Overview
The LZX-10, LZZ-10, and LZZW-10 are 10 kV class cast-resin current transformers designed for medium-voltage AC power systems. These devices utilize a fully enclosed epoxy cast-resin insulation structure, ensuring reliable dielectric performance and long-term stability in both indoor and outdoor switchgear environments.
Offering metering accuracy classes of 0.2S, 0.2, and 0.5, along with protection classes 10P10 and 10P15, they support applications in energy metering, protective relaying, and SCADA current acquisition. The units comply with international standards including IEC 61869-1/-2, GB/T 20840.1/.2, and optionally IEEE C57.13, making them suitable for global distribution networks operating at 50 Hz or 60 Hz.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 10 kV |
| Rated frequency | 50 Hz or 60 Hz |
| Rated secondary current | 5 A (1 A optional) |
| Metering accuracy classes | 0.2S, 0.2, 0.5 |
| Protection accuracy classes | 10P10, 10P15 |
| Rated burden | 10 VA, 15 VA (per core) |
| Burden power factor | cosφ = 0.8 (lagging) |
| Short-circuit withstand (Ith) | 13.5 – 45 kA (1 s) |
| Dynamic withstand (Idyn) | 34 – 112.5 kA (peak) |
| Insulation level (Um/Up/Ud) | 12/42/75 kV |
| Applicable standards | IEC 61869-1/-2; GB/T 20840.1/.2; IEEE C57.13 (optional) |
Model Designation
- L: Current transformer (CT)
- Z: Post (support/pillar) type structure
- X / Z / ZW: Variant code indicating structural and environmental configuration differences
- 10: Voltage class (10 kV)
Construction
The LZX-10, LZZ-10, and LZZW-10 feature a post-type configuration with fully enclosed epoxy cast-resin insulation, providing excellent moisture resistance, contamination immunity, and mechanical rigidity. The toroidal magnetic core is constructed from high-permeability silicon-steel laminations to ensure low losses and precise accuracy under specified burden conditions. Primary current flows through a central window (P1 to P2), while secondary windings (1S1/1S2, 2S1/2S2) deliver isolated, proportional output signals for metering and protection circuits. The cast-resin encapsulation ensures stable dielectric performance over time and supports safe operation in harsh environments when configured per variant-specific IP ratings and creepage distances.
Technical Parameters
Service Conditions
- Installation environment: Indoor and outdoor installation
- Altitude: ≤ 1000 m above sea level (higher altitude requires insulation correction and engineering confirmation)
- Ambient temperature: −25 °C to +40 °C
- Relative humidity: ≤ 90% at +20 °C reference temperature
- Environmental conditions: Free from explosive/flammable media; avoid long-term severe vibration or mechanical shock; for outdoor projects, confirm IP rating and pollution requirements
- Pollution level: LZZW-10 is intended for higher pollution conditions (creepage distance per drawings/nameplate)
Technical Parameters
The LZX-10, LZZ-10, and LZZW-10 are 10 kV cast-resin current transformers designed for indoor and outdoor use within an ambient temperature range of −25 °C to +40 °C and altitudes up to 1000 m. They comply with standard accuracy classes for metering and protection applications and support primary current ratings from 5 A to 400 A.
Current Transformer Data
| Rated Primary Current (A) |
0.2S (VA) |
0.2 (VA) |
0.5 (VA) |
10P10 (VA) |
10P15 (VA) |
Short-Time Thermal Current (kA/1s) |
Dynamic Current (kA) |
|---|---|---|---|---|---|---|---|
| 5 – 100 | 10 | 10 | 10 | 15 | 15 | 13.5 | 34 |
| 150 | 10 | 10 | 10 | 15 | 15 | 18 | 45 |
| 200 | 10 | 10 | 10 | 15 | 15 | 27 | 67.5 |
| 300 | 10 | 10 | 10 | 15 | 15 | 36 | 90 |
| 400 | 10 | 10 | 10 | 15 | 15 | 45 | 112.5 |
Installation & Wiring
Installation Diagram
The LZX-10, LZZ-10, and LZZW-10 10kV cast-resin current transformers are installed by securing the unit through the provided mounting holes onto a support structure or switchgear frame. The primary conductor (busbar or bolted terminal) passes through the central aperture, with connection details determined by the specific switchgear layout and variant drawing. Ensure adequate clearance and creepage distances are maintained. Secondary terminals must be wired with anti-loosening measures, provisions for maintenance shorting, and one-point grounding as per project specifications.
Selection & FAQs
Selection Guide
- Choose LZX, LZZ or LZZW from the variant drawing. LZZW is identified for higher pollution, while the exact structural differences between X and Z are not quantified; compare dimensions, terminals, IP rating and creepage.
- Select the primary ratio from 5A–400A. Match feeder loading and measurement range, then use the ratio-specific 1-second thermal and peak dynamic ratings to check the switchgear fault level.
- Specify the required accuracy and burden. Measurement classes 0.2S, 0.2 and 0.5 are listed at 10VA, while 10P10 and 10P15 protection classes are listed at 15VA per applicable core.
- Confirm 1A versions separately. The detailed selection table is based on the standard 5A secondary; for 1A, verify ratio, output, accuracy, protection class, terminals and fault data.
- Qualify any outdoor or polluted-site installation. Confirm enclosure/IP performance, UV and weathering resistance, condensation control, pollution class, actual creepage, −25°C operation, mounting and 12/42/75kV insulation.
Frequently Asked Questions
Q1: Which accuracy class is required for revenue metering?
Select the 0.2S accuracy class for revenue billing applications. This ensures high precision across varying load conditions. Confirm specific VA burden requirements with our engineering team.
Q2: Can the LZZW-10 model be installed in severe outdoor pollution?
Yes, the LZZW-10 is specifically designed for higher pollution outdoor conditions. It features an extended creepage distance to prevent flashovers. Verify the exact pollution level and IP rating for your site.
Q3: What is the maximum short-time thermal current rating?
The short-time thermal current depends on the selected primary current rating. Ratings range from 5 A to 400 A with varying kA/1s limits. Check the detailed technical table or contact us for specific values.
Q4: How do we order these transformers for high-altitude projects?
Standard models are rated for altitudes up to 1000 m. Installations above this limit require insulation correction and engineering adjustments. Submit your exact site altitude for factory confirmation.
Q5: Are factory acceptance tests provided before shipment?
Yes, standard routine tests are conducted prior to dispatch. This ensures compliance with all listed technical parameters and accuracy classes. Request the specific test certificate format during your initial inquiry.
Q6: What applications are these 10kV cast-resin current transformers used for?
These 10kV cast-resin current transformers are used for power distribution systems. They support both metering and protection applications in indoor and outdoor switchgear. Confirm your specific application scenario with our technical sales team.
Q7: Why is the ambient temperature range restricted to -25°C to +40°C?
This temperature range ensures optimal performance of the cast-resin insulation. It maintains dielectric strength and prevents material degradation under standard conditions. Consult our engineers if your site experiences extreme environmental temperatures.