High-voltage transformers are some of the most important (and affect the amount of testing necessary to certify that a transformer is ready to. DOI: /RG Transformer is a static device which transforms A.C electrical power from one voltage to another Voltage keeping The frequency same by Electromagnetic induction. REGULAR MAINTENANCE FOR POWER. Many of the details of a complete and effective testing procedure can be obtained from this source. Transformer Testing and Maintenance.
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TRANSFORMER testing manual usaascvb.info - Free download as PDF File .pdf), Text File .txt) or read online for free. IEEE C—IEEE Standard Test Code for Liquid-Immersed specialized equipment including multi-voltage test transformers, a high. The structure of the circuit equivalent of a practical transformer is developed rise of the transformer is required, then test method is the most dependable one.
In some cases this may take several minutes depending upon the winding impedance. Large values may cause inaccuracy by heating the winding and thereby changing its resistance. For Calculating resistance, the corresponding temperature of the winding at the time of measurement must be taken along with resistance value. Required Precaution: According to IEC , in order to reduce measurement errors due to changes in temperature, some precautions should be taken before the measurement is made.
For Delta connected Winding: for delta-connected transformer, the resistance should be measured for each phase i. Delta is composed of parallel combination of the winding under test and the series combination of the remaining winding. It is therefore recommended to make three measurements for each phase to-phase winding in order obtain the most accurate results.
For Dry type transformers: the transformer shall be at rest in a constant ambient temperature for at least three hours. For Oil immersed transformers: the transformers should be under oil and without excitation for at least three hours.
In case of tapped windings, above readings are recorded at each tap. In addition, it is important to ensure that the average oil temperature average of the top and bottom oil temperatures is approximately the same as the winding temperature. Average oil temperature is to be recorded.
Measured values are to be corrected to required temperatures. As the measurement current increases, the core will be saturated and inductance will decrease.
In this way, the current will reach the saturation value in a shorter time.
After the current is applied to the circuit, it should be waited until the current becomes stationary complete saturation before taking measurements, otherwise, there will be measurement errors. In this way, 60 Hz transformers can also be tested at 50 Hz.
The shape of the voltage should be single phase and sinusoidal as far as possible. This test is applied to the star point neutral point of uniform insulated windings and gradual non- uniform insulation windings. Every point of the winding which test voltage has been applied is accepted to be tested with this voltage. The insulation tests of the input terminals phase inputs of the gradual insulation windings is completed during induced voltage test.
Section 7. The test voltage is measured with the help of a voltage divider.
The test voltage should be read from voltmeter as peak value divided by 2. Test period is 1 minute. All the terminals of the winding under test should be connected together and the voltage should be applied here.
Meanwhile, the terminals of the non tested windings should be connected together as groups. Non-tested windings, tank and the core should be earthed.
The secondary windings of bushing type current transformers should be connected together and earthed. The current should be stable during test and no surges should occur. It can not be copied or duplicated without prior permission. There shall be modifications to this document.