Category Archive for: «Testing and Commissioning»

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General Guidelines for Online Partial Discharge Testing of Power Cables

Faults in the cable insulation Online PD testing is becoming the topic of interest for power cable owners to ensure the safe and continuous operation of power cables. If PD source is detected timely in the cable system, it could save the huge cost of unplanned outage to Plant owners. Regular periodic or continuous monitoring […]

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Impulse withstand voltage test performed on assemblies

Rated impulse withstand voltage Only optional in the past, the impulse test which allow defining the rated impulse withstand voltage Uimp, is now a necessity thus demonstrating the strategy of the Standards directed to increasing the importance of such performance. In addition to the ordinary temporary overvoltages, usually incoming from the supply line, the plants […]

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Do Not Energize Oil-Filled Transformer Without Performing These 15 Tests and Checks!

Obligatory Checklist The following tests and checks should be performed at a minimum to ensure that the transformer is ready to be energized. Do not energize the transformer without performing these tests and checks. If any of below explained tests fail and transformer is energized anyway, it may lead to the serious hazard, and that’s […]

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Basic Transformer Routine Test – Measurement of Winding Resistances

Purpose of the measurement The resistance between all pairs of phase terminals of each transformer winding are measured using direct current. Furthermore the corresponding winding temperature is measured. The measured resistances are needed in connection with the load loss measurement when the load losses are corrected to correspond to the reference temperature. The resistance measurement […]

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Inspection, Test and Measurement Procedures for LV and MV (up to 36kV) Switchgears

Importance of checks and maintenance Installed in clean, well ventilated or air-conditioned locations, switchgear will require little routine maintenance. Major inspection should be scheduled for power plant shutdowns and concentrate for low voltage switchboards on identifying contact wear, correct operation of interlocks, correct overload settings and fuse sizes, signs of overheating, and undue dirt or corrosion. For MV […]

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Test On 110kV Power Cable After Installation (3)

General description of site test procedure In previous two parts of this technical article first six procedures were explained. Now the last three (7, 8 and 9) will be explained in details: Phase indication test (part 1) DC conductor resistance measurement (part 1) Capacitance test (par 1) DC Sheath test on outher sheath (part 2) Insulation resistance […]

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Test On 110kV Power Cable After Installation (2)

General description of site test procedure In previous part of this technical article first three procedures were explained. Now the rest will be explained in details: Phase indication test (previous part) DC conductor resistance measurement (previous part) Capacitance test (previous part) DC Sheath test on outher sheath Insulation resistance measurement Cross bonding check Zero sequence and […]

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Test On 110kV Power Cable After Installation (1)

General description of site test procedure Site test procedure covers all necessary electrical testing for the 110 kV cable and accessories to be carried out during and after installation of the cable system. 110 kV, 115 kV and 132 kV XLPE Cables (Standard Reference is IEC 60840 and relevant SEC Transmission Specifications 11-TMSS-02, Rev. 0 […]

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Transformer Routine Test – Partial Discharge Measurement

Transformer insulation structure This routine test aims to measure the partial discharges which may occur in the transformer insulation structure during test. Partial-discharges are electrical arks which form the surges between electrodes of any area of the insulating media of a transformer between the conductors. These discharges may occur in air bubbles left in the […]

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Testing of Power Transformer – Measurement of Zero-Sequence Impedance

Earth-fault protection Purpose of the measurement The zero-sequence impedance is usually measured for all star-connected windings of the transformer. The measurement is carried out by supplying a current of rated frequency between the parallell connected phase terminals and the neutral terminal. The zero-sequence impedance per phase is three times the impedance measured in this way. […]

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