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[ { "title": "ENQUIRE | Siemens Switchgear Demo Bus", "nid": "553", "body": "\u003Cp\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Siemens%20Demo%20Bus\u0022\u003E\u003Cimg alt=\u0022Siemens switchgear demo bus\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u0022bce6988a-2fe0-45cd-bdef-421ae9f565fa\u0022 height=\u0022315\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/20191108_162005.jpg\u0022 width=\u0022560\u0022 class=\u0022align-center\u0022 /\u003E\u003C/a\u003E\u003C/p\u003E\n\u003Cp\u003EInnovation comes right to your doorstep in one convenient place... Hop aboard the Siemens demo bus to view their latest products and solutions in switchgear...\u003C/p\u003E\n\u003Cp\u003E\n\u003Cstrong\u003EDate: Monday 11 October 2021\u003C/strong\u003E\u003Cbr /\u003E\n\u003Cb\u003E\u003Cstrong\u003ETime: 09h00 - 12h00\u003C/strong\u003E\u003Cbr /\u003E\n\u003Cstrong\u003EVenue: Magnet Head Office, Durban\u003C/strong\u003E\u003C/b\u003E\u003C/p\u003E\n\u003Cp\u003E\nSpace is limited. \u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Siemens%20Demo%20Bus\u0022\u003E\u003Cstrong\u003EENQUIRE \u003C/strong\u003E\u003C/a\u003Enow to book your visit!\u003C/p\u003E\n", "created": "Oct 2021", "terms": "Electrical, Products, Siemens" }, { "title": "LEARN | The Importance of Solar System Design pt 2", "nid": "551", "body": "\u003Cp class=\u0022text-align-justify\u0022\u003EIn our NEW series, we unpack the importance of solar system design, and what it involves. In part one, we looked at Mechanical Design, outlining the key design attributes, and their relationships with performance modelling calculations.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EIn part two, we give you a basic understanding of the electrical portion of solar system design\u2026\u003C/p\u003E\n\u003Cp\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Solar Enquiry\u0022\u003E\u003Cimg alt=\u0022Solar panels\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u00223d11d581-5f18-4aab-8193-4dfd16c3df35\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/inline_image_preview.jpg\u0022 class=\u0022align-center\u0022 /\u003E\u003C/a\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003EUnderstanding Electrical Design\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe electrical design of the array determines the electrical behaviour of the array: the powers and voltages that the system will be running at. This can have a major impact on the system\u0027s energy production.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E1. String Size and Voltage\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe number of modules in series (known as the \u201Cstring size\u201D) will determine the voltage of the strings. Voltages add in series \u2013 so the longer the string, the higher the string voltage. Any inverter has an input voltage range for the DC voltages that it can accept from the array. As long as the string voltages are within that inverter\u2019s operating voltage range, the inverter will operate normally.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EBeware of thinking just in terms of STC: the string voltage will drift up and down depending on the temperature of the modules. The module\u2019s temperature coefficient will indicate exactly how the values for Vmp and Voc will move based on the module temperature. Note that the value for the temperature coefficient is always negative: higher temperatures will reduce voltages, while lower temperatures will raise voltages.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EIf a design results in under-voltage or over-voltage at the inverter, this can result in production losses, sometimes significant. If the array is moderately outside of the inverter\u2019s voltage range (typically on the low end), then the inverter will peg at its minimum voltage, and will end up running the modules at a higher voltage than their MPP voltage. So this is technically mismatch loss, since the modules are not running at their peak power. If the string voltage is further outside of the inverter\u2019s operating range, then the string may collapse completely, and will not be able to deliver any power at all at the inverter\u2019s minimum voltage.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003ECodes often mandate a maximum system voltage, and so the string voltage must always be below this value, even on the coldest day. Values for max system voltage are typically 600V, 1000V, or potentially higher \u2013 but consult with your local inspector for guidance here.