ABB RARIC Manuale d'uso - Pagina 5

Sfoglia online o scarica il pdf Manuale d'uso per Dispositivo di protezione ABB RARIC. ABB RARIC 17. Shaft current protection

17A

TRIP

16A

ALARM

2.2 The ILDD shaft current transformer

RARIC

Shaft current protection

Fig. 1

Basic circuit for RARIC.

The ILDD shaft-current transformer is of special design with high quality

core steel, where the number of secondary turns and the core cross-sec-

tional area are optimized to the diameter of the transformer to get the low-

est possible primary operate current when connected to the RXIK 1 relay.

The measuring and the test windings are covered with cotton tape and then

embedded in a circular shaped U-profile for mechanical protection and

magnetic screening. The profile with the core and the windings is then

embedded in resin.

The transformer is split up in two parts for sizes with inner diameter up to

and including 2 000 mm. For larger diameters, the transformer is split up

in four parts. When the parts are jointed, the steel sheets of the core are

interleaved with an overlap of about 30 mm.

The measuring winding, with 400 - 800 turns depending on the diameter

of the transformer, is evenly distributed on the parts of the core. When the

transformer parts are mounted together, the parts of the measuring wind-

ing must be connected to the terminals S, see Fig. 2. The pilot-wires to the

RARIC protection are connected to terminals S1 -S2, see Fig. 2.

The test winding has four turns and is connected to terminals marked

A and B.

+ +

1MRK 502 001-UEN

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