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Understanding the differences between resistance and resistivity is very important as they are closely related. This article aims to bring you clarity on resistance and resistivity by comparing each of their properties, definitions and formula. Introduction Every object posses some amount of opposition to the flow of electric current. If the object is a conductor, … Read more
In order to supply loads exceeding the rating of an existing transformer, two or more transformers are connected in parallel to the existing one. The parallel operation of transformers facilitates load sharing between the transformers. When a connected load at a load centre exceeds the MVA of the existing transformer, it is easier and economical … Read more
Circuit breakers are devices that can protect circuits or loads during overloads and short circuit. The reliability of the circuit breakers during short circuits is determined by Ultimate breaking capacity (Icu) and Service breaking capacity (Ics) ratings. These ratings are mentioned in IEC/EN 60947-2. Definition of Ultimate breaking capacity (Icu) The term Ultimate breaking capacity … Read more
What is an instrument transformer? Instrument transformers are current and voltage transformation devices that are used to step down the transmission and distribution line voltages and currents to levels that can safely operate measuring instruments, protection devices and control relays by isolating it from the supply voltages. The above diagram shows the basic usage of … Read more
Current transformers (CT) and Potential Transformers (PT) are instrument transformer types used to step down transmission or distribution line voltages and current to the level that can be measured using measurement devices or controlled using control devices. The principle of operation of a certain type of CT and PT is similar to power transformers. Here … Read more
What is ‘locked rotor current’? A motor at rest acts as if its rotor is locked. The locked rotor current and the starting current of a motor are one and the same. It is the starting current drawn by a motor when full nominal voltage is applied to its terminals. Here is a simple locked … Read more
RCCB stands for Residual current circuit breakers and MCB stands for Miniature circuit breakers. Both of them are basic circuit protection devices found in the distribution boards of every house and commercial lighting power distribution boards. Here are the differences between MCB and RCCB. RCCB – Residual Current Circuit Breakers Residual current circuit breakers are … Read more
Potential transformers (PT) or voltage transformers are instrument transformers used for voltage measurements. They are connected in parallel to the line and operates under the same principle of power transformers. They cannot be used used to supply raw power to the loads. They have an accurate voltage ratio and phase relationship between primary and secondary … Read more
What is a current transformer? A current transformer is a type of instrument, used to measure or sense large alternating currents by scaling it to a smaller, safer and measurable value. It transforms the primary current to a proportional secondary value in terms of magnitude and phase. Current transformers are available in various sizes and … Read more
Some amount of power is lost during the voltage transformation process in a transformer. The current flows in a transformer winding and the alternating magnetic field in the core contributes to the majority of transformer losses.
