Overview
The LZZB11-24/180-220 is an indoor single-phase epoxy cast-resin voltage transformer designed for 20kV, 22kV, and 24kV medium-voltage switchgear systems. It features a fully enclosed dry-type construction with epoxy resin insulation, providing stable dielectric performance and moisture resistance in indoor environments.
This voltage transformer delivers accurate secondary voltage signals for metering reference and protection relay applications at 50Hz or 60Hz. It complies with GB 20840.3-2013 and IEC 61869-3:2011 standards, making it suitable for utility substations, industrial distribution rooms, and compact MV switchgear requiring reliable voltage sensing and clear terminal identification.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage Class | 20kV / 22kV / 24kV |
| Rated Insulation Level | 24/65/125kV |
| Frequency | 50Hz / 60Hz |
| Phase | Single-phase |
| Insulation Medium | Epoxy cast-resin |
| Application | Voltage measurement, metering, protection |
| Installation Environment | Indoor |
| Standards | GB 20840.3-2013, IEC 61869-3:2011 |
Model Designation
- L: Current transformer (legacy designation retained in model series)
- Z: Epoxy cast-resin insulation
- Z: Indoor type
- B: With protective winding (historical context; this unit is a VT)
- 11: Design sequence number
- 24: Rated voltage class (24kV system)
- 180-220: Structural code indicating installation layout options (standard and 2×600A variants)
Construction
The LZZB11-24/180-220 employs a monolithic epoxy cast-resin structure, integrating primary and secondary windings into a solid, void-free insulation body. This dry-type construction eliminates oil or gas, ensuring maintenance-free operation and enhanced fire safety in indoor switchgear. The cast-resin material provides excellent tracking resistance, mechanical strength, and long-term stability under thermal cycling. Primary terminals are embedded in the resin with defined creepage distances, while secondary terminals feature clear P1/P2 and S markings for polarity-sensitive connections. The housing includes mounting flanges compatible with standard indoor panel configurations, supporting both standard and 2×600A layout references as shown in the installation diagram.
Technical Parameters
Service Conditions
- Installation site: indoor medium-voltage switchgear
- Rated frequency: 50Hz / 60Hz
- Ambient temperature: -5°C to +40°C
- Installation environment: should be free from severe pollution, conductive dust, corrosive gas, explosive medium and heavy condensation.
- Altitude, humidity, seismic requirement and special environmental conditions: should be confirmed according to project specification.
Technical Parameters
The LZZB11-24/180-220 is an indoor epoxy cast-resin voltage transformer designed for 20kV, 22kV, and 24kV systems. It features a fully enclosed epoxy resin cast body, operates within an ambient temperature range of -5°C to +40°C, and complies with GB 20840.3-2013 and IEC 61869-3:2011 standards. Altitude and other environmental parameters are subject to project-specific confirmation.
| Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Rated Short-Time Thermal Current (kA/1s) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|
| 20–40 | 0.2S 0.5 |
10 15 |
80 I1n | 2.5 Ith |
| 50–100 | ||||
| 150–250 | ||||
| 300–600 | ||||
|
10–20 15–30 20–40 30–60 40–80 100–200 150–300 200–400 300–600 |
0.2S 0.5 |
10 15 |
80 I1n | 2.5 Ith |
|
100–150–200–300 150–200–300–400 200–300–400–600 |
0.2S 0.5 |
10 15 |
80 I1n | 2.5 Ith |
Note:
1. Rated output and its relative accuracy class only one alternative.
2. 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 LZZB11-24/180-220 voltage transformer is installed using a four-hole base mounting structure. Final hole positions must be confirmed against the approved drawing. Ensure adequate clearance for top terminal spacing (220mm reference), maintenance access, and alignment with switchgear busbars. For 2×600A configurations, verify the primary terminal layout separately as it differs from the standard arrangement.
Wiring Diagram
Secondary wiring must follow the project-specific wiring diagram and local electrical safety regulations. Terminal markings correspond to the designated transformation ratio, accuracy class, and burden specified for the application. Confirm the correct terminal arrangement for either standard or tapped configurations before connection. The secondary side must never be short-circuited during normal operation.
Selection & FAQs
Selection Guide
- Select based on system voltage: suitable for 20kV, 22kV, and 24kV indoor switchgear applications.
- Verify compliance with IEC 61869-3:2011 and GB 20840.3-2013 standards for voltage transformers.
- Choose the correct wiring configuration (standard P1/P2-S1/S2 or multi-output C1/C2-S1/S2/S3) matching your project diagram and nameplate.
- Confirm mechanical compatibility including structure code, terminal spacing, base mounting holes, and cabinet maintenance access.
- Specify required electrical parameters: transformation ratio, rated burden, accuracy class, and grounding point location.
- Indicate layout preference—standard or 2×600A—and provide certificate or test report requirements during ordering.
Frequently Asked Questions
Q1: Which medium-voltage systems is this transformer designed for?
It is designed for 20kV, 22kV, and 24kV indoor switchgear. The unit features a fully enclosed epoxy cast-resin body. Confirm specific system voltage requirements with our engineering team.
Q2: Can this epoxy resin voltage transformer be installed outdoors?
No, it is strictly designed for indoor installation. The service environment must be free from severe pollution, conductive dust, and corrosive gases. Contact us for outdoor alternative models.
Q3: What international standards does this indoor voltage transformer comply with?
It fully complies with IEC 61869-3:2011 and GB 20840.3-2013 standards. The transformer offers 0.2S and 0.5 accuracy class combinations. Request the specific accuracy class for your application.
Q4: How are factory tests handled before shipment?
Routine tests are conducted according to IEC 61869-3 and GB 20840.3 standards. Specific type tests and special environmental validations are subject to project confirmation. Contact our sales team for detailed test reports.
Q5: When should high altitude conditions be confirmed?
Site conditions must be confirmed during the initial inquiry phase. Altitude, humidity, and seismic requirements are subject to project confirmation. Provide exact specifications early to avoid delivery delays.
Q6: Where is this 24kV voltage transformer typically applied?
It is primarily applied in indoor medium-voltage switchgear for 20kV to 24kV power distribution networks. The epoxy cast-resin design ensures reliable voltage measurement. Contact us for application-specific technical support.