Answer Wiki. For determining the PS, knee point voltage should be calculated before manufacturing the CT. For calculation of the knee point voltage, prerequisites are the transformer details such as kVA rating, impedance and distance of equipment from the CT. means ps class current transformer Definition of Instrument transformers means current transformer and voltage transformer are used in electrical power system for stepping down currents and voltages of the system for metering and protection purpose. Actually relays and meters used for protection and metering, are not designed for high currents and voltages.
Feb 14, 2008 What is PS class and 5P20 class protections in current transformer? What is the diffrence between the two? and therefore below magnetic saturation. at values up to perhaps 30 times full load current. This wide operating range means that protective current transformers require to be constructed with larger crosssections resulting means ps class current transformer
PS is a special class of protection transformer used in differential protection schemes. The CT is specified by what is known as the knee point (that is the point at which the CT saturates). Because they are specified using the knee point, two separate CTs will have the same characteristics. The above classes are used practically. CL The transformer class relates to it's accuracy. There are two different ways to represent this, depending if the current transformer is to be use for protection or metering. How can the answer be improved? means ps class current transformer The 5P10P or 5P20 class CTs cannot match the Characteristic as that of PS class. The core of PS class is such that very high current is needed for saturation of the core. Knee point voltage of the CT is of valid importance. The developed voltage across the relay terminals should be Knee Point Voltage of Current Transformer. So for choosing CT for differential protection of transformer, one should consider current transformer PS class rather its convectional protection class. PS stands for protection special which is defined by knee point voltage of current transformer V k and excitation current I e at V k2.