Overview
The LZZBW2-35 / LZZBJ71-35W GY is a fully enclosed, pillar-type outdoor current transformer designed for 33kV, 35kV, and 40.5kV power systems. It uses outdoor-grade epoxy resin cast insulation to encapsulate the primary winding, secondary winding, and magnetic core, ensuring high mechanical strength and stable dielectric performance in harsh environments.
This dry-type CT supports current measurement, energy metering, and relay protection in AC networks operating at 50Hz or 60Hz. It is suitable for utility feeders, outdoor substations, renewable energy collection lines, pole-mounted metering, and industrial distribution systems. The design meets standard insulation coordination requirements for outdoor service with a rated insulation level of 40.5/95/185kV.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 33kV / 35kV / 40.5kV |
| Rated insulation level | 40.5/95/185kV |
| Rated frequency | 50Hz or 60Hz |
| Rated secondary current | 5A or 1A |
| Insulation type | Outdoor epoxy resin cast |
| Installation condition | Outdoor |
| Structure | Fully enclosed pillar-type |
| Application | Measurement, metering, protection |
| Ambient temperature range | -5°C to +40°C (standard) |
| Pollution withstand | Per project specification |
| Altitude suitability | Standard; high-altitude correction available |
| UV and humidity resistance | Designed for outdoor exposure |
Model Designation
- L: Current transformer.
- Z: Pillar-type / post-type structure.
- Z: Epoxy resin cast insulation.
- B: Series with metering and protection windings.
- J: Reinforced insulation or enhanced design.
- 71: Structural platform code.
- 35: 35kV class for 33kV–40.5kV systems.
- W: Outdoor type.
- GY: Project-specific variant for reinforced outdoor use or special terminal requirements.
Construction
The LZZBJ71-35 / LZZBJ71-35W GY features a monolithic, fully enclosed pillar-type construction with all active components—primary winding, secondary winding, and magnetic core—permanently sealed within a single outdoor-grade epoxy resin casting. This oil-free design eliminates leakage risks and reduces maintenance needs compared to oil-immersed alternatives. The resin compound provides excellent tracking resistance, UV stability, and hydrophobic surface properties suitable for long-term outdoor exposure. The housing integrates top-mounted primary terminals and a lower front-access secondary terminal box, facilitating secure connections while maintaining IP-rated protection against environmental ingress. The creepage distance and insulation coordination are engineered to meet or exceed standard requirements for 40.5kV-class outdoor applications under typical pollution conditions.
Technical Parameters
Service Conditions
- Ambient temperature: -5°C to +40°C reference; special outdoor service by agreement
- Altitude: ≤ 1000m
- Atmospheric condition: No severe pollution, corrosive gas or explosive atmosphere beyond design limits
- Outdoor exposure: Suitable for humidity, UV exposure and tracking-resistant insulation applications
- Installation place: Outdoor
Technical Parameters
The LZZBJ71-35W GY is an outdoor epoxy resin cast current transformer designed for 33kV/35kV/40.5kV systems with a rated insulation level of 40.5/95/185kV. It operates at 50Hz or 60Hz, supports primary currents from 15A to 1000A, and complies with IEC 61869-1, IEC 61869-2, GB/T 20840.1, and GB/T 20840.2 standards.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1S) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 15 | 0.2S/0.5 0.2(0.5)/10P10 0.2(0.5)/10P15 10P10/10P10 10P15/10P15 0.2S/0.5/10P20/10P20 |
30/50 30/50 30/20 50/50 20/20 20/20/20/20 |
3 | 7.5 |
| 20 | 4 | 10 | ||
| 30 | 6 | 15 | ||
| 40 | 8 | 20 | ||
| 50 | 10 | 25 | ||
| 75 | 15 | 37.5 | ||
| 100 | 21 | 52.5 | ||
| 150 | 31.5 | 78.75 | ||
| 200 | 45 | 112.5 | ||
| 300 | ||||
| 400 | 0.2S/0.5 0.2(0.5)/10P10 0.2(0.5)/10P15 0.2(0.5)/10P20 10P10/10P10 10P15/10P15 0.2S/0.5/10P20/10P20 |
50/50 50/30 50/20 50/30 50/50 30/30 20/20/20/20 |
63 | 157.5 |
| 500 | ||||
| 600 | ||||
| 800 | ||||
| 1000 | 80 | 200 |
Installation & Wiring
Installation Diagram
The LZZBJ71-35W GY outdoor epoxy-resin cast current transformer is installed on a stable steel bracket, pole-mounted support, mounting plate, or substation foundation. Primary terminals (P1/P2) are located at the top for line connection, while the secondary terminal box is positioned at the lower front for wiring access.
Selection & FAQs
Selection Guide
- Define the GY variant from project documents. Its reinforced outdoor or special-terminal meaning is not quantified; obtain the GY outline, terminal enclosure and material specification.
- Select the 15A–1000A ratio and core arrangement. Options include dual measurement, measurement/protection, dual protection and a selected four-function metering/protection scheme.
- Resolve per-core VA allocation. Several multi-function rows have fewer VA values than accuracy labels, so require a winding sequence, terminal diagram and guaranteed output per physical core.
- Specify the complete outdoor environment. State minimum creepage, pollution severity, IP rating, UV, tracking/erosion, rain, condensation, salt fog, wind, icing and site temperature.
- Verify mechanical and fault coordination. Confirm foundation or pole loads, terminal forces, conductor tension, thermal duration, peak current, grounding, altitude and IEC 61869 outdoor tests.
Frequently Asked Questions
Q1: What voltage systems is this outdoor current transformer rated for?
It is designed for 33kV, 35kV, and 40.5kV systems with a rated insulation level of 40.5/95/185kV. Please confirm specific system requirements with our engineering team before ordering.
Q2: Which accuracy class combination is available for metering and protection?
Multiple combinations are available, including 0.2S/0.5 for metering and 10P10 for protection. Specify your exact core requirements during the inquiry process to ensure proper selection.
Q3: How does the short-circuit thermal current rating vary by primary current?
The rated short-time thermal current ranges from 3kA for 15A primary up to higher values for larger currents. Refer to the parameter table or contact us for exact project ratings.
Q4: Can this epoxy resin cast CT withstand severe outdoor weather conditions?
Yes, it features tracking-resistant insulation suitable for outdoor humidity and UV exposure. Ensure the installation site has no severe pollution or corrosive gases beyond standard design limits.
Q5: Are specific compliance certificates provided for this 35kV current transformer?
The transformer fully complies with IEC 61869-1, IEC 61869-2, GB/T 20840.1, and GB/T 20840.2 standards. Request the specific type test reports from our quality department during procurement.
Q6: When should buyers request custom service conditions for extreme environments?
Standard limits are ≤1000m altitude and -5°C to +40°C ambient temperature. Special outdoor service conditions for extreme environments are available by agreement; contact our sales team for details.