power systems loss

VOLTAGE TRANSFORMERS ROUTINE TEST PROCEDURE C57.13.5 Test procedures for voltage transformers. Applied voltage test on the neutral terminal With the ground link temporarily removed from the neutral terminal of the transformer, a voltage of 19 kV (r.m.s.) shall be applied between the neutral terminal and the ground for 60 s. The gas pressure of the gas-filled transformer may be at any setting equal to or less than the pressure given in Clause 5 for the test. The transformer shall be considered as having met the requirements if no external and internal disruptive discharge or collapse of voltage is observed. Accuracy test The test shall be performed in accordance with 8.1 of IEEE Std C57.13-1993. The calibration of the test system given in 4.3 shall apply. The gas pressure of the gas-filled transformer may be at any setting for the test. The transformer shall be considered as having met the requirements if the performance is within the limits of the accuracy class. Excitation ch

CURRENT TRANSFORMERS ROUTINE TEST PROCEDURE C57.13.5 Test procedures for current transformers. Inter-turn overvoltage test The test shall be performed in accordance with one of the following procedures. If there is no agreement between the manufacturer and user, the choice of the procedure shall be left to the manufacturer. If secondary protective devices are provided, these devices shall be installed for the inter-turn overvoltage test. Procedure A With the secondary windings open-circuited (or connected to a high impedance device which reads the peak voltage), a substantially sinusoidal current shall be applied to the primary winding. The test current shall be increased until one of the following conditions is reached:    a) The r.m.s. value of the applied current is equal to the maximum primary current corresponding to the continuous thermal current rating factor (RF), or    b) The peak value of the secondary induced voltage is equal to:       1) 280 V for metering rated cur

STANDARD REQUIREMENTS IN DEALING WITH VOLTAGE TRANSFORMERS What is a Voltage Transformer with respect to C57.13? Terms in which ratings shall be expressed The ratings of a voltage transformer shall include:      a) Basic impulse insulation level in terms of full-wave test voltage      b) Rated primary voltage and ratio      c) Frequency (in Hertz)      d) Accuracy ratings      e) Thermal burden rating Standard burdens Standard burdens for voltage transformers for rating purposes are shown in table below. Assignment of accuracy ratings A voltage transformer shall be assigned an accuracy rating for each of the standard burdens for which it is rated. For example, an accuracy rating might be 0.3W and X, 0.6Y, 1.2Z. Accuracy classification for voltage transformers with two secondary windings or tappedsecondary windings - The burden on any two secondary terminals affects the accuracy on all other terminals. The burden stated in the accuracy ratings is the total burden on the

STANDARD REQUIREMENTS IN DEALING WITH CURRENT TRANSFORMERS What is a Current Transformer with respect to C57.13? Terms in which ratings shall be expressed The ratings of a current transformer shall include:     a) Basic impulse insulation level in terms of full-wave test voltage.     b) Nominal system voltage, or maximum system voltage.     c) Frequency (in Hertz)     d) Rated primary and secondary currents.     e) Accuracy classes at standard burdens.     f) Continuous thermal current rating factor based on 30 °C average ambient air temperature.     g) Short-time mechanical current rating and short-time thermal current rating. Standard burdens Standard burdens for current transformers with 5 A rated secondary current shall have resistance and inductance according to table below. Accuracy ratings for metering A current transformer for metering shall be given an accuracy rating for each standard burden for which it is rated. For example, the accuracy ratings assigned to

TRANSFORMER HANDBOOK: ABB This Transformer Handbook prepared by ABB contains a wide range of power and distribution transformers that aims to serve as a guide in understanding, selection, ordering, operation and maintenance of this transformers. The construction of this devices follows standards to the likings of the customers including but not limited to IEC, CENELEC, and ANSI/IEEE. This Handbook although focuses on ABB products, does not significantly differs to the common practice in specifying transformers and ABB based this handbook on their knowledge and experience. Listed below are the main topics that were discussed in this handbook: Every point found in the list are carefully considered. Also, a portion of this handbook tackles all the available standards that are relevant to transformer information. Transformer Types and their Application Quality, Internal Control, Sustainability Loss Capitalization and Optimum Transformer Design Information Required with Enquiry and Ord