IEEE 30004.1-2013 pdf free

IEEE 30004.1-2013 pdf free.IEEE Recommended Practice for the Application of Instrument Transformers in Industrial and Commercial Power Systems.
For the purposes of this document, the following tenns and definitions apply. The JEFF Siandardc Diciionari’ Online should be consulted for terms not defined in this clause.4
burden: Thc load connected to the secondary tcnninals, which may be expressed as voltampcrcs and power factor at a specified value of current, total ohms impedance and power factor, or ohms of the resistance and reactive components.
composite error: The root-mean-square (rms) of the instantaneous difference between the actual primary current and the actual secondary current multiplied by the rated current transformer transformation error.
current transformer (CT): Transforms line current into values suitable for use with standard protective relays and meters while isolating these instruments from line voltages.
dynamic current rating (Id.): The crest value of the asymmetrical primary current which a current transformer must withstand without being damaged electrically or mechanically by the resulting electromagnetic forces with the sceondaryw inding short-circuited.
knee-point oltage: (A) The voltage at which a line tangent to the secondary excitation characteristic, when drawn on log-log coordinates, is at an angle of 450 to the horizontal. (B) The rated-frequency secondary voltage above which a 10% increase in voltage results in an increase of 50% or more in exciting current. (adapted from IEC)
polarity: The instantaneous phase relationship between the currents flowing in the primary and secondary of a current transformer. In simple applications, polarity is not important. but it is a critical consideration whenever multiple current transformers are used in combination, or when the output of a current transformer is used in conjunclion with the output of a voltage transformer.
rating: The rating of a current transformer consists of a primary current rating and an associated secondary current rating. These ratings are related by the nominal transformation ratio of the current transformer. which is usually also the physical turns ratio of the transformer.
ratio correction factor (RCF): The ratio of the true. or measured, ratio of the current transfonner to the marked, or nominal, ratio.
ratio error: The degree to which the ratio correction factor deviates from the ideal, or textbook case, and is typically expressed in percent.
short-time thermal current rating: The maximum current that the current translbrmcr can carry for a specified period of time,
transformer correction factor (TCF): Takes into account both the magnitude of error and any associated error in phase angle. TUF tends to be more of a concern in metering applications and is the factor by which the reading of a wattmeter may be adjusted to compensate for inaccuracies.
voltage transformer (VT): Transforms line voltage into values suitable for standard protective relays and meters while isolating these instruments from the stresses associated with the primary power system.
4. Current transformers
A current transformer (CT) transforms line current into values suitable for use with standard protective relays and meters while isolating these instruments from line voltages. A typical CT has two windings. designated as primary and secondary, which are insulated from each other. Most CTs are conventional in the sense that they are transformers consisting of winding on iron cores. However, air core Cl’s have been used in power system applications, and UTs utilizing optical technology are becoming available. The primary winding is connected in series with the circuit carrying the line current In be measured; and the secondary winding is connected to protective devices, instruments. meters. or control devices.
ldcally. CTs change the magnitude of the current being measured without changing the phase angle or wave shape of the current. Practically, however, the output of CTs does contain some error and distortion, and dealing with these errors and distortion is one of the primary challenges in applying Cl’s.
4.1 Equivalent circuit for current transformers
To understand the performance and application of CTs, it is necessary to start with an equivalent circuit. The circuit shown in Figure 1 is representative, although variations on this circuit may he found in various texts.IEEE 30004.1 pdf download.