What is X R ratio of a transformer?
What is X R ratio of a transformer?
The X/R ratio of a transformer is simply the imaginary part of its impedance divided by the real part of its impedance. When used in conjunction with the X/R ratio above the transformer’s primary, it’s used to calculate the maximum, asymmetric, secondary fault current capability.
What is motor x R ratio?
2) Calculate the X/R ratio of the motor. If the motor kV is greater than 1.0 and the MW per pole-pair is greater than or equal to 1.0, then X/R is 10.0. If the motor kV is greater than 1.0 and the MW per pole-pair is less than 1.0, then X/R is 6.667.
Why X R ratio is high in transmission line?
In Transmission Lines the Deq which is the Geometric Mean distance among conductors is very larger than overhead distribution lines. So the X/R ratio in transmission lines is larger than distribution lines.
What is X in a transformer?
On transformers, the H represents the higher voltage or primary side of the transformer, whereas the X is the lower voltage or secondary side of the transformer.
What is X R rating?
The X/R ratio affects the dc component, and therefore, also the total current. The higher the X/R ratio of a circuit, the longer the dc component will take to decay (longer time constant). To illustrate, two circuits are shown in Figure 1.
What is Z in transformer?
The percentage impedance of a transformer (Z%) is the voltage drop on full load due to the winding resistance and leakage reactance expressed as a percentage of the rated voltage. The ratio of voltage applied to circulate full load current to the primary voltage is the percentage impedance of the transformer.
How do you calculate motor impedance?
Formula Cheatsheet
- Impedance Z = R or XLor XC(if only one is present)
- Impedance in series only Z = √(R2 + X2) (if both R and one type of X are present)
- Impedance in series only Z = √(R2 + (|XL – XC|)2) (if R, XL, and XC are all present)
- Impedance in any circuit = R + jX (j is the imaginary number √(-1))
What is typical XR ratio of transmission line?
According to IEEE Std. 242, a 1500 kVA transformer with a secondary voltage < 600 Volts and a primary voltage of up to 15,000 Volts, the suggested X/R ratio is 7.0.
What is X R ratio of transmission line?
The ratio of X to R is greater than one for the transmission line and distribution line. In underground distribution networks (cables) the X/R ratio is very small and maybe smaller than 1.
How do you calculate voltage impedance?
Effective Percent Impedance
- Transformer reactance Xt = (kV2/MVA) x %Z/100 = (0.482 / 0.5) x 0.06 = 0.027648 ohms.
- Rated secondary current = 500,000 / (480 x 1.732) = 601.4 amps.
- Actual Load current = 300 amps.
- Voltage drop at actual load = 300 x 1.732 x 0.027648 = 14.36 volts (14.36 / 480 = 0.0299, or 3% of 480 volts)
What is X R ratio used for?
Why is the X/R ratio important? Its importance is that it affects the level of short circuit current a circuit breaker is required to interrupt. When a short circuit occurs, the rms value of the symmetrical fault current is determined by the system source voltage and the total system impedance to the point of fault.
What is the impedance voltage?
The % impedance is formally referred to as impedance voltage. It is the supply voltage, expressed as a % of rated voltage, that is required to circulate rated current through the transformer. The supply voltage magnitude that results in rated current is then referred to as the impedance voltage.
What is the current transformer ratio?
Most current transformers have a the standard secondary rating of 5 amps with the primary and secondary currents being expressed as a ratio such as 100/5. This means that the primary current is 20 times greater than the secondary current so when 100 amps is flowing in the primary conductor it will result in 5 amps flowing in the secondary winding.
What is the simplest form of ratio?
The simplest form is 4:9. The process to complete ratio simplification questions such as this is to divide each side by the highest common factor. That is the highest number which divides evenly into both numbers.
How do you identify equivalent ratios?
You can find equivalent ratios by multiplying or dividing both sides by the same number.
What is an example of a current ratio?
Examples of current liabilities include accounts payable, salaries and wages payable, current tax payable, sales tax payable, accrued expenses, etc.
