0
Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
What is the purpose of impedance phlebography?
Impedance phlebography may be done in order to: detect blood clots lodged in the deep veins of the leg, screen patients who are likely to have blood clots in the leg, detect the source of blood clots in the lungs.
Which bulb is brighter a 60W or 30W in a series then in parallel then separate circuits?
In series, a 30W incandescent lamp dissipates twice as much power as a 60W unit
designed for the same supply voltage. While it's difficult to estimate how much of
that power will be in the form of visible light and how much as heat, we're guessing
that their comparative visual brightnesses will track the total power dissipation of
each lamp, so the 30W will appear brighter than the 60W.
In parallel, or in separate, independent, unconnected circuits on separate power supplies,
the 60W lamp is brighter than the 30W unit designed for the same supply voltage.
Note: Plugging two bulbs into any two separate outlets in the same house
normally connects them in parallel.
Why are Isolatorts not opened on Load?
To interrupt the current requires a more-expensive circuit-breaker. An isolator is used to isolate a section of power line after the current has been stopped.
What would happen if the length of wire increase what happens to the capacitance?
capacitance also increase
What are applications of space vector modulation?
Because there's sparking in DC motors, they are inherently less efficient than say AC motors are,
The trick with AC motors is that they run primarily at the frequency of their power source. What happens when the power source can change it's frequency and amplitude? The motor can behave
as well as any DC motor.
Does line to ground voltage always half the value of line to line voltage?
Line to Ground voltage = line to line voltage / 1.73
AnswerIt depends what configuration is being measured. In the case of the secondary of a split-phase distribution transformer used to supply residences in North America, the answer is yes. In the case of a star (wye) connected secondary distribution transformer used to supply residences in Europe, no: the line to ground voltage will be as described in the first answer.
What is the maximum capacity of 11kv transformer?
It depends on the design of the transformer but 1 MVA is a common size for an 11 kV / 415 v three-phase transformer.
The primary and secondary windings of a transformer are generally wound around tubular-shaped 'formers', and are fitted, concentrically -in other words, they are installed one around the other, and over the same limb of the transformer's laminated core, with the higher-voltage winding outermost. The primary and secondary windings are not fitted separately over different limbs, as represented in schematic diagrams of transformers.
In larger transformers, the two windings must have sufficient separation between them to allow for the circulation of oil. This oil has two purposes. The first is to provide insulation between the primary and secondary windings, over and above the insulation around the wound conductors. The second is to enable circulation for cooling -either by natural convection or by forced circulation.
The actual separation between the primary and secondary windings depends upon the voltage differences between the two windings. Greater voltage differences require greater separation. Typically we are talking in terms of tens of centimetres.
What are the disadvantages of the universal motors?
high maintainance and short life caused by commutator
produce more noice and vibration then induction motor
Why would four core armoured cable be used in a single phase circuit?
Four core armoured cable would be used in a circuit carrying 240 Volts 60 Hz AC that is installed in a location where it could get damaged, such as underground or under water. The 4 cores in the armoured cable would be used as the following conductors for the 240 V 60 Hz circuit: * "Red" hot (120V above Neutral)
* "Black" Hot (120V below Neutral)
* "Neutral"
* "Ground" to protect the circuit, connected to the main incoming supply panel which feeds the circuit.
What is the need of form factor in transformer?
transformer is a static device hence it needs form factor.
What are the parts of a dynamo?
Electric motor, the alternating-current alternator, and the rotary converter.
A basic dynamo consists of a stator wound with copper coils and a magnetic armature. As the magnetic armature spins it induces a current in the copper coils.
How does the high impedance fault occur in the system?
High impedance fault can occur on fail or low maintenance insulators (e.g. near coastal area) or wet vegetation area (in canyon), and highly loaded industrial area (high harmornics). It all depends on the ground moist level.
What is meant by resonating load?
A resonating load refers to a load in an electrical or mechanical system that exhibits resonance, typically occurring when the system's natural frequency matches the frequency of an external force or oscillation. This can lead to amplified oscillations and potentially excessive vibrations or currents, which can affect performance and stability. In electrical circuits, it can result in increased voltage and current levels, while in mechanical systems, it may cause structural damage or failure. Understanding resonating loads is crucial for designing systems that can mitigate these effects.
Four causes of faults on transmission lines?
Some cases I've seen:
-Nature:
-lightning strikes near line
-fires (I've seen farmers burn weeds out from under a line - the fire ionizes the air, and with the added particulates in the air create a path to ground)
-snow storms/icing on lines (can cause lines to sag)
-high winds (can cause lines to blow out, possibly making contact with trees, or can cause enough stress to break poles). Winds can also blow stuff into the lines
-tornados
-Animals:
-Two bears climbing a pole
-Two owls fighting near a line
-Eagle/other large birds swooping down between conductors
-Eagle/other large bird pooping on conductors
-People:
-farmers touching power lines with harvesting equipment
-crop dusters attempting to fly under lines
-people crashing cars into poles
What are the differences between series and shunt compensation?
you could compare the VI characteristics of both..talk about damping ability of both as well as their power transfer capability.
Can you use MCCB instead of fuse in a three phase connection?
Yes, three phase CDP (Central Distribution Panels) all use breakers to distribute the three phase supply voltage to their respective loads.