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E2. Conductor and Combiner Design\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EEach string of modules must be connected to their corresponding inverter by a set of wires, and often a combiner box. As a result, each module string has a specific conductor path from the modules to the inverter connection. Based on the wire used, and the distance that must be covered by that wire, each string home run will have a specific resistance value.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EWire losses are based on the standard equation (I2R), and are modelled based on the specific resistance of each home run, and the hourly current of the module string. The conductors will also lead to voltage drop between the modules and the inverter: the modules will have to run at a slightly higher voltage than the inverter\u2019s draw voltage. In extreme cases, this can potentially cause under-voltage problems at the inverter, and/or parallel mismatch between strings.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E3. Inverter Load Ratio\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u00A0\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA solar array\u2019s Inverter Load Ratio (ILR) is the ratio between the DC nameplate power (defined as the sum of the module DC power at STC) and the AC power (defined as the inverter maximum AC power production).\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EILR values are usually greater than 1.0 (meaning that the DC system power is greater than the AC power), often between 1.1-1.3, and sometimes higher. This is because modules rarely generate at their nameplate power level, mainly because the sun is rarely at full strength, and when it is, it is typically hotter than 25 degrees C. This is why the Normal Operating Conditions (NOCT) values are used. Additionally, there are resistive losses between the surface of the module and the inverter \u2013 specifically, wire losses, mismatch losses, and converter losses if there are any DC-DC electronics installed in the array. So in order to have the DC system and AC system appropriately matched, the design will call for the DC power to be 10-20% higher than the AC power.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EMore recently, higher Inverter Load Ratios have begun to increase in popularity, with some designed values approaching or surpassing 1.5. These designs will clip power at the peak of the day, but will result in more generation at the \u201Cshoulders\u201D of the day (late morning and late afternoon). These designs are generally driven by very inexpensive modules, systems with limits to their AC power rating, or time-of-use pricing regimes.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E4. Inverter Choice\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe inverter choice also has a major impact on a system\u2019s performance. An inverter\u2019s efficiency losses (typically 2-5%) are one of the larger efficiency losses in the system. Additionally, the DC input voltage window for the inverter will determine the potential string sizes that can be designed. Finally, the size and location of the inverter will determine the distances between the modules/combiner boxes and the inverter \u2013 and will therefore determine the wire content and wiring losses.\u003C/p\u003E\n\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022caption caption-img align-center\u0022\u003E\n\u003Ca href=\u0022https://shop.magnetgroup.co.za/#!category/inverters\u0026amp;id=A9BC3011-099B-4175-98AF-A2E569BD4FBA#group=back-up-power\u0022\u003E\u003Cimg alt=\u0022Inverter available on Magnet Store\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u002249089fa4-9260-498e-b503-ae228d030498\u0022 height=\u0022176\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Inverter.jpg\u0022 width=\u0022119\u0022 /\u003E\u003C/a\u003E\n\u003Cfigcaption\u003ESolar Inverter\u003C/figcaption\u003E\n\u003C/figure\u003E\n\u003C/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResources:\u003C/strong\u003E\u003C/p\u003E\n\u003Cp\u003E1. \u003Cstrong\u003E\u003Ca href=\u0022https://shop.magnetgroup.co.za/#!items/inverters\u0026amp;id=F6ED6B2C-027F-4B40-81BF-7753FFE6467C\u0022\u003ESHOP\u003C/a\u003E\u003C/strong\u003E our range of inverters on the Magnet Store\u003C/p\u003E\n\u003Cp\u003E2. \u003Cstrong\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Solar%20Enquiry\u0022\u003ECHAT\u003C/a\u003E\u003C/strong\u003E to our