Power distribution equipment
About JOHNN
Located in Yueqing Economic Development Zone, Zhejiang Province, JOHNN operates a modern manufacturing facility covering more than 18,000 square meters. We specialize in the research, development and manufacturing of power transformers, instrument transformers, and low- and medium-voltage electrical enclosures and switchgear solutions.
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18,000+
M²
Modern manufacturing facility
50M+
USD
Annual production value · 2025
IEC & GB
Standards commitment
ISO
9001 · 45001 · SA 8000
CE & UKCA
Product conformity certificates
Services
OEM & ODM CustomizationBranding, models, packaging, labels and technical documents tailored to project requirements.
Sample DeliverySamples and small trial orders are available for technical confirmation before volume production.
Quality Control & TestingInspection covers dielectric withstand voltage, partial discharge, temperature rise, electrical performance and mechanical reliability.
Reliable Delivery & LogisticsSupport for stable lead times, export packing, shipment coordination and customs documentation.
Pre-sales Technical SupportTechnical guidance for product selection, configuration and quotations.
After-sales Warranty ServiceResponsive support for installation, operation and maintenance.
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Industries We Serve
Power DistributionPower transformers, instrument transformers and electrical enclosures for distribution networks.
Renewable EnergyPower distribution equipment for renewable-energy projects and related electrical systems.
Industrial FacilitiesElectrical equipment solutions for industrial facilities and their distribution requirements.
Infrastructure ConstructionPower distribution equipment for infrastructure construction and supporting electrical works.
Utility Grid ModernizationTransformer and enclosure solutions for utility-grid modernization projects.
Certificate Display
Latest Articles
All articles
Instrument Transformer vs Power Transformer: Signals or Energy
Learn the difference between instrument transformer and power transformer by duty, burden, and accuracy—then open a live indoor CT metering path.
How to Test a Voltage Transformer Before You Trust Its Secondary
Learn how to test a voltage transformer: nameplate checks, insulation resistance, polarity, primary-side ratio, burden awareness, and an indoor VT next step.
Current Transformer Wiring Checks Before You Leave It in Service
Learn current transformer wiring: P1/P2 and S1/S2 orientation, never-open secondary shorting, sensor vs CT secondary contrast, and an indoor CT next step.