2.13 Current Transformer

The current transformer input is fitted in all controllers.

 

 

• C terminal is common to both the CT input and Digital input 1. They are, therefore, not isolated from each other, the sensor input or the logic outputs.

 

• CT input current: 0-50mA rms (sine wave, calibrated) 50/60Hz.

 

• A burden resistor, value 10Ω, is fitted inside the controller.

 

• It is recommended that the current transformer is fitted with a voltage limiting device to prevent high voltage transients if the controller is unplugged. For example, two back to back zener diodes. The zener voltage should be between 3 and 10V, rated at 50mA.

 

• CT input resolution: 0.1A for scale up to 10A, 1A for scale 11 to 100A.

 

• CT input accuracy: +4% of reading.