Product Overview
The LZZBJ9-35G/220 indoor epoxy resin cast current transformer is a compact 35kV-class 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 indoor AC systems with rated frequency of 50Hz or 60Hz. The product adopts epoxy resin casting insulation, with the core and secondary winding system sealed inside the resin body to provide stable dielectric performance, moisture resistance and reliable mechanical strength for indoor switchgear applications.
This model should be positioned differently from the previous LZZBJ9-36 / LZZBJ9-35/300F and LZZBJ9-35/270 platforms. The LZZBJ9-35G/220 is a compact 220mm-width indoor epoxy CT platform, mainly suitable for switchgear feeders with medium current ratings, limited installation width and standard metering/protection combinations. The catalogue drawing shows a 220mm side-width body, compact base, and two wiring/terminal layouts for I1n: 5-600A, including series and parallel ratio connection examples such as 100/5A and 200/5A. This makes the model suitable for projects requiring a compact 35kV CT with flexible ratio configuration rather than a large 3150A feeder platform.
Product Type
| Item | Specification |
|---|---|
| Product name | Indoor Epoxy Resin Cast Current Transformer |
| Model | LZZBJ9-35G/220 |
| Installation condition | Indoor |
| Structure | Fully enclosed pillar-type epoxy resin cast structure |
| Structure platform | 220mm compact 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 |
| Reference primary current range | 50A to 1000A according to catalogue table; dimensional drawing shows 5A to 600A terminal layout reference |
| Typical installation | 35kV indoor switchgear, compact feeder cabinet, metering cabinet and relay protection 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.
- 35G: 35kV-class compact design version, suitable for 35kV / 36kV / 40.5kV indoor systems.
- 220: 220mm-class compact body width / structural platform.
Applications
- 35kV, 36kV and 40.5kV indoor medium-voltage AC systems
- Compact air-insulated switchgear and indoor distribution cabinets
- Feeder current measurement and energy metering circuits
- Relay protection for transformer feeders, outgoing feeders and bus-section circuits
- Medium-current switchgear panels where a compact 220mm-width CT body is preferred
- Projects requiring combined metering and protection output from one CT
- Applications requiring ratio configuration through series/parallel primary connection design
- Indoor substations, industrial power rooms and utility distribution systems
Features
- Compact 220mm platform: Designed for switchgear layouts where space is limited but 40.5kV insulation coordination is still required.
- 35kV / 36kV international voltage positioning: Suitable for international 36kV equipment documentation with rated insulation level 40.5/95/185kV.
- Fully enclosed epoxy resin casting: The active parts are sealed inside the resin body to improve dielectric stability and moisture resistance.
- Metering and protection in one unit: Accuracy combinations support measurement and relay protection functions in the same CT platform.
- Flexible output selection: Rated outputs such as 20VA, 30VA and 30-50VA are available depending on accuracy class and winding configuration.
- Series / parallel ratio connection reference: The drawing includes ratio connection examples such as 100/5A and 200/5A for project-specific wiring design.
- Moderate short-circuit withstand: Rated dynamic current values up to 100kA are shown in the catalogue table for the higher current ranges.
- Accessible secondary terminal area: The lower terminal section supports wiring, testing and inspection inside the cabinet.
Structure Overview
The LZZBJ9-35G/220 adopts a compact fully enclosed epoxy resin cast structure. The upper terminal area provides the primary connection interface, while the lower section includes the secondary terminal block and mounting base. The 220mm side-width structure is suitable for cabinets where larger 270mm or 300F-class current transformers may be unnecessary or difficult to fit.
The supplied dimension drawing shows two connection arrangements for I1n: 5-600A. One layout is a standard terminal arrangement, and the other includes series and parallel connection examples for ratio configuration. This gives the model a more flexible positioning for medium-current switchgear projects where the same physical platform may support different primary current configurations.
Operating Principle
The current transformer converts the primary current in a 35kV / 36kV / 40.5kV circuit into a standardized secondary current, normally 5A or 1A. The secondary output is connected to energy meters, ammeters, protection relays or power monitoring devices. This enables safe measurement and protection control while keeping the secondary circuit isolated from the high-voltage primary system.
