Instrument Transformers

Introduction of Instrument Transformers Instrument Transformers are used in AC system for measurement of electrical quantities i.e. voltage, current, power, energy, power factor, frequency. Instrument transformers are also used with protective relays for protection of power system. Basic function of Instrument transformers is to step down the AC System voltage and current. The voltage and … Read more

Current Transformer CT class Ratio Error Phase Angle Error in Current Transformer

Definition of Instrument Transformer 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. High currents or voltages of electrical … Read more

Voltage Transformer or Potential Transformer Theory

Potential Transformer Definition Potential transformer or voltage transformer gets used in electrical power system for stepping down the system voltage to a safe value which can be fed to low ratings meters and relays. Commercially available relays and meters used for protection and metering, are designed for low voltage. This is a simplest form of … Read more

Accuracy Limit Factor and Instrument Security Factor of Current Transformer

Before understanding accuracy limit factor and instrument security factor of CT or current transformer we must try to understand different technical parameters of instrument transformer i.e. of current transformer and voltage transformer. Technical Parameters of Instrument Transformer Following are some of the normally used terms associated with instrument transformer, that is, both for current transformer … Read more

Knee Point Voltage of Current Transformer PS Class

Current Transformer PS Class Before understanding Knee Point Voltage of Current Transformer and current transformer PS class we should recall the terms instrument security factor of CT and accuracy limit factor. Instrument Security Factor or ISF of Current Transformer Instrument security factor is the ratio of instrument limit primary current to the rated primary current. … Read more