Category Archive for: «Testing and Commissioning»

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12 Transformer Factory Tests Briefly Explained

Factory tests The remainder of the twelve factory tests are briefly summarized below. The details of the test set connections and formulas of some of the listed tests are already described in separatly published articles, and for the rest you are directed to ANSI/IEEE Standard C57.12.90 for these details. This list is not complete, there […]

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5 Components of Current Drawn by the DC Voltage Testing of Insulation

Current drawn by the insulation When DC voltage is applied to an insulation, the electric field stress gives rise to current conduction and electrical polarization. Consider an elementary circuit as shown in Figure 1 below, which shows a DC voltage source, a switch, and an insulation specimen. However, this current immediately drops in value, and […]

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Procedure for Transformer Lightning Impulse Test

Purpose of the test The purpose of the impulse voltage test is to secure that the transformer insultations withstand the lightning overvoltages which may occur in service. Testing equipment Impulse generator Where: C1 – Impulse capacitor Rc – Charging resistor Rs – Series resistor Ra – Low-ohmic discharging resistor for switching impulse, Rb – High-ohmic discharging resistor for […]

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Maintenance and testing of the overcurrent protective devices

Electrical system reliability When designing electrical distribution systems, required maintenance and testing of the overcurrent protective devices is a very important consideration. The electrical system reliability, component and circuit protection, and overall safety are directly related to the reliability and performance of the overcurrent protective device and can depend upon whether the required testing and […]

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What To Check When Commissioning Variable Speed Drives

The purpose of commissioning VSDs The main purpose of commissioning VSDs is to ensure that: The AC converter and motor have been correctly installed and meet the wiring and safety standards such as IEC 60364 or Australian standard AS 3000. The power and motor cables are correctly sized, installed and terminated. All power cable shields […]

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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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