Overview
The LZZBJ9-35G/220 is an indoor epoxy resin cast current transformer rated for 35kV-class systems, suitable for 35kV / 36kV / 40.5kV medium-voltage applications. It features a fully enclosed pillar-type design with epoxy resin casting insulation, sealing the core and secondary windings to ensure stable dielectric performance, moisture resistance, and mechanical robustness in indoor environments.
Designed for current measurement, energy metering, and relay protection in 50Hz or 60Hz AC systems, this compact 220mm-width CT supports standard accuracy classes for both metering and protection functions. It complies with international insulation coordination standards (rated insulation level 40.5/95/185kV) and is intended for use in indoor switchgear, feeder cabinets, and protection panels where space constraints favor a smaller platform over larger 270mm or 300F-class units.
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 | 50A to 1000A (catalogue); 5A–600A (terminal layout) |
| Accuracy classes | Metering: 0.2, 0.5; Protection: 5P, 10P |
| Rated output | 20VA, 30VA, or 30–50VA (depending on winding) |
| Short-time thermal current | Up to 40kA (1s, per catalogue) |
| Dynamic withstand current | Up to 100kA (peak) |
| Installation | Indoor only |
| Insulation type | Epoxy resin cast |
| Structure | Pillar-type, fully enclosed |
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.
- 35G: 35kV-class compact design version, suitable for 35kV / 36kV / 40.5kV indoor systems.
- 220: 220mm-class compact body width / structural platform.
Construction
The LZZBJ9-35G/220 employs a compact, fully enclosed epoxy resin cast structure. The primary conductor passes through the upper section, which serves as the high-voltage connection interface, while the lower portion houses the secondary terminal block and mounting base. The entire magnetic core and secondary windings are hermetically sealed within the cast-resin body, eliminating exposure to ambient humidity and contaminants. This construction ensures long-term dielectric stability, excellent tracking resistance, and reliable mechanical strength under normal operating and short-circuit conditions. The 220mm side-width profile is optimized for integration into space-constrained indoor switchgear, offering a balance between insulation performance at 40.5kV system levels and physical footprint reduction compared to wider CT platforms.
Technical Parameters
Service 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.
Technical Parameters
The LZZBJ9-35G/220 is an indoor 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 -5°C to +40°C, complies with IEC 61869 and GB/T 20840 standards, and supports primary currents from 50A to 1000A with secondary options of 1A or 5A.
| Type | Rated Primary Current (A) |
Accuracy Classes |
Rated Output (VA) | Short-Time Thermal Current (Ith)(kA) |
Rated Dynamic Current (Idyn)(kA) |
||||
|---|---|---|---|---|---|---|---|---|---|
| 0.2 0.2S |
0.5 0.5S |
10P10 5P10 |
10P15 5P15 |
10P20 5P20 |
|||||
| LZZBJ9-35G/220 | 50 | 0.2(S) / 0.5(S) 0.2(S)/10P10 0.5(S)/10P10 0.2(S)/10P15 0.5(S)/10P15 0.2(S)/10P20 0.5(S)/10P20 |
20 | 30 | 30-50 | 20 | 20 | 8/2 | 20 |
| 75 | 12/2 | 30 | |||||||
| 100 | 16/2 | 40 | |||||||
| 150 | 20/2 | 50 | |||||||
| 200 | |||||||||
| 300 | 20/4 | 50 | |||||||
| 400 | |||||||||
| 500 | |||||||||
| 600 | 31.5/4 | 80 | |||||||
| 750 | |||||||||
| 800 | |||||||||
| 1000 | 40/4 | 100 | |||||||
1. Rated output and its relative accuracy class only one alternative.
2. If user’s data go beyond the above-mentioned scopes, they may be subject to an agreement between manufacturer and purchaser.
Installation & Wiring
Installation Diagram
The LZZBJ9-35G/220 current transformer is designed for secure mounting within indoor switchgear compartments. Installation requires alignment with the approved outline drawing to ensure proper fit, terminal accessibility, and electrical clearances. The compact 220mm side-width design allows integration into standard switchgear layouts while maintaining required phase-to-phase and phase-to-ground distances for 40.5kV class equipment.
Selection & FAQs
Selection Guide
- Use the 220 platform only after a switchgear fit check. Confirm actual body width, primary-terminal geometry, base holes, secondary access and 40.5kV phase clearances against the approved outline.
- Select from the 50A–1000A catalogue range. A separate terminal-layout reference mentions 5A–600A; treat it as drawing-specific and confirm the exact ratio and wiring arrangement.
- Define measurement and protection cores as one combination. Options pair 0.2S or 0.5 with 10P10, 10P15 or 10P20; specify the required function and class for every winding.
- Allocate rated output explicitly. The page lists 20VA, 30VA and 30–50VA without an unambiguous per-class mapping, so obtain a winding schedule stating VA, secondary current and terminals per core.
- Verify fault and site conditions. Confirm ratio-specific 1-second thermal and peak dynamic current, insulation level, altitude, condensation, pollution, partial discharge and applicable IEC 61869 tests.
Frequently Asked Questions
Q1: Can this 35kV epoxy resin current transformer be used in 40.5kV systems?
Yes, it is explicitly designed for 35kV, 36kV, and 40.5kV indoor switchgear. The rated insulation level is 40.5/95/185kV. Confirm your specific system voltage with our engineering team.
Q2: When should I select the 0.2S accuracy class?
Select the 0.2S class for billing or high-precision monitoring applications. It ensures accurate measurement across varying load conditions per IEC 61869. Specify your required rated output in VA when ordering.
Q3: What are the ambient temperature limits for indoor installation?
The LZZBJ9-35G/220 operates safely in ambient temperatures ranging from -5°C to +40°C. Ensure the installation site avoids severe vibration and corrosive gases. The epoxy resin casting provides reliable protection for these indoor conditions.
Q4: How do I verify the short-time thermal current rating?
The short-time thermal current and dynamic current ratings depend on your selected primary current from 50A to 1000A. Refer to the technical parameter table for exact kA values. Request the detailed datasheet for your specific ratio.
Q5: Are these current transformers compliant with IEC standards?
Yes, this epoxy cast current transformer fully complies with IEC 61869 and GB/T 20840 standards. We provide standard factory test reports upon delivery. Contact our sales team for specific third-party certification requirements.
Q6: Can the primary and secondary current ratios be customized?
We support primary currents from 50A to 1000A with secondary options of 1A or 5A. Custom ratios and specific accuracy class combinations are available. Please provide your exact nameplate requirements for factory confirmation.
Q7: Is this an indoor or outdoor resin cast current transformer?
The LZZBJ9-35G/220 is strictly an indoor epoxy resin cast current transformer. It is optimized for indoor 35kV to 40.5kV distribution systems. The design prevents outdoor environmental degradation.