experts for a solar design for your facility\u003C/p\u003E\n\u003Cp\u003E\u00A0\u003C/p\u003E\n\u003Cp\u003ESource:\u003C/p\u003E\n\u003Cp\u003E\u003Ca href=\u0022http://www.folsomlabs.com/modeling#systemdesign\u0022\u003Ehttp://www.folsomlabs.com/modeling#systemdesign\u003C/a\u003E\u003C/p\u003E\n", "created": "Oct 2021", "terms": "Solar, Education" }, { "title": "LEARN | The Importance of Solar System Design pt 1", "nid": "550", "body": "\u003Cp class=\u0022text-align-justify\u0022\u003EDid you know that the efficiency (energy yield) of a \u003Ca href=\u0022https://www.magnetgroup.co.za/solutions-solar/index.php\u0022\u003E\u003Cstrong\u003Esolar system\u003C/strong\u003E\u003C/a\u003E is largely affected by the design of the system? The component choice will drive the behaviour of the module(s) and inverter(s). The orientation of the modules will drive the sun angles at each hour of the year, and therefore the total energy yield of the array. And the electrical design (module stringing, conductor sizes, etc.) will determine the system voltages, which impact wire losses and inverter efficiency.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EIn our NEW series, we unpack the importance of solar system design, and what it involves. In part one, we look at Mechanical Design, outlining the key design attributes, and their relationships with performance modelling calculations.\u003C/p\u003E\n\u003Cp\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Solar Enquiry\u0022\u003E\u003Cimg alt=\u0022mechanical design\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u0022646911fb-142a-43d5-9af4-7558f7e91975\u0022 height=\u0022238\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/solar-energy-worker-newsletter.jpg\u0022 width=\u0022476\u0022 class=\u0022align-center\u0022 /\u003E\u003C/a\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003EUnderstanding Mechanical Design\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe mechanical design attributes are the most visible parts of a solar array. This section gives an overview of module choice (which modules are used, how many are installed), module orientation (how they are structured \u0026amp; oriented) and ends off with module spacing.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E1. Module Choice\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe specific module used on a project has a major impact on the overall design. The module form factor (size and weight) will determine the number of modules that can be designed on a system. The efficiency of the module (and therefore the module\u2019s rated power) determine the nameplate power for the system. And finally, the voltage and current rating of the module determines the electrical system designs, including how many modules can be wired in series, and how the strings must be fused. And of course, the cost of the module is a major driver in determining a project\u2019s financial returns.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EAdditionally, other factors, such as temperature coefficient, fill factor, low-light performance, and binning tolerance, can all have an impact on a system\u2019s energy performance. The relative importance of these factors will depend on the size and location of an array.\u003C/p\u003E\n\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022caption caption-img align-center\u0022\u003E\n\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Solar Enquiry\u0022\u003E\u003Cimg alt=\u0022fig 1\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u002238a85f80-763f-427f-a4a8-ab17e9ed161b\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Fig%201_Solar%20Module%20Specifications.jpg\u0022 /\u003E\u003C/a\u003E\n\u003Cfigcaption\u003E\u003Cem\u003ESolar Module Specifications \u003C/em\u003E\u003C/figcaption\u003E\n\u003C/figure\u003E\n\u003C/p\u003E\n\u003Cp\u003E\u00A0\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E2. Module Orientation\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA module\u2019s orientation in a fixed-tilt array is given by its tilt and azimuth angles. These two measures define the direction of the collector\u2019s face:\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EAzimuth defines the direction on a compass that the module is oriented. A zero degree azimuth corresponds to due North, 90 degrees will face East, 180 degree azimuth corresponds to due South.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003ETilt defines the angle of incline of the module, with zero corresponding to completely flat, and 90 degrees corresponding to completely vertical.