Fuyi Switch LZZBJ9-10 Current Transformer Passed IEC 61869 Type Tests

We are pleased to announce that our LZZBJ9-10 cast-resin current transformer has successfully passed all type tests conducted by Guoxinbiao Testing and Certification (Huizhou) Co., Ltd., in full compliance with IEC 61869-1:2007 and IEC 61869-2:2012.

Product Overview

The LZZBJ9-10 is an indoor, epoxy-resin cast, support-type current transformer designed for 10kV-class AC power systems. The "LZZBJ9" designation breaks down as follows:

This series is widely used in medium-voltage switchgear for both revenue metering and system protection applications.

Test Report Summary

The type test was conducted between 30 June 2026 and 30 July 2026, under ambient conditions of 20°C–25°C and 45%–70% relative humidity. The sample was tested against the IEC 61869 series, the international benchmark for instrument transformer performance and safety.
All test items passed with the following key results:

Key Performance Highlights

1. Accuracy Class: 0.2S (Metering) & 10P10 (Protection)
The LZZBJ9-10 features dual-core configuration:
Metering core (0.2S class): Designed for revenue-grade accuracy with minimal ratio and phase errors.
Protection core (10P10 class): Ensures reliable relay operation under fault conditions.

2. High Insulation Reliability
Lightning impulse withstand voltage: 75kV peak – successfully withstood 15 successive impulses at both polarities without disruptive discharge.
Power-frequency withstand voltage: Passed 42kV primary winding test and 3kV secondary winding test.
Partial discharge level: ≤ 50 pC at 14.4kV, far below the allowable limit – a critical indicator of insulation quality and long-term service life.

3. Excellent Thermal Performance
Temperature rise test results showed winding temperature rise ≤ 36K, well within the 60K limit specified by IEC 61869-1. This ensures stable operation under continuous rated load conditions.

4. Robust Short-Circuit Withstand Capability
Short-time thermal current: 45kA (r.m.s.) for 1 second
Dynamic stability current: 112.5kA (peak)
These values confirm the transformer's ability to withstand severe fault currents without mechanical or thermal damage – a key requirement for protection-grade CTs.

5. Inter-turn Overvoltage Protection
The inter-turn insulation test confirmed the winding can withstand open-circuit secondary conditions without damage – an essential safety feature for current transformers in field service.

Model Variants & Configuration Options

The LZZBJ9-10 series is available in three mechanical variants (A, B, C) to accommodate different switchgear layouts and mounting constraints:

Typical Technical Specifications:

Why This Matters for Your Project

For engineers, procurement specialists, and project managers working on medium-voltage substations, switchgear, and distribution systems, this type test report provides independent verification that the LZZBJ9-10 current transformer:
Meets international IEC standards – critical for projects requiring compliance with global specifications.
Delivers accurate revenue metering – the 0.2S accuracy class ensures minimal billing errors.

Ensures reliable protection – the 10P10 class and high short-circuit withstand capability guarantee relay performance under fault conditions.
Has proven insulation integrity – partial discharge below 20 pC indicates long service life and low failure risk.
Is suitable for harsh environments – flame-retardant, high dielectric strength, and robust mechanical construction.

Test Report Availability

The complete test report (Report Number: UCT1630J156) is available upon request. It includes:
Detailed test procedures and measurement data
Accuracy test tables for all current ratios
Lightning impulse oscillograms
Short-time current test waveforms
To request the full report or inquire about specific configurations, please contact our technical sales team.

About Fuyi Switch

Yueqing Fuyi Switch Co., Ltd. has been manufacturing high-voltage switchgear components for over 25 years. Our product range includes:
Epoxy resin insulators (post insulators, wall bushings, contact boxes)
Current and voltage transformers (cast-resin type)
Surge arresters (metal oxide type)
Switchgear parts and accessories

All products are manufactured under strict quality control and are available with OEM/ODM customization.