In this type of current transformer, the primary winding is nothing but a bar of suitable size. The construction is shown in the Fig. below:
The insulation on the bar types primary is bakelized paper tube or resin directly moulded on the bar. Such bar type primary is the integral part of the current transformer. The core and the secondary windings are same in bar type transformer.
The stampings used for the laminations in current transformers must have high cross-sectional area than the ordinary transformers. Due to this, the reluctance of the interleaved corners remains as low as possible. Hence the corresponding magnetizing current is also small.
The windings are placed very close to each other so as to reduce the leakage reactance. To avoid the corona effcet, in bar type transformer, the external diameter of the tube is kept large.
The windings are so designed that without damage, they can withstand short circuit forces which may caused due to short circuit in the circuit in which the current transformer is inseted.
For small line voltages, the tap and varnish are used for insulation. For line voltages above 7 kV the oil immersed or compound filled current transformers are used.
The insulation on the bar types primary is bakelized paper tube or resin directly moulded on the bar. Such bar type primary is the integral part of the current transformer. The core and the secondary windings are same in bar type transformer.
The stampings used for the laminations in current transformers must have high cross-sectional area than the ordinary transformers. Due to this, the reluctance of the interleaved corners remains as low as possible. Hence the corresponding magnetizing current is also small.
The windings are placed very close to each other so as to reduce the leakage reactance. To avoid the corona effcet, in bar type transformer, the external diameter of the tube is kept large.
The windings are so designed that without damage, they can withstand short circuit forces which may caused due to short circuit in the circuit in which the current transformer is inseted.
For small line voltages, the tap and varnish are used for insulation. For line voltages above 7 kV the oil immersed or compound filled current transformers are used.
