Product Overview
The LZX6-35W outdoor epoxy resin cast current transformer is a high-voltage dry-type instrument transformer designed for 35kV / 40.5kV class outdoor power systems. It is used for current measurement, energy metering and relay protection in AC power systems with rated frequency of 50Hz or 60Hz. The product adopts an outdoor epoxy cast-resin fully enclosed structure, providing stable insulation performance, mechanical strength and weather resistance for exposed service conditions.
This product should be positioned as a 35kV outdoor high-voltage epoxy CT for substations, outdoor feeder bays, distribution transformer protection and industrial grid connection points. Compared with oil-immersed outdoor CTs, the LZX6-35W is oil-free, compact and easier to maintain. Compared with 20kV / 24kV outdoor epoxy CTs, it is designed for a higher insulation platform with 40.5/95/185kV insulation level and larger outdoor creepage / clearance requirements.
Product Type
| Item | Specification |
|---|---|
| Product name | Outdoor Epoxy Resin Cast Current Transformer |
| Model | LZX6-35W |
| Installation condition | Outdoor |
| Structure | High-voltage outdoor dry-type epoxy resin cast structure |
| Application | Current measurement, energy metering and relay protection |
| Voltage class | 35kV / 40.5kV class power system |
| Rated insulation level | 40.5/95/185kV |
| Rated frequency | 50Hz or 60Hz |
| Rated secondary current | 5A or 1A |
| Design focus | Outdoor insulation, metering accuracy and protection reliability |
Model Explanation
- L: Current transformer.
- Z: Pillar-type / post-type structure reference.
- X: Outdoor high-voltage current transformer structure series reference.
- 6: Design sequence or structure platform code.
- 35: 35kV rated voltage class, normally used in 35kV / 40.5kV equipment platforms.
- W: Outdoor type.
- 5A or 1A: Rated secondary current option.
- Accuracy class: Metering classes such as 0.2S, 0.2, 0.5S, 0.5, and protection classes such as 5P / 10P according to project requirement.
Product Positioning
The LZX6-35W should be written as a 35kV outdoor epoxy resin CT for high-voltage distribution and substation service. Its core difference is the higher insulation level and outdoor dry-type cast-resin structure. It is not a compact indoor switchgear CT, and it is not an oil-immersed CT. The best positioning is an oil-free outdoor CT for projects that require 35kV insulation coordination, reliable metering output and protection-class secondary windings.
| Positioning Point | Technical Meaning | Website Expression |
|---|---|---|
| 35kV / 40.5kV platform | Higher voltage insulation platform than 24kV outdoor CTs | Designed for 35kV outdoor substations and feeder systems |
| Outdoor epoxy cast-resin body | Dry-type fully enclosed insulation without transformer oil | Oil-free outdoor CT with reduced leakage and maintenance risk |
| 40.5/95/185kV insulation level | Power-frequency and lightning impulse withstand capability | Suitable for 35kV class insulation coordination |
| Metering + protection | Measurement and relay protection secondary outputs can be configured | Supports energy metering, current measurement and fault protection |
| Multiple wiring schemes | Single ratio, tapped ratio and two-secondary-winding configurations | Flexible terminal marking for metering and protection circuits |
Applications
- 35kV outdoor substations and distribution feeder bays
- 35kV / 40.5kV class outdoor current measurement points
- Energy metering and utility billing measurement circuits
- Relay protection for feeders, transformers and capacitor banks
- Industrial power distribution systems and grid connection projects
- Renewable energy substations for wind, solar and storage systems
- Projects requiring oil-free outdoor high-voltage instrument transformers
Features
- 35kV outdoor insulation platform: Rated insulation level of 40.5/95/185kV supports 35kV / 40.5kV class power systems.
- Dry-type epoxy resin casting: Fully enclosed oil-free structure reduces leakage risk and simplifies outdoor maintenance.
- High mechanical strength: Pillar-type structure is suitable for outdoor mounting, conductor connection and mechanical stress from field wiring.
- Metering and protection accuracy: Supports 0.2S / 0.2 / 0.5S / 0.5 metering classes and 5P / 10P protection classes by project design.
- Flexible secondary configuration: Single ratio, tapped ratio and two-secondary-winding arrangements can be selected according to system requirements.
- Outdoor service capability: Designed for humidity, UV exposure, dust and temperature variation in outdoor installations.
Operating Principle
The LZX6-35W current transformer converts high primary current in a 35kV circuit into a standardized low secondary current, normally 5A or 1A. The secondary output is connected to meters, protection relays, monitoring devices or SCADA input circuits. The epoxy resin cast body provides insulation between the high-voltage primary circuit and low-voltage secondary circuit.
For metering, the CT must maintain its ratio error and phase displacement within the selected accuracy class and burden. For relay protection, the protection winding must provide adequate output during fault-current conditions. Therefore, current ratio, accuracy class, rated output, short-time thermal current and dynamic current should be selected as one complete engineering set.
