Overview
The LZZBJW-10/185/4S is an outdoor epoxy cast-resin current transformer designed for 10 kV, 11 kV and 12 kV class medium-voltage systems operating at 50 Hz or 60 Hz. It features a fully enclosed weather-resistant body with shed-type creepage ribs and provides standardized 5 A or 1 A secondary output for accurate current transformation.
This CT supports metering (0.2S/0.5), measurement and protection (5P10–5P30) functions in exposed outdoor environments such as substations, pole-mounted units and feeder bays. Its design meets insulation coordination requirements of 12/42/75 kV and ensures reliable performance under rain, humidity and surface pollution conditions.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage | 10 kV / 11 kV / 12 kV |
| Insulation level | 12/42/75 kV |
| Rated frequency | 50 Hz / 60 Hz |
| Secondary current | 5 A or 1 A |
| Secondary configuration | 4S (four-secondary) |
| Metering accuracy | 0.2S, 0.5 |
| Protection accuracy | 5P10, 5P15, 5P20, 5P30 |
| Installation type | Outdoor |
| Insulation material | Epoxy cast-resin |
| Structure | Shed-type creepage ribs |
| Primary terminal | Top-mounted |
| Application | Metering, protection, monitoring |
Technical Parameters
Service Conditions
- Installation location: outdoor medium-voltage power system
- System voltage: 10 kV, 11 kV and 12 kV class networks
- Rated frequency: 50 Hz / 60 Hz
- Rated secondary current: 5 A or 1 A
- Ambient temperature: -25°C to +40°C
- Installation environment: shall be reviewed for pollution level, rain exposure, humidity, altitude, wind load and mechanical terminal stress.
- Special environmental considerations: For coastal, high-humidity, heavy-pollution or high-altitude applications, creepage distance and insulation coordination must be confirmed by technical agreement.
Technical Parameters
The LZZBJW-10/185/4S is an outdoor epoxy cast-resin current transformer designed for 10–12 kV class systems. It operates within an ambient temperature range of -25°C to +40°C and is suitable for standard and demanding outdoor environments including high humidity, pollution, and elevated altitudes when specified. Compliant with GB 20840.1-2010 and GB 20840.2-2014, it supports primary currents from 10 A to 2000 A with multiple accuracy and output configurations.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Short-Time Thermal Current (kA/1s) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 10–40 | 0.2S / 0.5 / 5P10 0.2S / 0.5 / 5P15 0.2S / 0.5 / 5P20 0.2S / 0.5 / 5P30 0.2S / 0.5 / 5P10 / 5P10 0.2S / 0.5 / 5P15 / 5P15 0.2S / 0.5 / 5P20 / 5P20 0.2S / 0.5 / 5P30 / 5P30 |
20 / 20 / 100 20 / 20 / 60 20 / 20 / 40 20 / 20 / 25 20 / 20 / 40 / 40 20 / 20 / 30 / 30 20 / 20 / 20 / 20 20 / 20 / 10 / 10 |
150 × I1n (A) | 375 × I1n (A) |
| 50–100 | 200 × I1n (A) | 500 × I1n (A) | ||
| 150–250 | 32 | 80 | ||
| 300–400 | 50 | 125 | ||
| 500–600 | 63 | 160 |
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Short-Time Thermal Current (kA/1s) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 750–800 | 0.2S / 0.5 / 5P10 0.2S / 0.5 / 5P15 0.2S / 0.5 / 5P20 0.2S / 0.5 / 5P30 0.2S / 0.5 / 5P10 / 5P10 0.2S / 0.5 / 5P15 / 5P15 0.2S / 0.5 / 5P20 / 5P20 0.2S / 0.5 / 5P30 / 5P30 |
30 / 30 / 120 30 / 30 / 80 30 / 30 / 50 30 / 30 / 30 30 / 30 / 50 / 50 30 / 30 / 30 / 30 30 / 30 / 25 / 25 30 / 30 / 15 / 15 |
80 | 200 |
| 1000–2000 | 100 | 250 |
Note:
If user’s data go beyond the above-mentioned scopes, they may be subject to an agreement between manufacturer and purchaser.
Installation & Wiring
Installation Diagram
The LZZBJW-10/185/4S is installed outdoors on a support structure using the base mounting holes as specified in the approved outline drawing. The primary conductor passes through the center of the transformer and connects to the top terminals, with layout varying by rated primary current range (5 A < I1n < 800 A, 1000 A < I1n < 1600 A, or 1600 A < I1n < 2000 A). The secondary terminal box is located at the base and must be sealed against moisture ingress after wiring.
Selection & FAQs
Selection Guide
- Confirm the 10kV, 11kV, or 12kV system class, 12/42/75kV insulation level, frequency, and outdoor conditions.
- Select the 10A–2000A primary ratio and choose a 1A or 5A secondary to suit relay, meter, and cable requirements.
- Assign all four secondary windings by function, with accuracy class and VA burden specified separately for each.
- Verify Ith and Idyn for the selected ratio against the maximum prospective fault duty.
- Confirm the final outline drawing, conductor arrangement, base mounting, terminal sealing, grounding, and creepage requirement.
Frequently Asked Questions
Q1: Which system voltages are supported by this outdoor current transformer?
It supports 10 kV, 11 kV, and 12 kV class networks. Verify specific system voltage and pollution levels with our technical team before ordering.
Q2: How does the epoxy cast-resin design perform in coastal environments?
The epoxy resin housing provides excellent moisture resistance for standard outdoor use. For coastal or heavy-pollution areas, creepage distance and insulation coordination are customized by technical agreement.
Q3: What primary current ranges and accuracy classes are available?
It accommodates primary currents from 10 A to 2000 A with multiple accuracy combinations. Contact our engineers with your specific burden and ratio requirements for exact selection.
Q4: Are these current transformers compliant with standard GB specifications?
Yes, the LZZBJW-10/185/4S is fully compliant with GB 20840.1-2010 and GB 20840.2-2014 standards. Request the specific type test reports and compliance certificates for your project documentation.
Q5: Can the secondary current output be customized for specific protection relays?
Yes, it is available with standard 5 A or 1 A rated secondary currents. Specify your exact relay requirements during inquiry to ensure proper factory configuration.
Q6: Why is this epoxy cast-resin model preferred for outdoor medium-voltage systems?
It offers superior weather resistance and requires no maintenance compared to oil-filled alternatives. The design inherently withstands standard ambient temperatures from -25°C to +40°C without degradation.
Q7: When should we request special insulation coordination for this 12kV CT?
You must request special coordination for high-altitude, heavy-pollution, or coastal applications. Provide your exact installation environment details to our technical team to determine the required creepage distance.