Janitza 250/5 - CTB 31.35 Plug-on Current Transformer, Primary 250 A, Secondary 5 A, Class 1, 5 VA 1503275

Accurate current measurement is critical for energy monitoring and protection in low-voltage distribution systems. The Janitza 250/5 - CTB 31.35 plug-on current transformer delivers reliable conversion of high primary currents up to 250 A into a standard 5 A secondary signal, enabling seamless integration with measuring instruments, energy meters, and protective relays. Its compact plug-on design simplifies installation on busbars or cables, reducing downtime and wiring errors.

Who is it for

This current transformer is ideal for electrical engineers, panel builders, and facility managers who need precise current sensing in industrial plants, commercial buildings, and infrastructure projects. It suits retrofit applications where space is limited and a non-invasive installation is preferred.

Main features

• Plug-on mounting on busbars up to 30 x 10 mm or cables up to 21 mm diameter
• High accuracy Class 1 for reliable measurement
• Rated burden 5 VA supports long secondary wiring runs
• Wide frequency range 50/60 Hz for global compatibility
• Overcurrent limit factor FS 5 ensures safe operation under fault conditions
• Compact and lightweight for easy handling
• IP20 protection suitable for indoor switchgear

Specifications

• Primary current: 250 A
• Secondary current: 5 A
• Transformation ratio: 250/5 A
• Accuracy class: Class 1
• Rated power: 5 VA
• Frequency: 50/60 Hz
• Overcurrent limit factor: FS 5
• Max. busbar dimensions: 30 x 10 mm
• Max. cable diameter: 21 mm
• Insulation voltage: 0.72 kV
• Operating temperature: -25 °C to +50 °C
• Protection class: IP20
• Connection: screw terminals

Tips

Ensure the primary conductor is centered through the transformer opening for best accuracy. Always short-circuit the secondary terminals before disconnecting the measuring instrument to avoid dangerous voltage spikes. For installations with high vibration, secure the transformer with cable ties.