Difference among Rogowski coils, LVCTs and conventional CTs

Product Line

Rogowski coils, LVCT, 3090SCCT and Instrument CTs.

Environment

Current Transformer, CT.

Resolution

Rogowski coils

The Rogowski coils are rope-style current transducers and they provide secondary AC voltage proportional to the primary (sensed) current. The flexible core makes it easy to fit in tight enclosures. Leads are connected directly to the X1 and X2 inputs in the meter.

Accuracy ±1% from 50 to 5000 A

Environment

EM35xxA, EM42xx, iEM3555 and iEM3565

LVCT

These are current transducers with proportional Voltage output on the secondary side. There are 2 output options for this CT either 1 V or 0.333v at 100% of the rated current. The transducer output leads are connected to the meter inputs where the white wire is the X1 lead. The user needs to specify the CT primary in the meter settings.

Accuracy 1% from 10% to 100% of rated current

Environment

EM35xx, EM42xxEM4033, EM4833, EM49xx, iEM3455, iEM3465 and BCPM (mains)

HDPM6000

This meter uses special LVCTs, they can be found in this installation guide.

These CTs range from 20A to 4000A voltage ratings with 0.2% to 1% accuracy.

Output at Rated Current 0.25VAC

Instrument transformers

The conventional CT has a current output proportional to the Primary side. The most common CT secondary values are 1A and 5A outputs. There are other CT options, the CT secondary can be as low as 80mA or as high as 10A or even 20A (make sure the meter is compatible with this current input value). A shorting block is necessary for the installation. For all these CTs, the CT ratio needs to be entered into the meter so the device can calculate the actual current on the CT primary.

Accuracy

3090SCCT, ±1% of reading from 5% to 100% of rated current. See installation guide.

For other models, see accuracy class. Instrument Transformer

Environment

iEM32xx, PM5000 series, PM2000 series, PM8000, ION7400, ION9000, ION8650, EM4880, EM4805, EM4080, EM4005

Released for:Schneider Electric South Africa