Category Archive for: «Testing and Commissioning»

Six core activities in the commissioning of the earthing system

Testing of the earthing system Commissioning of new earthing system is essential as a validation step for the design and installation process and for the design inputs. In most cases commissioning should measure the outputs of the earthing system in terms of produced voltages and current distributions rather than solely resistance. The commissioning should consider […]

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18 Initial Checks Of Electrical Installations Every Electrician MUST Perform

Testing of electrical installations // Before any testing of low voltage electrical installations (and equipment) is carried out, a detailed physical inspection must be made to ensure that everything is: To a relevant National or Harmonized European Standard Erected/installed in compliance with the IEE Regulations Not damaged in such a way that it could cause […]

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DC Testing Methods Conducted On Solid Insulation

DC Testing Methods // Let’s take a look at the two important tests that are conducted with DC voltage. Two tests can be conducted on solid insulation using following DC testing methods // Insulation resistance testing High-potential (Hi-pot) voltage testing 1. Insulation Resistance Testing This test may be conducted at applied voltages of 100–15,000 V. […]

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Guidelines For Installing Power Transformers

Operation of power transformers // When your transformer arrives on site, various procedures should be carried out to assure successful operation (installation, testing and various checkings). The successful operation of a transformer is dependent on proper installation as well as on good design and manufacture. The instructions mentioned in the manufacturer manual or in Standards […]

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How electricans test continuity of protective conductors

Testing protective conductors For all protective conductors, including main and supplementary bonding conductors, electricians must perform continuity test using a low-reading ohmmeter. For main equipotential bonding, there is no single fixed value of resistance above which the conductor would be deemed unsuitable. Each measured value, if indeed it is measurable for very short lengths, should […]

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4 Test Instruments Most Frequently Used By Electricians

Testing an electrical installation // The test instruments and test leads used by the electrician for testing an electrical installation must meet all the requirements of the relevant regulations. The HSE has published Guidance Notes GS 38 (download below) for test equipment used by electricians. The IEE Regulations (BS 7671) also specify the test voltage […]

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Guidelines To Inspection Of Molded Case Circuit Breakers (MCCB)

NEMA AB 4 and MCCB maintenance The need for inspection of molded case breakers (MCCB) will vary depending on operating conditions. Suggested inspection and testing is defined in ANSI/NEMA AB 4, Guidelines for Inspection and Preventive Maintenance of Molded Case Circuit Breakers Used in Commercial and Industrial Applications. As part of these guidelines, AB 4 […]

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Connections For Testing Insulation Resistance Of Electrical Equipment

Testing Insulation Resistance // The following schemes show how to connect a Megger insulation tester to various types of electrical equipment. The schemes also show in principle how equipment must be disconnected from other circuits before the instrument is connected. These illustrations are typical and will serve as guides for testing insulation resistance of practically all types of apparatus […]

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Testing Challenges in Large Ground Systems

Large Ground Systems Accurately Measuring Earth Resistance Large ground systems, such as those found in substations and power stations, are an important part of the protection of the electricity supply network. They ensure that fault current will enable protective devices to operate correctly. A substation must have a low ground resistance to reduce excessive voltages […]

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8 Recommended Periodic Inspections of a Substation Transformer

Medium power transformer routine maintenance The following periodic tests and inspections are recommended for routine maintenance of the medium power substation transformer. Gauge readings Cooling fans Control wiring Paint finish Fluid dielectric test Bushing and surge arrester insulators Bushing terminals Gaskets 1. Gauge readings One month after initial energization and annually thereafter Gauge readings, ambient […]

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