Overview
The LZZBJ4-35 is a support-type, indoor current transformer designed for 35kV and 40.5kV AC power systems operating at 50Hz or 60Hz. It features a fully enclosed cast-resin structure with electrical-grade epoxy resin encapsulating the primary winding, secondary winding, and annular magnetic core.
This hermetically sealed design ensures low partial discharge, stable accuracy under temperature variation, and reliable performance in measurement, energy metering, and relay protection applications. It is intended for use in indoor switchgear, vacuum circuit breaker cabinets, and medium-voltage distribution equipment, complying with standard insulation levels of 40.5/95/185kV.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 35kV / 40.5kV |
| Rated insulation level | 40.5/95/185kV |
| Rated frequency | 50Hz or 60Hz |
| Insulation type | Epoxy resin cast-resin |
| Installation condition | Indoor |
| Structure | Support-type, fully enclosed |
| Application | Measurement, metering, relay protection |
| Rated secondary current | 5A or 1A |
| Primary current range | As per standard ratios |
| Accuracy classes | Measurement: 0.2, 0.5; Protection: 5P, 10P |
| Safety factor (Fs) | Typically ≤10 for protection cores |
| Short-time thermal withstand | Per IEC/GB standards |
Model Designation
- L: Current transformer.
- Z: Support-type / pillar-type structure.
- Z: Epoxy resin casting insulation.
- B: Current transformer with protection-class configuration option.
- J: Reinforced type / enhanced structure design.
- 4: Design sequence number.
- 35: 35kV class product platform, suitable for 35kV and 40.5kV systems.
Construction
The LZZBJ4-35 employs a compact, support-type construction with all active components—primary winding, secondary winding, and magnetic core—fully embedded within a solid epoxy resin cast body. This hermetically sealed design eliminates internal air gaps and moisture ingress, ensuring high dielectric strength and long-term insulation stability. The outer surface is smooth and hydrophobic, enhancing pollution resistance in indoor environments. Mounting is achieved via an upper flange and a lower base plate with bolt holes, allowing secure integration into switchgear assemblies. The magnetic core uses high-permeability, low-loss material to maintain accuracy across load ranges and temperature variations.
Technical Parameters
Service Conditions
- Installation: Indoor installation for 35kV / 40.5kV switchgear and distribution systems.
- Ambient temperature: -25°C to +40°C.
- Rated frequency: 50Hz or 60Hz.
- Altitude: Not more than 2000m reference.
- Ambient environment: No severe pollution, corrosive gas, explosive atmosphere or abnormal vibration beyond product design limits.
Technical Parameters
The LZZBJ4-35 is an indoor support-type epoxy resin cast current transformer designed for 35kV/40.5kV systems, featuring a rated insulation level of 40.5/95/185kV and compliance with IEC 61869 and GB/T 20840 standards. It operates at 50Hz or 60Hz, supports altitudes up to 2000m, and offers primary current ratings from 31.5A to 1600A with secondary outputs of 1A or 5A.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 10 | 0.2,0.5,0.2S | 10,15 | 6 | 15 |
| 0.5/10P10 | 10/15,15/15 | 6 | 15 | |
| 20 | 0.2 | 10,15,20 | 10 | 25 |
| 0.5 | 10,15,20 | 10 | 25 | |
| 0.2S | 10,15,20 | 10 | 25 | |
| 0.2/10P10 | 15/15 | 10 | 25 | |
| 25 | 0.2 | 10,15 | 10 | 25 |
| 0.5 | 10,15 | 10 | 25 | |
| 0.2S | 10,15 | 10 | 25 | |
| 0.2/0.5 | 10,15 | 10 | 25 | |
| 0.2/0.5 | 10/15,15/15 | 10 | 25 | |
| 30 | 0.2 | 10,15,20 | 10 | 25 |
| 0.5 | 10,15,20 | 10 | 25 | |
| 0.2S | 10,15,20 | 10 | 25 | |
| 0.2/0.2 | 10/10,10/15 | 10 | 25 | |
| 0.2S/0.5 | 10/10,10/15 | 10 | 25 | |
| 0.2/10P10 | 10/10,10/15,15/15 | 10 | 25 | |
| 0.5/10P10 | 10/10,10/15,15/15 | 10 | 25 | |
| 0.5/10P15 | 10/10,15/15 | 10 | 25 | |
| 40 | 0.2 | 10,15,20,30 | 10 | 25 |
| 0.5 | 10,15,20,30 | 20 | 50 | |
| 0.2S | 10,15,20,30 | 10 | 25 | |
| 0.2/0.2 | 10/10,15/15,20/20 | 10 | 25 | |
| 0.2S/0.5 | 10/10,15/15,20/20 | 10 | 25 | |
| 0.2/10P10,0.5/10P10 | 10/10,15/15,20/20 | 10 | 25 | |
| 0.5/10P15,0.5/10P20 | 10/10,15/15 | 10 | 25 | |
| 50,60 | 0.2 | 10,15,20,30 | 20 | 50 |
| 0.5 | 10,15,20,30 | 25 | 63 | |
| 0.2S | 10,15,20,30 | 20 | 50 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 20 | 50 | |
| 0.2/0.5,0.2S/0.5 | 10/10,15/15,20/20 | 20 | 50 | |