\u003C/p\u003E\n\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022caption caption-img align-center\u0022\u003E\n\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Solar Enquiry\u0022\u003E\u003Cimg alt=\u0022fig 2\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u00222ccda832-a0a4-41a1-bdaa-dabd55864f85\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Fig%202_Module%20Tilt%20and%20Azimuth%20Angles.jpg\u0022 /\u003E\u003C/a\u003E\n\u003Cfigcaption\u003E\u003Cem\u003EModule Tilt and Azimuth Angles \u003C/em\u003E\u003C/figcaption\u003E\n\u003C/figure\u003E\n\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe most common orientation for a solar array would be an azimuth of toward the equator (180 degrees in the Northern Hemisphere) and a slight tilt (tilt of between 5-20 degrees). In some systems, such as tracked systems, these angles will change throughout the day based on the position of the sun.\u003C/p\u003E\n\u003Cp\u003E\u003Cstrong\u003E3. Row-to-row Spacing and Ground Coverage Ratio\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EIn commercial rooftop and ground-mount arrays, the spacing between the rows of modules is a critical design decision, as it has implications for the system size (since tighter spacing means that an array can fit more modules in a given space), and row-to-row shading (since closer racks of modules will shade each other more often).\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA common design metric to evaluate the module spacing is the Ground Coverage Ratio (GCR), which is the ratio of the total module area, divided by the total ground area of the array. GCR values will be below 1.0, often between 0.3 and 0.7. There is an inverse relationship between row-to-row spacing and GCR: as the rows are spaced more closely together, the site ground coverage ratio will increase.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EAs GCR changes, there is generally a trade-off between a system\u2019s nameplate size and its energy yield. Lower GCR values will keep modules spaced far apart, which maximizes their individual production \u2013 however, this will result in a smaller-sized system. Higher GCR values will increase the system size, but will reduce the energy yield from higher cross-bank shading.\u003C/p\u003E\n\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022caption caption-img align-center\u0022\u003E\n\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Solar Enquiry\u0022\u003E\u003Cimg alt=\u0022fig 3\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u00228325a3b2-6699-4009-a6cb-435b83cbab42\u0022 height=\u0022253\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Fig3_Array%20Row%20Spacing.jpg\u0022 width=\u0022779\u0022 /\u003E\u003C/a\u003E\n\u003Cfigcaption\u003E\u003Cem\u003EArray Row Spacing\u003C/em\u003E\u003C/figcaption\u003E\n\u003C/figure\u003E\n\u003C/p\u003E\n\u003Cp\u003E\u003Cstrong\u003E4. System Sizing\u003C/strong\u003E\u003C/p\u003E\n\u003Cp\u003EThe size of a solar array indicates how much power it can deliver at peak conditions. The power level is often referred to as the \u201Cnameplate power\u201D of the array. System sizes are typically given in two different values: the DC power (the number of modules multiplied by their STC power rating), and the AC power (the number of inverters multiplied by their maximum rated AC output power). The ratio between the DC power and AC power is called the \u201CInverter loading ratio\u201D (ILR).\u003C/p\u003E\n\u003Cp\u003E\u00A0\u003C/p\u003E\n\u003Cp\u003EIn the second instalment of the series, we will be discussing the importance of Electrical Design.\u003C/p\u003E\n\u003Cp\u003EConsidering a solar solution for your facility? \u003Cstrong\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Solar%20Enquiry\u0022\u003ECHAT\u003C/a\u003E\u003C/strong\u003E to our experts for assistance now!