Technical Data
| Parameter | Specification |
|---|---|
| Model | LZX6-35W |
| Product type | Outdoor epoxy resin cast current transformer |
| Rated voltage class | 35kV / 40.5kV class |
| Rated insulation level | 40.5/95/185kV |
| Rated frequency | 50Hz or 60Hz |
| Rated secondary current | 5A or 1A |
| Rated primary current | 5A to 1250A reference range according to supplied catalogue data |
| Accuracy class | 0.2S / 0.2 / 0.5S / 0.5 for metering; 5P or 10P for protection |
| Rated output | 20VA, 30VA, 40VA, 50VA or 60VA depending on ratio and accuracy class |
| Ambient temperature | -25°C to +55°C reference from supplied catalogue data |
| Installation | Outdoor |
| Applicable standards | IEC 61869-1, IEC 61869-2, GB/T 20840.1, GB/T 20840.2; project-specific requirements by agreement |
Selection Table
The following table is reorganized from the supplied catalogue data and optimized for website display. Long headers are split into multiple lines for better responsive layout.
| Configuration | Rated Primary Current (A) |
Accuracy Class Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current |
Rated Dynamic Current |
|---|---|---|---|---|---|
| Single ratio | 5–300 | 0.2S 0.2 0.5S 0.5 |
20 / 30 / 20 / 40 | 80 × I1n | 200 × I1n |
| 400 | 20 / 30 / 20 / 40 | 31.5kA | 100kA | ||
| 500 | 30 / 40 / 40 / 50 | 45kA | 112.5kA | ||
| 600 | 50 / 50 / 60 / 60 | 63kA | 160kA | ||
| 750–800 | 50 / 50 / 60 / 60 | 80kA | 200kA | ||
| 1000–1250 | 50 / 50 / 60 / 60 | 100kA | 250kA | ||
| Tapped ratio / multiple ratio | 5–300 | 0.2S 0.2 0.5S 0.5 |
10 / 15 / 20 / 20 | 80 × I1n | 200 × I1n |
| 400 | 20 / 30 / 40 / 50 | 31.5kA | 100kA | ||
| 500 | 20 / 30 / 40 / 40 | 45kA | 112.5kA | ||
| 600 | 20 / 30 / 50 / 40 | 63kA | 160kA | ||
| 750–800 | 30 / 40 / 40 / 50 | 80kA | 200kA | ||
| 1000–1250 | 30 / 40 / 40 / 50 | 100kA | 250kA |
Note: The table is for preliminary selection. Final current ratio, rated burden, accuracy class, winding quantity, short-time thermal current, dynamic current and terminal arrangement shall be confirmed according to the nameplate, approved drawing and factory test report.
Normal Operating Conditions
| Parameter | Value |
|---|---|
| Installation place | Outdoor |
| Rated frequency | 50Hz or 60Hz |
| Ambient temperature | -25°C to +55°C reference |
| Altitude | ≤ 1000m under standard service conditions; higher altitude by agreement |
| 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 condition | No severe shock, abnormal vibration or mechanical stress beyond design limits |
Installation and Dimensions
The LZX6-35W should be installed vertically on a stable outdoor steel structure, concrete foundation, substation bracket or pole-mounted support. The product has a high-voltage outdoor bushing structure, so phase-to-phase and phase-to-ground clearance must be checked before installation. The secondary terminal box is arranged at the lower body position for wiring, testing and maintenance.
| Dimension / Installation Item | Reference Value / Recommended Check Point |
|---|---|
| Overall height | Approx. 825 ± 5mm reference from drawing |
| Body height | Approx. 711 ± 5mm reference |
| Front base width | Approx. 330mm reference |
| Base depth | Approx. 250mm reference |
| Side base width | Approx. 210–260mm reference from drawing |
| Primary terminals | Top P1 / P2 primary terminal arrangement |
| Secondary terminal box | Lower front terminal box for secondary wiring |
| Mounting check | Confirm base hole spacing, support strength, electrical clearance, grounding and cable outlet before installation. |
Windings & Terminal Marking
The LZX6-35W platform can be supplied with different secondary wiring arrangements, including single ratio, tapped ratio and two-secondary-winding configurations. The final terminal marking must follow the approved wiring diagram and nameplate.
| Terminal Marking | Function | Application Note |
|---|---|---|
| P1 / P2 | Primary terminals | Used for primary current direction and polarity reference. |
| S1 / S3 | Single-ratio secondary winding reference | Used where one secondary output is required. |
| S1 / S2 / S3 | Tapped secondary winding | Used for multiple transformation ratios or tapped output configuration. |
| 1S1 / 1S2 | First secondary winding | Usually assigned to metering or current measurement. |
| 2S1 / 2S2 | Second secondary winding | Usually assigned to relay protection or backup protection. |
| Grounding point | Secondary / base grounding reference | One point of the secondary circuit and the CT base should be grounded according to project practice. |
Standards and Compliance
For current international documentation, the LZX6-35W should be specified according to IEC 61869-1 and IEC 61869-2. For GB-based projects, GB/T 20840.1 and GB/T 20840.2 can be used. The supplied catalogue information references GB20840.1-2010 and GB20840.2-2014. Final compliance scope should be confirmed according to the order, technical agreement and routine test plan.
Safety Notes
- Confirm the 35kV / 40.5kV voltage class, rated insulation level, current ratio, secondary current, accuracy class and rated burden before installation.
- Check P1 / P2 polarity and secondary terminal marking before connecting meters, relays or test devices.
- Confirm outdoor electrical clearance, support strength, conductor connection angle and mechanical load before energizing.
- Ground the CT base and one point of the secondary circuit according to the substation grounding design.
- The CT secondary circuit must not be open-circuited while primary current is flowing.
- Before disconnecting meters, relays or test equipment, short-circuit the secondary circuit with an approved shorting device.
- Seal the secondary terminal box after wiring to reduce moisture ingress and maintain outdoor reliability.
- Installation and commissioning shall be performed by qualified high-voltage electrical personnel.