxy resin casting insulation, with the winding and magnetic core assembly sealed inside the resin body to provide high dielectric strength, moisture resistance and stable mechanical performance for indoor switchgear applications.
This model should be positioned differently from the previous LZZBJ9-35/250F-L. The LZZBJ9-35/270 is a 270-type large-capacity indoor epoxy CT platform for switchgear feeders requiring higher current ratios, multi-core protection outputs and strong short-circuit withstand capability. The catalogue drawing shows two different primary terminal layouts for I1n: 10-1000A and I1n: 1200-3150A, making it suitable for larger current and wider switchgear layout requirements.
Product Type
| Item | Specification |
|---|---|
| Product name | Indoor Epoxy Resin Cast Current Transformer |
| Model | LZZBJ9-35/270 |
| Installation condition | Indoor |
| Structure | Fully enclosed pillar-type epoxy resin cast structure |
| Structure platform | 270-type large-capacity switchgear CT platform |
| Application | Current measurement, energy metering and relay protection |
| 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 reference range according to catalogue data |
| Typical installation | 35kV indoor switchgear, high-current feeder cabinet and protection metering panel |
Model Explanation
- 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.
- 270: 270-type structural platform for larger switchgear layout and high-current terminal arrangement.
Applications
- 35kV, 36kV and 40.5kV indoor medium-voltage AC systems
- High-current feeder cabinets in air-insulated switchgear
- Incoming and outgoing feeder current measurement
- Energy metering and power quality monitoring panels
- Relay protection for transformers, feeders and bus-section circuits
- Industrial substations, utility substations and distribution rooms
- Projects requiring primary current ratings up to 3150A
- Switchgear applications requiring multi-core metering and protection secondary outputs
Features
- 270-type high-current platform: Designed for larger current ratings and wider switchgear layout requirements than compact 250-type CT bodies.
- Wide current coverage: Catalogue data covers typical primary current ranges from 20A to 3150A.
- 35kV / 40.5kV insulation level: Rated insulation level of 40.5/95/185kV for international 35kV-class indoor systems.
- Fully enclosed epoxy casting: The winding and core are sealed inside the cast resin body for dielectric stability and moisture resistance.
- Large terminal layout: Separate primary terminal drawings are provided for 10-1000A and 1200-3150A current ranges.
- Multi-core configuration: Supports combinations of metering and protection windings, including 0.2S/0.5/5P10/5P20 options.
- High short-circuit withstand: Rated short-time thermal current can reach 100kA and rated dynamic current can reach 250kA in higher current ranges.
- Switchgear integration: Wide base, bottom mounting holes and accessible secondary terminal box support indoor cabinet assembly.
Structure Overview
The LZZBJ9-35/270 adopts a fully enclosed epoxy resin cast body with a ribbed external insulation structure. The upper section provides the primary terminal area, while the lower section integrates the secondary terminal box and mounting base. The product body is designed for 35kV-class indoor switchgear where larger conductor connections, higher primary current and multi-winding secondary circuits are required.
The catalogue dimension drawing shows two primary terminal structures. For I1n: 10-1000A, a smaller terminal pattern is used. For I1n: 1200-3150A, a larger terminal pattern is used to match higher conductor current and connection requirements.
Technical Data
| Parameter | Specification |
|---|---|
| Model | LZZBJ9-35/270 |
| Product type | Indoor epoxy resin cast current transformer |
| 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 reference range |
| Accuracy combinations | 0.2S/0.5/5P10/5P20, 0.2S/0.5/5P15/5P15, 0.2S/0.5/5P20/5P20, 0.2S/0.5/5P30/5P30, 0.2S/0.5/5P40/5P40 |
| Rated output | 30/30/30/30VA, 30/30/40/40VA, 30/30/50/50VA, 30/30/20/20VA, 30/30/15/15VA and project-specific combinations |
| Rated short-time thermal current | 150 x I1n, 200 x I1n, 31.5kA, 45kA, 63kA, 80kA or 100kA according to current range |
| Rated dynamic current | 375 x I1n, 500 x I1n, 80kA, 112.5kA, 160kA, 200kA or 250kA according to current range |
| Ambient temperature | -25°C to +40°C |
| Applicable standards | IEC 61869-1, IEC 61869-2, GB/T 20840.1, GB/T 20840.2; legacy GB20840.1-2010 reference by agreement |
Selection Table
| Rated Primary Current (A) |
Accuracy Class Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current |
Rated Dynamic Current |
|---|---|---|---|---|
| 20-40 | 0.2S / 0.5 / 5P10 / 5P10 0.2S / 0.5 / 5P15 / 5P15 0.2S / 0.5 / 5P20 / 5P20 0.2S / 0.5 / 5P30 / 5P30 0.2S / 0.5 / 5P40 / 5P40 |
30/30/30/30 | 150 x I1n | 375 x I1n |
| 50-100 | 30/30/40/40 | 200 x I1n | 500 x I1n | |
| 150-250 | 30/30/50/50 | 31.5kA | 80kA | |
| 300-400 | 30/30/20/20 | 45kA | 112.5kA | |
| 500-600 | 30/30/15/15 | 63kA | 160kA | |
| 750-800 | 30/30/15/15 | 80kA | 200kA | |
| 1000-3150 | Project-specific output | 100kA | 250kA |
Note: If required parameters exceed the above reference range, they can be confirmed by technical agreement between manufacturer and purchaser.