| 0.2/10P10,0.5/10P10 | 10/10,15/15,20/20 | 20 | 50 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,20/20 | 10 | 25 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,20/20 | 10 | 25 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 10 | 25 | |
| 75 | 0.2 | 10,15,20,30 | 31.5 | 80 |
| 0.5 | 10,15,20,30 | 31.5 | 80 | |
| 0.2S | 10,15,20,30 | 31.5 | 80 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 31.5 | 80 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 31.5 | 80 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,20/20 | 31.5 | 80 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,20/20 | 25 | 63 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,20/20 | 15 | 38 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 15 | 38 | |
| 100 | 0.2 | 10,15,20,30 | 40 | 100 |
| 0.5 | 10,15,20,30 | 40 | 100 | |
| 0.2S | 10,15,20,30 | 40 | 100 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 40 | 100 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 40 | 100 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,20/20 | 40 | 100 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,20/20 | 20 | 50 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,20/20 | 20 | 50 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 20 | 50 | |
| 0.5/10P10/10P20 | 15/15/15,15/15/20 | 20 | 50 | |
| 125 | 0.2,0.2S,0.5 | 10,15 | 40 | 100 |
| 0.2/10P10,0.5/10P10 | 15/15 | 40 | 100 | |
| 0.2/10P20,0.5/10P20 | 15/15 | 20 | 50 | |
| 150 | 0.2 | 10,15,20,30 | 50 | 125 |
| 0.5 | 10,15,20,30 | 50 | 125 | |
| 0.2S | 10,15,20,30 | 50 | 125 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 50 | 125 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 50 | 125 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,20/20 | 50 | 125 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,20/20 | 50 | 125 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,20/20 | 25 | 63 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 25 | 63 | |
| 0.5/10P10/10P20 | 15/15/15,15/15/20 | 25 | 63 | |
| 200,250 | 0.2 | 10,15,20,30 | 50 | 125 |
| 0.5 | 10,15,20,30 | 50 | 125 | |
| 0.2S | 10,15,20,30 | 50 | 125 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 50 | 125 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 50 | 125 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,20/20 | 50 | 125 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,20/20 | 31.5 | 80 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,20/20 | 31.5 | 80 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 31.5 | 80 | |
| 0.5/10P10/10P20 | 15/15/15,15/15/20 | 31.5 | 80 | |
| 300,400 | 0.2 | 10,15,20,30 | 63 | 160 |
| 0.5 | 10,15,20,30 | 63 | 160 | |
| 0.2S | 10,15,20,30 | 63 | 160 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 63 | 160 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 63 | 160 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,20/20 | 63 | 160 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,20/20 | 40 | 100 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,20/20 | 40 | 100 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 40 | 100 | |
| 0.5/10P10/10P20 | 15/15/15,15/15/30 | 40 | 100 | |
| 500,600,630 | 0.2 | 10,15,20,30 | 63 | 160 |
| 0.5 | 10,15,20,30 | 63 | 160 | |
| 0.2S | 10,15,20,30 | 63 | 160 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 63 | 160 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 63 | 160 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,15/20,30/30 | 63 | 160 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,30/30 | 63 | 160 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,30/30 | 63 | 160 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 63 | 160 | |
| 0.2/0.5/10P20 | 15/15/15,30/30/30 | 63 | 160 | |
| 0.5/10P10/10P20 | 15/15/15,30/30/30 | 63 | 160 | |
| 0.2/0.5/10P20/10P20 | 15/15/15/15 | 63 | 160 | |
| 750,800 | 0.2 | 10,15,20,30 | 80 | 200 |
| 0.5 | 10,15,20,30 | 80 | 200 | |
| 0.2S | 10,15,20,30 | 80 | 200 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 80 | 200 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 80 | 200 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,15/20,30/30 | 80 | 200 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,30/30 | 80 | 200 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,30/30 | 80 | 200 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 80 | 200 | |
| 0.2/0.5/10P20 | 15/15/15,30/30/30 | 80 | 200 | |
| 0.5/10P10/10P20 | 15/15/15,30/30/30 | 80 | 200 | |
| 0.2/0.5/10P20/10P20 | 15/15/20/20 | 80 | 200 | |
| 1000,1200,1250 | 0.2 | 10,15,20,30 | 100 | 250 |
