315052394

TECHNICAL UNIVERSITY of LODŹ

MF CT Current Transformer of Medium Frequency

Ryszard NOWICZ'¹    Regina RAJCHERT*²

The conventional current transformer MF CT can be used in high-current circuits of an elevated frequency e.g. in power electronic systems or in electrothermics. A special construction of the transformer makes decrease in the magnetic flux density in the core with an increase in frequency (Fig. 1) which causes a considerable reduction of losses in the ferromagnetic materiał and a slight increase in the temperaturę. Also, if the magnetic flux density is constant, there is possible to increase the load of secondary Circuit (Fig. 2).

RATINGS

S1

S2

Conventional current transformers of mean frequency used in power networks are usually manufactured up to 10 kHz. The MF CT that is presented, achieves much morę output power in comparison to electronic transducers and is not liable to be destroyed. in transient State. The MF CT is competitive to conventional electronic transducers from technical and economical point of view.

Patent Office Bulletin Numer 1(731)2002

Primary currents:    from 5A to 100A

Secondary currents: from 20mA to 5A Freguency:

Accuracy:

Burden:

50Hz-20kHz 10kHz-100kHz 20kHz-500kHz 1% or 3% 5VA or 10VA

carbonized

housing

Conventional current transformer that has been failed in 30 kHz power network.

2) Polcontact - Warsaw tel/fax: [phone]

1

Departments of Applied Electrical Engineering & Instrument Transformers TECHNICAL UNIVERSITY of LODŹ

2

90-924 ŁÓDŹ, POLANO, ul. Stefanowskiego 18/22, tel/fax: [phone], [e-mail].p!