Operating 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.
- 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.
Installation and Dimensions
The LZZBJ9-35/270 is mounted inside 35kV-class air-insulated switchgear or indoor distribution cabinets. The supplied drawing shows a wide base and large insulation body suitable for high-current feeder applications. Reference dimensions include an overall height of approximately 642mm, a body height reference of approximately 452mm, a base length of approximately 580mm, and a side width of approximately 270mm. Final dimensions must follow the approved project drawing.
| Installation Item | Recommended Check Point |
|---|---|
| Switchgear space | Confirm overall height, base length, side width and terminal access space. |
| Current range layout | Use the correct terminal structure for 10-1000A or 1200-3150A ranges. |
| Primary terminals | Check P1 / P2 direction, conductor connection method and insulation clearance. |
| Secondary terminal area | Reserve wiring, testing and inspection access for secondary circuits. |
| Mounting base | Confirm fixing hole arrangement, base support and grounding position. |
| Electrical clearance | Confirm phase-to-ground and phase-to-phase clearance for 40.5kV equipment class. |
| Drawing confirmation | Use the approved outline drawing and wiring diagram for final production. |
Windings & Terminal Marking
The primary terminals are identified as P1 and P2. Secondary terminals are arranged according to the number of metering and protection windings. Multi-core configurations may include independent metering, monitoring and relay protection outputs.
| Terminal | Function | Application Note |
|---|---|---|
| P1 / P2 | Primary terminals | Used for primary current direction and polarity reference. |
| 1S1 / 1S2 | First secondary winding | Usually assigned to metering or measurement circuit. |
| 2S1 / 2S2 | Second secondary winding | Usually assigned to relay protection circuit. |
| 3S1 / 3S2 | Additional protection winding | Used when multiple protection outputs are required. |
| 4S1 / 4S2 | Additional measurement or protection winding | Used for multi-core configurations according to project requirements. |
| Grounding point | Secondary circuit grounding reference | One point of the secondary circuit should be grounded according to project practice. |
Standards and Compliance
For international product pages, the LZZBJ9-35/270 should be specified according to IEC 61869-1 and IEC 61869-2. GB-based documentation can refer to GB/T 20840.1 and GB/T 20840.2. Legacy catalogue references such as GB20840.1-2010 may be retained for tender compatibility, but modern technical pages should use IEC 61869 and GB/T 20840 series as the preferred standard language.
Selection Guide
- Confirm voltage level: Use this model for 35kV / 36kV / 40.5kV indoor switchgear systems.
- Select current range: Confirm whether the project current is within 10-1000A or 1200-3150A, as terminal structures are different.
- Choose secondary current: Select 5A for conventional meters and relays, or 1A for long secondary wiring and lower burden applications.
- Define accuracy classes: Use 0.2S / 0.2 / 0.5 for metering and 5P10 / 5P20 / 5P30 / 5P40 or 10P protection classes for relay protection.
- Check rated output: Match output combinations such as 30/30/30/30VA, 30/30/40/40VA or 30/30/50/50VA with meter, relay and cable burden.
- Verify short-circuit withstand: Confirm thermal and dynamic withstand values against the system fault level.
- Confirm dimensions: Check overall height, base length, side width and switchgear clearance before final selection.
- Approve drawings: Confirm outline drawing, terminal arrangement and wiring diagram before production.