Overview
The LZZBW-35A and LZZBW-35B are outdoor single-phase current transformers rated for 35kV (40.5kV system voltage) applications. They feature a fully enclosed post-type cast-resin structure using outdoor-grade epoxy resin as the dry-type insulation medium, eliminating the need for oil and enhancing environmental resilience.
These transformers deliver high accuracy for both metering (classes such as 0.2S and 0.5) and protection (e.g., 10P or 5P), making them suitable for revenue metering, relay protection, and grid monitoring in 50Hz or 60Hz power systems. Designed to meet IEC standards, they operate reliably under harsh outdoor conditions with strong thermal and dynamic stability, moisture resistance, and anti-pollution performance.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 35kV / 40.5kV |
| Insulation level | 40.5/95/185kV (standard); 40.5/95/190kV (optional) |
| Phase | Single phase |
| Installation | Outdoor |
| Insulation medium | Epoxy resin, dry-type |
| Rated secondary current | 5A or 1A |
| Metering accuracy | 0.2S, 0.5 (as specified) |
| Protection accuracy | 10P, 5P (as specified) |
| Ambient temperature range | -40°C to +40°C |
| Altitude limit | ≤ 3000m (standard) |
| Frequency | 50Hz or 60Hz |
| Application | Measurement, metering, relay protection |
Model Designation
- L: Current transformer.
- Z: Post-type / pillar-type structure.
- Z: Cast-resin insulation.
- B: With protection winding / metering and protection current transformer series.
- W: Outdoor type.
- 35: 35kV rated voltage class, normally matched with 40.5kV highest system voltage.
- A / B: Structure code indicating different secondary winding or terminal arrangements.
Construction
The LZZBW-35A and LZZBW-35B feature a fully enclosed post-type construction with outdoor-grade epoxy resin cast insulation. This dry-type design provides robust electrical insulation between the high-voltage primary conductor and the low-voltage secondary windings without the use of oil or other liquid media. The cast-resin body incorporates sheds to increase creepage distance, enhancing performance in humid, dusty, or coastal environments. The structure ensures high mechanical strength, excellent moisture resistance, and long-term anti-tracking capability. All external surfaces are designed for outdoor insulation coordination, supporting reliable operation under pollution and UV exposure. The base includes provisions for secure mounting and grounding, while secondary terminals are housed in a protected compartment to maintain signal integrity and safety.
Technical Parameters
Service Conditions
- Ambient temperature: -40°C to +40°C reference from supplied information
- Altitude: ≤ 3000m reference; higher altitude by project confirmation
- Installation environment: Outdoor vertical mounting on foundation, bracket or steel structure
- Local discharge: Should comply with applicable current transformer standards and project requirements
Technical Parameters
The LZZBW-35A and LZZBW-35B are outdoor single-phase epoxy resin cast current transformers rated for 35kV/40.5kV systems. They operate within an ambient temperature range of -40°C to +40°C and are suitable for installations up to 3000m altitude. Compliant with IEC 61869 and GB/T 20840 standards, these units support primary currents from 10A to 2000A and secondary outputs of 1A or 5A.
