CT ankle point & knee point voltage: Material Selection for CT | CT Characteristics: CT Saturation

Описание: In this video I have described CT Saturation, causes of Current Transformer saturation, Definition of CT saturation, ankle point voltage, Knee point voltage and Material Selection for CT core.
CT Saturation:
Whenever Magnetic dipole of CT core align with the field dipole of Alternating Current then CT becomes saturated which means that no flux change anymore, this leads to zero induced emf at secondary and consequently secondary current also becomes zero. Now all the primary current will be spend on magnetizing the core and hence CT will be saturated if this phenomena sustain for some time.

Causes of CT Saturation:
there are many reasons of CT saturation, few reasons are here below
1. If secondary of CT is open circuited then CT will saturate.
2. In case of high magnetic flux density will align the magnetic dipole of core with the field dipole of AC current and will saturate the CT.

Types of CT Saturation:
there are two types of CT saturation
1. Symmetrical Saturation
in this type of CT saturation area under the curve above or below the zero crossing will be same and have no DC component.
2. Asymmetrical Saturation
In this type of CT saturation there will be a DC component and because of that DC component area under the curve above or below the zero crossing will not be same.

Ankle point:
Ankle point is the point where measurement CT saturates and hence no more secondary current.

Knee point voltage:
At knee point Protection CT Saturation starts and every 10% of primary current will add 50% of excitation current. Protection CT operating region is between the ankle point and knee point voltage.

Material Selection for CT core:
for measurement CT Nikle iron alloy is the best material because of high permeablilty while for protection CT grain oriented silicon steel is the best material because of low permeability.