For metering windings, the CT must maintain the required ratio accuracy and phase displacement under the specified burden. For protection windings, the CT must provide dependable secondary output under fault-current conditions. Current ratio, accuracy class, rated output, short-time thermal current and dynamic current should therefore be selected according to cabinet design, meter/relay burden and the short-circuit level of the power system.
Technical Data
| Parameter | Specification |
|---|---|
| Model | LZZBJ9-35G/220 |
| 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 |
| Reference primary current range | 50A to 1000A according to catalogue table; 5A to 600A terminal layout reference shown in drawing |
| Accuracy classes | 0.2S, 0.5, 10P10, 10P15, 10P20 and related combinations |
| Rated output | 20VA, 30VA, 30-50VA and project-specific combinations according to accuracy class |
| Rated short-time thermal current | 8.2kA to 40kA reference range according to catalogue table |
| Rated dynamic current | 20kA to 100kA reference range according to catalogue table |
| Ambient temperature | -5°C to +40°C |
| Applicable standards | IEC 61869-1, IEC 61869-2, GB/T 20840.1, GB/T 20840.2; legacy GB20840.2-2014 reference by agreement |
Selection Table
| Rated Primary Current (A) |
Accuracy Class Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current |
Rated Dynamic Current |
|---|---|---|---|---|
| 50 | 0.2S / 0.5 0.2S / 10P10 0.5 / 10P10 0.2S / 10P15 0.5 / 10P15 0.2S / 10P20 0.5 / 10P20 |
20 30 30-50 |
8.2kA | 20kA |
| 75 | 12kA | 30kA | ||
| 100 | 16kA | 40kA | ||
| 150 | 20kA | 50kA | ||
| 200 | 20kA | 50kA | ||
| 300 | 20kA | 50kA | ||
| 400 | ||||
| 500 | ||||
| 600 / 750 / 800 | 31.5kA | 80kA | ||
| 1000 | 40kA | 100kA |
Note: Rated output and relative accuracy class may only use one selected combination. 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: -5°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 terminal layout, series/parallel wiring and ratio marking before energizing.
Installation and Dimensions
The LZZBJ9-35G/220 is designed for indoor switchgear installation. The supplied drawing shows a compact 220mm side-width body with a lower terminal area and different wiring diagrams for the selected current ratio. Reference dimensions include a body height of approximately 370mm, an overall side height of approximately 445mm, a base length of approximately 385mm, and a side width of approximately 220mm. 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. |
| Primary terminal layout | Check the selected current ratio and confirm whether standard, series or parallel connection is required. |
| Primary polarity | Confirm P1 / P2 direction and conductor connection before installation. |
| 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. Some configurations may include intermediate primary connection points such as C1 and C2 for series or parallel ratio wiring. Secondary terminals are arranged according to the number of metering and protection windings.
| Terminal | Function | Application Note |
|---|---|---|
| P1 / P2 | Primary terminals | Used for primary current direction and polarity reference. |
| C1 / C2 | Primary ratio connection points | Used for series or parallel primary connection where applicable. |
| 1S1 / 1S2 | First secondary winding | Usually assigned to metering or measurement circuit. |
| 2S1 / 2S2 | Second secondary winding | Usually assigned to relay protection circuit. |
| Additional S terminals | Extra metering or protection outputs | 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. |
Series and Parallel Ratio Connection
The catalogue drawing provides examples for different primary ratio wiring. For a lower current ratio, a series connection may be used. For a higher current ratio, a parallel connection may be used. The final connection method must follow the approved wiring diagram and nameplate marking.
| Connection Mode | Reference Ratio | Application Note |
|---|---|---|
| Series connection | 100/5A reference | Used when a lower primary current ratio is required. |
| Parallel connection | 200/5A reference | Used when a higher primary current ratio is required. |
| Final ratio | According to nameplate | Do not change ratio wiring without checking the wiring diagram and project setting. |
Standards and Compliance
For international product pages, the LZZBJ9-35G/220 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 GB20840.2-2014 may be retained for tender compatibility, but modern technical pages should use IEC 61869 and GB/T 20840 series as the preferred standard language.