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3 years ago

A 1000 KVA three phase transformer has a secondary voltage of 208/120. What is the secondary full load amperage?

Engineering

1 answer:

IceJOKER [234]3 years ago

4 0

Answer:

The three phase full load secondary amperage is 2775.7 A

Explanation:

Following data is given,

S = Apparent Power = 1000 kVA

No. of phases = 3

Secondary Voltage: 208 V/120 V (Here 208 V is three phase voltage and 120 V is single phase voltage)

Since,

$V_{1ph} =\frac{ V_{3ph}}{\sqrt{3} }\\V_{1ph) = \frac{208}{\sqrt{3} }\\$

$V_{1ph} = 120 V$

The formula for apparent power in three phase system is given as:

$S = \sqrt{3} VI$

Where:

S = Apparent Power

V = Line Voltage

I = Line Current

In order to calculate the Current on Secondary Side, substituting values in above formula,

$1000 kVA = \sqrt{3} * (208) * (I)\\1000 * 1000 = \sqrt{3} * (208) * (I)\\I = \frac{1000 * 1000}{\sqrt{3} * (208) }\\ I = 2775.7 A$

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Yield and tensile strengths and modulus of elasticity . with increasing temperature. (increase/decrease/independent)

meriva

Answer:

Yield strength, tensile strength decreases with increasing temperature and modulus of elasticity decreases with increasing in temperature.

Explanation:

The modulus of elasticity of a material is theoretically a function of the shape of curve plotted between the potential energy stored in the material as it is loaded versus the inter atomic distance in the material. The temperature distrots the molecular structure of the metal and hence it has an effect on the modulus of elasticity of a material.

Mathematically we can write,

$E(t)=E_o[1-a\frac{T}{T_m}]$

where,

E(t) is the modulus of elasticity at any temperature 'T'

$E_o$ is the modulus of elasticity at absolute zero.

$T_{m}$ is the mean melting point of the material

Hence we can see that with increasing temperature modulus of elasticity decreases.

In the case of yield strength and the tensile strength as we know that heating causes softening of a material thus we can physically conclude that in general the strength of the material decreases at elevated temperatures.

6 0

3 years ago

What does the current in a semi-conductor is produced by?

lesya [120]

Current flow in a semiconductor arises from the motion of charge carriers in both the conduction and valence bands. As explained in chapter 4, the mobile charges in the conduction band are electrons and those in the valence band are holes.

Here u goo!!

5 0

3 years ago

Read 2 more answers

The two boxcars A and B have a weight of 20000lb and 30000lb respectively. If they coast freely down the incline when the brakes

kolbaska11 [484]

Answer:

T=5.98 kips

Explanation:

First, introduce forces, acting on both cars:

on car A there are 4 forces acting: gravity force mA*g, normal reaction force, friction force and force T- it represents the interaction between cars A and B. On car B, there are three forces acting: gravity force, normal reaction force and force T. Note, that force T is acting on both cars, but it has opposite direction. Force T, acting on car A has direction, opposite to the friction force, whether the T, acting on B, is directed backwards- in the same direction with the friction force. Note, that both cars have the same acceleration, which is directed backwards.

Once the forces were established, we can write components of the Second Newtons Law on vertical and horizontal axes, considering that horizontal axis is directed backwards- in the same direction with the acceleration:

For car A on the vertical axis the equation is: -mAg+NA=0

For car A on the horizontal axis, the equation is: Ffr-T=mAa

For car B, on the vertical axis the equation is: -mBg+NB=0

For car B, on the horizontal axis, the equation is: T=mBa

We need to solve these equations to find force T, knowing that Ffr=μmAg, where

After the transformations, the equations for acceleration and force in the coupling will be:

a=(μmAg)/(mA+mB)=6.43 ft/s2- note, that the given answer is not correct for the given numerical values;

and force T: T=μmAmBg/(mA+mB)=6.0 kips- note, that the force answer is in line with the given numerical value

5 0

4 years ago

A 200 W vacuum cleaner is powered by an electric motor whose efficiency is 70%. (Note that the electric motor delivers 200 W of

Goshia [24]

Answer:

The rate at which this vacuum cleaner supply energy to the room when running is 285.71 Watts.

Explanation:

power efficiency of electric motor = 70% = 0.70

The power output of the vacuum cleaner = $P_o$ = 200 W

The power output of the vacuum cleaner = $P_i$

$Efficiency=\frac{P_o}{P_i}$

$0.70=\frac{200 W}{P_i}$

$P_i=\frac{200 W}{0.70}=285.71 W$

The rate at which this vacuum cleaner supply energy to the room when running is 285.71 Watts.

5 0

3 years ago

If 200 amperes flow from the positive terminal of a battery and operate the starter motor, how many amperes will flow back to th

garri49 [273]

Answer:

$200$ Amperes WB = $200J$

Explanation:

$200$ Amperes will flow back to the negative terminal because both the positive terminal and negative terminal contain the equivalent amount of current that will flow and it works in the starter motor.

To learn more about it, refer

to brainly.com/question/6561461

#SPJ4

5 0

2 years ago