What is over fluxing in transformer?
In transformer over fluxing is the dangerous situation in which magnetic flux density increases to extremely high level. The high flux density increases core loss which may lead to overheating of components which in turn may result into internal fault.
How do you calculate voltage per hertz?
The Volt/Hz ratio is calculated by taking the rated voltage of the drive (such as 460 Volts) and dividing by the line frequency (typically 60 Hz or 50 Hz). For example, a 460 Volt drive running on 60 Hz has a ratio of: 460 V / 60 Hz = 7.67 V/Hz.
What is the relation between voltage and frequency in a transformer?
The voltage of a transformer has a proportional relationship with frequency. Voltage of a transformer at a given flux density increases with frequency and also decreases with it.
What is duration of drying out for 400 kv transformer?
kVA,400 kVA,630 kVA,800 kVA). continued for 36 hours.
What is over excitation protection?
The overexcitation protection function is applied to protect generators and unit transformers against high flux values causing saturation of the iron cores and consequently high magnetizing currents.
What is OSR in transformer?
The protective Oil Surge Relay (OSR) is used to protect the malfunction developed inside the On Load Tap Changer (OLTC). This protective relay triggers the tripping circuit when the oil flow exceed the specified limits, thus making the transformer to be turned off and contain the damager to the OLTC and Transformer.
How do you calculate frequency from voltage?
The frequency of the voltage is symbolized by f and given by f = 1/T. In terms of ω, f = ω/2π, in hertz.
What is volts per Hertz (V/Hz)?
The ratio of per unit voltage to per unit frequency reffered to as volts per hertz (V/Hz) is a readily measured quantity that is proportional to magnetic flux. Typical V/Hz limitations gor generator (GEN) and step up transformer (XFMR) are shown in following chart. This above curve shows the permissible operating time versus (V/Hz) for generator.
What is the maximum over flux in a transformer?
I.S. specification for electrical power transformer does not stipulate the short time permissible over excitation, though in a round about way it does indicate that the maximum over fluxing in transformer shall not exceed 110\%. The magnetic flux density is, therefore, proportional to the quotient of voltage and frequency (V/f).
What are the factors affecting the V/Hz ratio of a transformer?
The controlling factor is the iron thickness the windings are wrapped around. This also holds true for induction motors. The V/Hz ratio comes into play when the frequency applied to a transformer is changed. The inductive impedance of the coil is dependent on the applied frequency. As frequency decreases, the coil impedance also decreases.
What is the purpose of 24V voltage per herzt limiter?
Voltage per Hertz (Relay 24) Voltage per herzt limiter and protection are used to protect the generator and step-up transformer from damage due to excessive magnetic flux resulting from low frequency and/or overvoltage.