\u003C/p\u003E\n\u003Cp\u003E\u00A0\u003C/p\u003E\n\u003Cp\u003ESource:\u003C/p\u003E\n\u003Cp\u003E\u003Ca href=\u0022http://www.folsomlabs.com/modeling#systemdesign\u0022\u003Ehttp://www.folsomlabs.com/modeling#systemdesign\u003C/a\u003E\u003C/p\u003E\n", "created": "Sep 2021", "terms": "Solar, Education" }, { "title": "LEARN | Understanding 3-Phase Transformers pt 3 (continued)", "nid": "545", "body": "\u003Cp class=\u0022text-align-justify\u0022\u003EWelcome to your comprehensive guide on Transformers. Before you get started on the final instalment, why not take a moment to catch up on all the articles in this interesting series:\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Ca href=\u0022https://www.magnetgroup.co.za/news.php?type=articles\u0026amp;name=LEARN--Understanding-3-Phase-Transformers-pt-1\u0022\u003E\u003Cstrong\u003EPart 1: Understanding Transformers and how they work\u003C/strong\u003E\u003C/a\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E\u003Ca href=\u0022https://www.magnetgroup.co.za/solutions-electrical/news.php?type=articles\u0026amp;name=LEARN--Understanding-3-Phase-Transformers-pt-2\u0022\u003EPart 2: Advantages, disadvantages and types of 3-Phase Transformers\u003C/a\u003E\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E\u003Ca href=\u0022https://www.magnetgroup.co.za/news.php?type=articles\u0026amp;name=LEARN--Understanding-3-Phase-Transformers-pt-3\u0022\u003EPart 3: \u003C/a\u003E\u003C/strong\u003E\u003C/p\u003E\n\u003Cul\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003E\u003Ca href=\u0022https://www.magnetgroup.co.za/news.php?type=articles\u0026amp;name=LEARN--Understanding-3-Phase-Transformers-pt-3\u0022\u003EProtection Schemes for Oil Type Transformers\u003C/a\u003E\u003C/strong\u003E\u003C/li\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EProtection Schemes for Oil Type Transformers\u00A0continued\u003C/li\u003E\n\u003C/ul\u003E\n\u003Cp\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Electrical Enquiry\u0022\u003E\u003Cimg alt=\u0022Oil type transformer\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u0022ae982d7a-2777-4fa8-a837-9e2c228ca28e\u0022 height=\u0022229\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Oil-Filled-Transformers_0.jpg\u0022 width=\u0022345\u0022 class=\u0022align-center\u0022 /\u003E\u003C/a\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u00A0\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EWe\u2019re wrapping up our series with a second instalment on Protection Schemes for Oil Type Transformers. In this article, we give a basic introduction to the Buchholz relay, its principle of operation, the advantages, and the limitations of having this vital piece of equipment installed on oil-type transformers. This articles also gives a brief explanation of the devices that are used to monitor the oil level and the temperature of the hottest part of the winding in your transformer.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003EBuchholz Relay\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA Buchholz relay is an oil and gas actuated protection relay that is implemented on oil immersed transformers. It is used for the protection of transformers from faults that occur inside it. Short circuit faults, inter-turn faults, incipient winding faults and core faults occur because of an impulse breakdown occurring on the insulating oil or deterioration in the transformer oil itself.\u00A0 The Buchholz relay will sense these faults, and issue a trip signal to the circuit breaker which is either on the HV or LV side of the transformer. This will then enable the circuit breaker to isolate the faulted zone.\u003C/p\u003E\n\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022caption caption-img align-center\u0022\u003E\n\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Electrical Enquiry\u0022\u003E\u003Cimg alt=\u0022Buchholz\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u00228b32d9b5-ef17-481e-9243-8abbbaa543df\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Figure%201_0.png\u0022 /\u003E\u003C/a\u003E\n\u003Cfigcaption\u003EBuchholz Relay and Conservator Location on an Oil-Filled Transformer\u003C/figcaption\u003E\n\u003C/figure\u003E\n\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003EPrinciple of Operation\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA fault that occurs in the transformer will cause the oil in the tank to become overheated, thus producing gas. The generation of the gas in the transformer is dependent on the intensity of the fault that occurred. As a result of this heat, oil in the tank will decompose, and this is used to detect winding faults. The gas then flows in an upward direction and gets collected in the Buchholz relay. This gas decomposes the oil in the Buchholz relay, and this displacement is equivalent to the volume of gas collected. The displacement of oil will result in the upper float closing the upper mercury switch that is connected to an alarm circuit. Therefore, when minor faults occur, the alarm gets activated. The amount of gas that is collected will indicate the severity of the fault. The lower float is unaffected by minor faults as there is not enough gas to move it.