Testing of Stability of Transformer Differential Scheme

basicelectricaldesign
Testing of stability of transformer differential Scheme

Guidelines of transformer differential stability check Transformer above 2 MVA are normally provided with differential protection scheme. The relay can be of static type(DTH31- Alsthom) or numerical type( 7 UT- Sag ) The relays have to be tested as per the procedure mentioned in manuals.The procedure mention below enables the testing engineer to confirm the correctness wiring. Expected short circuit current can be calculated from the % impedance of the transformer. e.g. Consider a transformer of 10 MVA, 132 KV /11 KV, % impedance – 13 % Calculated primary full load current…

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Commissioning of isolators and earthing switches

basicelectricaldesign
Commissioning of isolators and earthing switches

Guidelines of Commissioning of isolators Some of the important guidelines to be followed before energizing the isolators and earthing switches. For your reference, please find below the step by step process of commissioning of isolators: Isolators can be of the following types Centre break Double break Pantograph Operation of isolators can be motorized or manually operated. The nameplate details of an isolator consists of rated current, rated voltage, short circuit current rating, the auxiliary voltage required for operation etc. For a motorized isolator closing & opening is normally controlled by ‘close’,…

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Commissioning Procedure for Electric HT Motor

basicelectricaldesign
Commissioning Procedure for Electric HT Motor

Quick Guidelines of Industrial Electric HT Motor Pre-Commissioning checks:- Check for the proper fixing motor on the foundation. Check that the motor can be easily turned over by hand. Check motor winding resistance on each phase; verify that they are equal. IR value and PI value of the motor to be checked. IR values and HV test on the cable to be performed. Check all the tripping and alarm signals from winding and bearing TRDs (through scanner if provided) Testing of ht motor protection relay and tripping of the circuit breaker…

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Commissioning Procedure for HV / HT Cable

basicelectricaldesign
HT-CABLE

Step by step Commissioning guidelines of HV/ HT Cable Check continuity of the HT cable to confirm R, Y  and B phase at both ends as per marking. This is especially important when there is more than one run of cable phase; any cross-over will result in a dead  short circuit. The Cable screen is to be earthed at one end only. Cable gland plate should be of non- magnetic type e.g. aluminum. Perform HV / HT test on the cable.Apply only Dc voltage, as cables have relatively higher capacitance. Check…

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Electrical Testing and commissioning -Safety Guidelines

basicelectricaldesign

Risk and Safety assessment for Electrical Testing and Commissioning Safety of testing and construction personnel should be the primary  consideration at all times. The following are some guidelines to ensure safety :   Ensure that proper safety gear is used. These include safety shoes, safety helmet, safety gloves(Rubber-Electrical), Rubber mat, fire extinguishers etc Whenever work is dine on power circuits (LT or HT), all power sources must be isolated by opening and withdrawing the circuit breakers. Earthing switches should be closed or if not available local  earthing should be done.…

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