A circuit is defined as any electrical components, that permits the flow of electricity between two or more points. There are three main type of circuits commonly used within the electrical field and in different types of electrical technology. These circuits can be easily rectified and identified within the common circuit boards and any sections of building wiring.
A series circuit, is a circuit that contains one path for current to flow. A series circuit is commonly found an connected at the point of circuit breakers, fuses and resistors allowing current to flow through that part of the circuit only. The next type of circuit, is a parallel circuit. This type of circuit is most commonly used in residential, commercial and industrial buildings. Having this type of circuit, provide connections for lights, motors, and devices making all loads independent of each other.
The third circuit is called a combination circuit. The combination circuit, combines series and parallel circuit allowing several types of electrical connections. This type of circuit is commonly found in electric boards, and in motor control circuits, almost any where that requires the flexibility various types of wiring methods.
An electrical circuit overload develops when excessive amount of current is utilize and exceed the over-current device rating of the original branch circuit protection. If a circuit breaker or fuse interrupt the electricity under continuous usage, this could be a strong possibility of a circuit overload. The national electrical code states that the rating of the over-current device shall not be less the the noncontinuous load plus 125 percent of the continuous load.The branch circuit conductors shall not be less than 125 percent of the designed load.
A connection between any two or more conductors of an electrical system in such away as to significantly reduce the impedance of the circuit. The current flow is outside of its intended path. A short circuit is commonly referred to as electrical fault. When experiencing a short circuit, the over-current protection of the circuit immediately reacts for the protection of the circuit. The signs of a short circuit is a blown fuse, a tripped circuit breaker, wet wires, nicked or loose connections making a contact at some point.
A transformer is a magnetically operated machine that can change values of voltage, current, and impedance without a change of frequency. Transformers are the most efficient known. Their efficiencies commonly range from 90% to 99% at full load.
1. Isolation transformers: is a transformer used to transfer electrical power from a source of alternating current (AC) power to some equipment or device while isolating the powered device from the power source, usually for safety.
2. Auto transformers: is an electrical transformer with only one winding.
3. Current transformers: (CT) is a series connected measurement device designed to provide a current in its secondary coil proportional to the current flowing in its primary. Current transformers are commonly used in metering and protective relays in the electrical power industry.
All values of a transformer are proportional to its turns ratio. For example, assume a transformer has two windings. One wing, the primary has 1000 turns of wire, and the other, the secondary, has 250 turns of wire. The turn ratio of this transformer is 4 to 1.
Transformer power levels range from low-power applications, such as consumer electronics power supplies to very high power applications, such as power distribution systems. For higher power applications, three-phase transforms are commonly used.
The detailed analysis of this circuit is not straightforward since there are numerous combinations of flux paths linking various windings. For this reason, the three-phase transformer will be modeled as three independent single-phase transformers herein.