Overview
The LZZW-35 Epoxy Resin Cast Current Transformer is a precision electromagnetic device engineered for accurate current measurement, energy metering, and relay protection in 35 kV class outdoor AC power systems. It operates on electromagnetic induction principles to deliver galvanically isolated secondary current signals proportional to the primary current.
Its fully enclosed epoxy resin cast structure ensures exceptional weather resistance, UV stability, and high insulation performance, making it ideal for harsh outdoor environments including high-pollution zones.
Key Ratings Snapshot
| Item | Specification |
|---|---|
| System voltage class | 35 kV class |
| Rated frequency | 50 Hz or 60 Hz |
| Rated secondary current | 5 A |
| Accuracy classes | 0.2 / 0.2S / 0.5 / 0.5S, 10P10 / 10P15 |
| Rated burden | 10-15 VA typical |
| Burden power factor | cos phi = 0.8 (lagging) |
| Short-circuit withstand | Ith (1 s): 13.5-40 kA; Idyn (peak): 34-100 kA |
| Insulation level | 40.5 / 95 / 185 kV (Um / Up / Ud) |
| Installation type | Outdoor, post-mounted |
| Applicable standards | IEC 61869-1/-2; GB/T 20840.1/.2; GB 1208-2006 |
Model Designation
- L: Current transformer (CT)
- Z: Post (pillar) type mounting structure
- Z: Cast-resin (epoxy) insulated, fully enclosed structure
- W: Outdoor installation type
- 35: Voltage class (kV)
Construction
The LZZW-35 features a one-piece, fully enclosed epoxy resin cast construction that provides superior moisture resistance, mechanical strength, and long-term outdoor durability. The post-type design ensures adequate electrical clearance and creepage distances, even in pollution level IV environments. Internal magnetic cores and windings are hermetically sealed within the epoxy matrix, eliminating risks of contamination or moisture ingress throughout the service life.
High-permeability toroidal cores ensure excellent linearity and accuracy across the operating range. The weatherproof epoxy formulation includes UV stabilizers for extended outdoor exposure without degradation, supporting reliable operation from -25 degC to +40 degC ambient temperatures.
Technical Parameters
Service Conditions
- Installation environment: Outdoor installation with appropriate weatherproofing
- Altitude: Not exceeding 1000 m above sea level (higher altitude configurations available upon specification)
- Ambient temperature: -25 degC to +40 degC (extended range to -40 degC available)
- Relative humidity: Daily average <= 95%, monthly average <= 90%
- Environmental conditions: Pollution level IV capability; free from corrosive gases, explosive media, or severe mechanical vibration
- Seismic resistance: Suitable for seismic intensity zones per applicable codes
Technical Data
| Rated Primary Current (A) |
Rated Output (VA) | Short-Time Thermal Current (kA/s) |
Rated Dynamic Current (kA) |
||||
|---|---|---|---|---|---|---|---|
| 0.2s | 0.2 | 0.5 | 10p10 | 10p15 | |||
| 5-100 | 10 | 10 | 15 | 15 | 10 | 13.5 | 34 |
| 150 | 10 | 10 | 15 | 15 | 10 | 18 | 45 |
| 200 | 10 | 10 | 15 | 15 | 10 | 27 | 67.5 |
| 300 | 10 | 10 | 15 | 15 | 10 | 30 | 75 |
| 400 | 10 | 10 | 15 | 15 | 10 | 36 | 90 |
| 500 | 10 | 10 | 15 | 15 | 10 | 40 | 100 |
Installation & Wiring
Installation Diagram
Proper installation requires qualified personnel following local electrical codes and utility standards. Primary conductors must be securely mounted with adequate mechanical support and electrical clearance. Secondary wiring should use weather-resistant cable with strain relief, and the grounding terminal must connect to the station ground grid. Maintain specified creepage distances for outdoor pollution environments.
Outline Dimensions
| Parameter | Value |
|---|---|
| Total height | As per rated current (request drawing) |
| Base mounting hole pattern | Standard M16 or as specified |
| Primary terminal spacing | Per IEC 61869 clearance requirements |
| Secondary terminal block | Weather-resistant, IP54 rated |
| phi Mounting bolt holes | phi 18 mm typical |
Selection & FAQs
Selection Guide
- Select within the detailed 5A–500A range. Any higher ratio or enhanced fault duty requires a separate factory schedule; the published secondary is fixed at 5A.
- Choose protection class and burden together. 10P10 is listed at 15VA while 10P15 is only 10VA, so calculate relay, cable, terminal and test-block burden.
- Verify Class IV creepage numerically. The page claims high-pollution capability but gives no millimetre value; specify minimum creepage and the applicable pollution standard.
- Confirm cold and environmental options. Standard operation is −25°C; −40°C, seismic, UV, tracking, salt fog, rain and condensation performance require project-specific evidence.
- Approve outdoor mechanical interfaces. Confirm exact outline, primary terminals, M16 fixing specification, typical Ø18 holes, IP54 terminal enclosure, support loads, grounding and fault-current duration.
Frequently Asked Questions
Q1: Can this 35kV current transformer be installed outdoors?
Yes, it is designed for outdoor installation with appropriate weatherproofing. It operates in ambient temperatures from -25°C to +40°C and withstands pollution level IV. Contact us for extended temperature range options.
Q2: Which accuracy class is suitable for protection relays?
Select the 10P10 or 10P15 accuracy classes for protection applications. These classes ensure reliable performance during fault conditions with rated outputs of 15 VA. Specify your exact protection requirements during ordering.
Q3: What is the short-time thermal current rating?
The rating depends on the primary current, ranging from 13.5 kA/s for 5-100A to 18 kA/s for 150A. Rated dynamic currents are 34 kA and 45 kA respectively. Confirm your specific fault level requirements with our engineering team.
Q4: Can the altitude specification be customized for high elevations?
Standard models are rated for altitudes not exceeding 1000 m above sea level. Higher altitude configurations are available upon specific request. Please provide your exact site elevation for factory verification.
Q5: What factory tests are performed before shipment?
Standard routine tests are conducted to ensure compliance with applicable international standards. Specific type tests or third-party certifications are subject to confirmation. Contact our sales team for detailed test reports.
Q6: Where is this casting resin current transformer typically applied?
It is primarily used in 35kV outdoor power distribution and substations for current measurement and protection. The epoxy resin casting provides excellent insulation and seismic resistance. Request our application guide for specific substation designs.
Q7: How does the transformer handle high humidity environments?
The unit is designed to withstand daily average relative humidity up to 95% and monthly averages up to 90%. Ensure the installation environment remains free from corrosive gases. Confirm specific environmental hazards with our technical support.
Q8: Are you the direct manufacturer of this 35kV CT?
Yes, we are the direct manufacturer of the LZZW-35KV casting resin current transformer. We provide full factory support, custom engineering, and direct supply for international projects. Contact us for factory audit details.