\u00A0\u00A0\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA major fault, such as a phase to earth short circuit, will generate a vast amount of heat resulting in a large amount of gas being produced. This gas will also flow in an upward direction but the motion of it will be high enough to tilt the lower float in a Buchholz relay. In the event of a major fault, the lower float will cause the lower mercury switch to trip the transformer from the supply.\u003C/p\u003E\n\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022caption caption-img align-center\u0022\u003E\n\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Electrical Enquiry\u0022\u003E\u003Cimg alt=\u0022CS Diagram of Buccholz\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u00221940d2c8-c611-4eb6-8c57-c91ce11b7cca\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Figure%202_0.png\u0022 /\u003E\u003C/a\u003E\n\u003Cfigcaption\u003ECross Section Diagram of a Buchholz Relay\u003C/figcaption\u003E\n\u003C/figure\u003E\n\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003EAdvantages of a Buchholz Relay\u003C/strong\u003E\u003C/p\u003E\n\u003Col\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EIndicates internal faults that may occur due to heating and helps avoid major faults\u003C/li\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EDetermines the severity of a fault without dismantling a transformer\u003C/li\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EIsolates a transformer if a major fault occurs, thus preventing accidents\u003C/li\u003E\n\u003C/ol\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003ELimitations of the Buchholz Relay\u003C/strong\u003E\u003C/p\u003E\n\u003Col\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EOnly implemented in an oil immersed transformer\u003C/li\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EOnly detects a fault below the oil level\u003C/li\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EOffers no protection for connecting cables, hence separate protection is needed for that\u003C/li\u003E\n\u003Cli class=\u0022text-align-justify\u0022\u003EHigh response time (the minimum operating time of the relay is 0.1 seconds)\u003C/li\u003E\n\u003C/ol\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003EOil Level Monitoring Device\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA transformer that has an oil conservator will often have an oil level monitor installed. This monitor has two contacts for an alarm. One contact is used for the maximum oil level alarm and the other contact is for the minimum oil level alarm.\u003C/p\u003E\n\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022caption caption-img align-center\u0022\u003E\n\u003Cimg alt=\u0022Oil level monitor\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u002215eb9d53-8f16-4375-a205-ea8abb6afcd4\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Figure%203.png\u0022 /\u003E\n\u003Cfigcaption\u003EOil Level Monitor\u003C/figcaption\u003E\n\u003C/figure\u003E\n\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA top-oil thermometer consists of a liquid thermometer bulb that is in a pocket at the top of the transformer. The thermometer is used to measure the top-oil temperature of the transformer. This thermometer can have one to four contacts that sequentially close at successively higher temperatures.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003E\u003Cstrong\u003EWinding Thermometers\u003C/strong\u003E\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EA winding thermometer is a device that responds to both the top-oil temperature and the heating effect of the load current. A winding thermometer leads to the creation of an image that depicts the hottest part of the winding. This top-oil temperature is measured by the procedure mentioned above, but this measurement is expanded with a current signal that is proportional to the loading current in the winding.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe current signal is taken from a current transformer that is installed in the bushing of that winding. A resistor element is fed with this current, causing it to heat up, thus heating up the measurement below and finally resulting in an increased indicator movement.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003EThe temperature bias is directly proportional to the resistance of the electric heating (resistor) element. The bias should correspond to the difference between the hot-spot temperature and the top-oil temperature. The time constant of the heating of the pocket should equal the time constant of the heating of the winding. The temperature sensor will then measure a temperature that is equal to the winding temperature, if the bias is equal to the temperature difference and the constants are equal.