Overview
The LZZBJ9-24/180b/2S is an indoor, single-phase, epoxy resin cast current transformer designed for 20kV, 22kV and 24kV medium-voltage switchgear systems. It features a fully enclosed cast-resin body that provides excellent mechanical strength, moisture resistance, and stable dielectric performance under normal indoor operating conditions.
This dual-secondary CT supports standard accuracy classes including 0.2, 0.5, 10P10, 10P15, 5P10, and 5P20, making it suitable for applications requiring both metering and relay protection functions. It is commonly used in utility distribution substations, industrial MV panels, and compact feeder bays where space-efficient integration of measurement, protection, and optional live-status indication is required. The design complies with IEC standards for 24kV-class equipment.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage Class | 20kV / 22kV / 24kV |
| Rated Insulation Level | 24/65/125kV |
| Rated Frequency | 50Hz or 60Hz |
| Primary Current | As per standard ratios (e.g., 100–3000A) |
| Secondary Current | 5A or 1A |
| Secondary Configuration | 2S (two independent windings) |
| Accuracy Classes | 0.2, 0.5, 10P10, 10P15, 5P10, 5P20 |
| Insulation Medium | Epoxy resin (dry-type) |
| Phase | Single-phase |
| Installation Type | Busbar-type, indoor switchgear |
| Operation Condition | Indoor |
| Charged Display Option | Available if ≤3 secondary cores |
Model Designation
- L: Current transformer
- Z: Indoor type / post-type structure reference
- ZB: Epoxy cast-resin current transformer series
- J: Reinforced or structural design reference
- 9: Design sequence / product platform
- 24: 24kV equipment maximum voltage class
- 180b: Width and structure code for this compact platform
- 2S: Two secondary winding groups
Construction
The LZZBJ9-24/180b/2S features a robust, fully enclosed epoxy resin cast body that ensures high mechanical stability and reliable insulation performance in indoor environments. The primary circuit is implemented as a top-mounted busbar-type terminal (P1/P2), allowing direct integration into switchgear busbar systems without additional connectors. The secondary windings are housed in a lower terminal box, providing easy access for wiring to meters, relays, or monitoring devices.
Internally, the core and windings are vacuum-cast in cycloaliphatic epoxy resin, which offers superior tracking resistance, thermal endurance, and protection against humidity and contamination. This dry-type, maintenance-free construction eliminates the need for oil or gas insulation, enhancing safety and simplifying installation in confined indoor panels.
Technical Parameters
Service Conditions
- Installation: indoor
- Rated voltage: 20kV, 22kV and 24kV class systems
- Rated frequency: 50Hz or 60Hz
- Ambient temperature: -5°C to +40°C
- Installation environment: should be free from severe vibration, conductive dust, corrosive gas, explosive media and abnormal condensation.
Technical Parameters
The LZZBJ9-24/180b/2S is a cast-resin insulated indoor current transformer rated for 20kV, 22kV, and 24kV class systems. It operates within an ambient temperature range of -5°C to +40°C and complies with GB/T 20840.2-2014 and IEC 61869-2:2012 standards. The device supports primary currents from 20A to 1250A (extendable by agreement) with dual-secondary windings for combined metering and protection applications.
| Type | Rated Primary Current (A) |
Accuracy Classes Combination |
Rated Output (VA) |
Short-Time Thermal Current (kA/1s) |
Rated Dynamic Current (kA) |
|---|---|---|---|---|---|
| LZZB9-24/180b/2S | 20, 30, 40, 50, 75, 100, 150 |
0.2/0.2 0.2/0.5 0.2/10P10 0.5/10P10 0.2/10P15 0.5/10P15 |
10/10 10/10 10/15 10/15 10/10 10/10 |
150 I1n | 375 I1n |
| 200 | 31.5 | 80 | |||
| 300, 400, 500 | 45 | 112.5 | |||
| 600, 800 | 0.2/0.2 0.2/0.5 0.2/10P10 0.5/10P10 0.2/10P15 0.5/10P15 |
15/15 15/20 10/20 15/20 10/15 15/15 |
63 | 130 | |
| 1000, 1500, 1250 | 80 | 160 | |||
| 1000, 1500, 1250 | 80 | 160 |
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
Windings & Terminal Marking
The LZZBJ9-24/180b/2S current transformer is designed for indoor installation within 24kV switchgear. It is mounted using the base mounting holes (approx. 300mm length) onto a structural support inside the panel. The busbar-type primary terminals (P1/P2) at the top must align precisely with the switchgear’s main busbar layout. Adequate clearance must be maintained around the secondary terminal box, grounding point, charged display wiring area, and terminal cover opening during panel design to ensure safe access and operation.
Selection & FAQs
Selection Guide
- Select the LZZBJ9-24/180b/2S for compact 24kV indoor applications requiring two secondary winding groups.
- Confirm compatibility with charged display devices if visual indication of live busbars is needed (requires ≤3 secondary cores).
- Verify voltage class—this model supports 20kV, 22kV, and 24kV systems with a rated insulation level of 24/65/125kV.
- Ensure physical dimensions align with switchgear design, including busbar terminal spacing, body width, and mounting hole layout.
- Specify secondary output (1A or 5A), accuracy class combination for metering and protection, and rated burden during ordering.
Frequently Asked Questions
Q1: Can this 24kV current transformer be used on 20kV systems?
Yes, it is rated for 20kV, 22kV, and 24kV class systems. It operates at 50Hz or 60Hz indoors. Confirm your exact system voltage during ordering.
Q2: Which accuracy class combination is best for combined metering and protection?
The 0.2/10P10 combination is ideal for dual-secondary applications. One winding handles metering while the other manages protection. Specify your exact VA requirements to the factory.
Q3: What is the short-time thermal current rating for a 200A primary?
For a 200A primary, the short-time thermal current is 31.5 kA for 1 second. The rated dynamic current is correspondingly higher. Request the full dynamic current table for other ratings.
Q4: Are there specific environmental restrictions for installing this epoxy resin CT?
Yes, strict environmental restrictions apply. Installation must be indoors between -5°C and +40°C, free from conductive dust and corrosive gases. Verify site conditions before installation.
Q5: Which international standards does this indoor current transformer comply with?
It complies with IEC 61869-2:2012 and GB/T 20840.2-2014 standards. Standard test reports are provided upon request. Contact us for specific third-party certification requirements.
Q6: Can the primary current rating be customized beyond 1250A?
Standard ratings range from 20A to 1250A. Primary currents beyond 1250A are extendable by special agreement. Submit your exact project specifications for factory evaluation.
Q7: What type of manufacturer produces this cast-resin current transformer?
We manufacture specialized indoor epoxy resin cast current transformers. This model is designed for 24kV class medium-voltage switchgear applications. Reach out for factory audit details and product catalogs.