| 0.5 | 10,15,20,30 | 100 | 250 | |
| 0.2S | 10,15,20,30 | 100 | 250 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 100 | 250 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 100 | 250 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,15/20,30/30 | 100 | 250 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,30/30 | 100 | 250 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,30/30 | 100 | 250 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 100 | 250 | |
| 0.2/0.5/10P20 | 15/15/15,30/30/30 | 100 | 250 | |
| 0.5/10P10/10P20 | 15/15/15,30/30/30 | 100 | 250 | |
| 0.2/0.5/10P20/10P20 | 15/15/30/30 | 100 | 250 | |
| 1500-2500 | 0.2 | 10,15,20,30 | 100 | 250 |
| 0.5 | 10,15,20,30 | 100 | 250 | |
| 0.2S | 10,15,20,30 | 100 | 250 | |
| 0.2/0.2,0.2S/0.2 | 10/10,15/15,20/20 | 100 | 250 | |
| 0.2/0.5,0.2S/0.5 | 10/15,15/15,20/20 | 100 | 250 | |
| 0.2/10P10,0.5/10P10 | 10/15,15/15,15/20,30/30 | 100 | 250 | |
| 0.2/10P15,0.5/10P15 | 10/10,15/15,30/30 | 100 | 250 | |
| 0.2/10P20,0.5/10P20 | 10/10,15/15,30/30 | 100 | 250 | |
| 0.2/0.5/10P10 | 15/15/15,30/30/30 | 100 | 250 | |
| 0.2/0.5/10P20 | 15/15/15,30/30/30 | 100 | 250 | |
| 0.5/10P10/10P20 | 15/15/15,30/30/30 | 100 | 250 | |
| 0.2/0.5/10P20/10P20 | 15/15/30/30 | 100 | 250 |
Installation & Wiring
Installation Diagram
The LZZBJ4-35 indoor epoxy-resin cast current transformer is installed as a complete unit within medium-voltage switchgear or circuit breaker compartments. It is secured using the upper flange and supported at the base by four M10 bolts through the mounting holes on the base plate. Ensure all dimensional clearances—such as overall height, terminal spacing, body width, and insulation distances—are verified against the approved project drawings prior to installation.
Selection & FAQs
Selection Guide
- Choose the number of physical cores first. The family spans dual measurement, three-core metering/protection and up to four protection cores; require the exact winding and terminal diagram.
- Verify the intended primary ratio. The 31.5A row is positioned anomalously and carries fault values inconsistent with adjacent lower ratios, so obtain a corrected catalogue schedule.
- Map accuracy and output per core. References are 15VA for class 0.2, 25VA for class 0.5 and 50VA for applicable 10P cores, subject to the ordered configuration.
- Apply FS to metering, not protection. The page’s FS wording is incorrect; specify metering FS separately and use ALF/class data for 10P protection cores.
- Verify altitude, fault and mounting requirements. Confirm insulation at up to 2000m, thermal duration, peak current, upper-flange loads, four M10 holes, clearances, partial discharge and test documents.
Frequently Asked Questions
Q1: What is the rated insulation level for this 35kV current transformer?
The LZZBJ4-35 features a rated insulation level of 40.5/95/185kV. It is specifically designed for 35kV and 40.5kV indoor distribution systems. Please verify your exact system voltage during inquiry.
Q2: Can this epoxy resin CT be installed at high altitudes?
Standard models support altitudes up to 2000m reference. For installations exceeding this limit or in severe pollution environments, custom design modifications are required. Contact our engineering team for altitude-specific adjustments.
Q3: Which short-circuit ratings apply to the 20A primary current version?
The 20A primary version offers a rated short-time thermal current of 10kA/1s and a dynamic current of 25kA. These parameters ensure reliable performance under fault conditions. Confirm specific burden requirements with our technicians.
Q4: How do I specify the accuracy class combination for procurement?
Available accuracy classes include 0.2, 0.5, 0.2S, and 10P10 combinations. Select the class based on your metering or protection needs per IEC 61869. Specify your exact ratio and accuracy combination for a formal quote.
Q5: Are custom primary current ratios available for the LZZBJ4-35?
Yes, primary current ratings range from 31.5A to 1600A, with secondary outputs of 1A or 5A. Standard configurations are available for immediate quoting. Provide your exact technical parameters to our sales team for customization.
Q6: Why choose epoxy resin cast construction for this 35kV CT?
The LZZBJ4-35 is a dry-type, epoxy resin cast current transformer. This support-type design eliminates oil leakage risks for indoor 35kV switchgear. Request the specific material certification during your procurement process.