| Model | Rated Current Ratio (A) |
Accuracy Class (Protection/ Measurement) |
Burden (VA) |
ALF | FS | Short-Time Thermal Current |
Dynamic Current |
|---|---|---|---|---|---|---|---|
| LZZBW-35A | 10–200/5 | 0.2S / 0.2S 0.2S / 0.5 0.2S / 10P 0.5 / 10P 0.2S / 0.5 / 10P 0.2 / 0.5 / 10P |
0.2S: 10VA 0.5: 15VA 10P: 15VA |
10 / 15 / 20 | 5 (10) |
150 × I1n | 375 × I1n |
| 300/5 | 31.5kA | 80kA | |||||
| 400/5 | 31.5kA | 80kA | |||||
| 500/5 | 40kA | 100kA | |||||
| 600/5 | 0.2S: 15VA 0.5: 15VA 10P: 15VA |
10 / 15 / 20 | 50kA | 125kA | |||
| 800/5 | 63kA | 125kA | |||||
| 1000/5 | 0.2S: 15VA 0.5: 15VA 10P: 20VA |
80kA | 160kA | ||||
| 800–2000/5 | 80kA | 160kA | |||||
| LZZBW-35B | 10–200/5 | 0.2S / 0.2S / 0.5 0.2S / 0.5 / 10P 0.2S / 0.5 / 10P / 10P 0.2S / 10P / 10P / 10P |
0.2S: 10VA 0.5: 15VA 10P: 15VA |
10 / 15 / 20 | 5 (10) |
150 × I1n | 375 × I1n |
| 300/5 | 31.5kA | 80kA | |||||
| 400/5 | 31.5kA | 80kA | |||||
| 500/5 | 40kA | 100kA | |||||
| 600/5 | 0.2S: 10VA 0.5: 15VA 10P: 15VA |
50kA | 125kA | ||||
| 800/5 | 63kA | 125kA | |||||
| 1000/5 | 0.2S: 15VA 0.5: 15VA 10P: 20VA |
80kA | 160kA | ||||
| 800–2000/5 | 80kA | 160kA |
Installation & Wiring
Installation Diagram
The LZZBW-35A and LZZBW-35B outdoor single-phase current transformers are designed for pole or structure mounting using the provided bracket. Ensure secure fastening and proper alignment with the primary conductor, maintaining safe clearances as specified in local electrical codes.
Selection & FAQs
Selection Guide
- Choose A or B by required core count. A supports simpler dual/three-core arrangements, while B lists three- and four-core schemes with multiple protection outputs.
- Select the exact ratio and correct high-current group. The “800–2000/5” row overlaps 800A and 1000A entries; obtain a corrected schedule for 1200A–2000A or any intended range.
- Use detailed, not generic, VA data. The selection table documents 10VA–20VA; general references to 30VA/40VA require ratio-specific confirmation.
- Coordinate FS and ALF per core. FS 5/10 applies to measuring cores, while ALF 10/15/20 applies to 10P protection cores.
- Qualify the outdoor installation. Confirm −40°C and 3000m performance, creepage, pollution, IP, UV, icing, wind, terminal enclosure, fault duration and partial discharge.
Frequently Asked Questions
Q1: Can this 35kV outdoor current transformer be installed above 3000m altitude?
Standard models are rated for altitudes up to 3000m. For higher elevations, custom dielectric designs are required. Please contact our engineering team for project-specific confirmation.
Q2: What is the short-time thermal current rating for the LZZBW-35B?
The short-time thermal current is rated at 150 times the primary rated current (150 × I1n). The dynamic current withstand capability is 375 × I1n. Verify specific system fault levels with our technical department.
Q3: Which accuracy class combination is available for protection and measurement?
Multiple combinations are supported, including 0.2S/0.5, 0.2S/10P, and 0.2S/0.5/10P. Measurement burdens are 10VA for 0.2S and 15VA for 0.5 and 10P classes. Specify your exact secondary burden requirements during inquiry.
Q4: Are these 35kV current transformers compliant with international IEC standards?
Yes, both LZZBW-35A and LZZBW-35B models fully comply with IEC 61869 and GB/T 20840 standards. Standard test certificates are provided upon delivery. Request specific third-party certification details during the bidding phase.
Q5: Can the primary current rating be customized beyond 2000A?
Standard configurations cover primary currents from 10A to 2000A. Custom ratios exceeding 2000A are available subject to factory engineering confirmation. Please provide your exact primary and secondary current requirements for a tailored quotation.
Q6: What applications are suitable for the LZZBW-35 epoxy resin transformer?
These single-phase outdoor current transformers are designed for 35kV and 40.5kV power systems. They are ideal for outdoor vertical mounting on foundations, brackets, or steel structures. Confirm foundation load capacities prior to procurement.
Q7: How do extreme temperatures affect the outdoor CT performance?
The epoxy resin cast units operate reliably in ambient temperatures ranging from -40°C to +40°C. Local discharge levels comply with applicable current transformer standards. Contact us for extreme climate project evaluations.