\u003C/p\u003E\n\u003Cp class=\u0022text-align-justify\u0022\u003ENeed advice on your transformer?\u00A0\u003Cstrong\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Electrical%20Enquiry\u0022\u003ECHAT\u003C/a\u003E\u003C/strong\u003E\u00A0to us now!\u003C/p\u003E\n", "created": "Sep 2021", "terms": "Electrical, Education" }, { "title": "READ | 10 Dumb things people do when testing Electricity", "nid": "546", "body": "\u003Cp\u003E\u003Ca href=\u0022mailto:hello@magnetgroup.co.za?subject=Fluke Enquiry\u0022\u003E\u003Cimg alt=\u0022Fluke multimeters\u0022 data-entity-type=\u0022file\u0022 data-entity-uuid=\u00220ef4aa6d-7fd6-4b10-98a8-ce76c6ed0319\u0022 src=\u0022/cms/drupal8-magnetgroup/sites/default/files/inline-images/Fluke%20multimeters.jpg\u0022 class=\u0022align-center\u0022 /\u003E\u003C/a\u003E\u003C/p\u003E\n\u003Cp\u003E\u00A0\u003C/p\u003E\n\u003Cp\u003EAnyone who makes their living by working with electricity quickly develops a healthy respect for anything with even a remote chance of being \u0022live.\u0022 Yet, the pressures of the getting a job done on time or getting a mission-critical piece of equipment back on line can result in carelessness and uncharacteristic mistakes by even the most seasoned electrician\u2026\u003C/p\u003E\n\u003Cp\u003EThe list below was developed by FLUKE as a quick reminder of what \u003Cem\u003Enot\u003C/em\u003E to do when taking electrical measurements:\u003C/p\u003E\n\u003Col\u003E\n\u003Cli\u003E\u003Cstrong\u003EReplace the original fuse with a cheaper one\u003C/strong\u003E. If your digital multimeter meets today\u0027s safety standards, that fuse is a special safety sand fuse designed to pop before an overload hits your hand. When you change your meter fuse, be sure to replace it with an\u00A0\u003Ca href=\u0022https://www.fluke.com/en/products/accessories\u0022\u003Eauthorized fuse\u003C/a\u003E.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003EUse a bit of wire or metal to get around the fuse all together\u003C/strong\u003E. That may seem like a quick fix if you\u0027re caught without an extra fuse, but that fuse could be all that ends up between you and a spike headed your way.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003EUse the wrong test tool for the job\u003C/strong\u003E. It\u0027s important to match your\u00A0\u003Ca href=\u0022https://www.fluke.com/en/products/electrical-testing/digital-multimeters\u0022\u003Edigital multimeter\u003C/a\u003E\u00A0to the work ahead. Make sure your test tool holds the correct CAT rating for each job you do, even if it means switching DMMs throughout the day.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003EGrab the cheapest meter on the rack\u003C/strong\u003E. You can upgrade later, right? Maybe not, if you end up a victim of a safety accident because that cheap test tool didn\u0027t actually contain the safety features it advertised. Look for independent laboratory testing.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003ELeave your safety glasses in your shirt pocket\u003C/strong\u003E. Take them out. Put them on. It\u0027s important. Ditto insulated gloves and flame-resistant clothing.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003EWork on a live circuit\u003C/strong\u003E. De-energize the circuit whenever possible. If the situation requires you to work on a live circuit, use properly insulated tools, wear safety glasses or a face shield and insulated gloves, remove watches or other jewellery, stand on an insulated mat and wear flame-resistant clothing, not regular work clothes.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003EFail to use proper lockout/ tag-out procedures\u003C/strong\u003E. Just don\u2019t do it.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003EKeep both hands on the test\u003C/strong\u003E. No\u2026 Don\u0027t! When working with live circuits, remember the old electrician\u0027s trick. Keep one hand in your pocket. That lessens the chance of a closed circuit across your chest and through your heart. Hang or rest the meter if possible. Try to avoid holding it with your hands to minimize personal exposure to the effects of transients.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003ENeglect your leads\u003C/strong\u003E. Test leads are an important component of DMM safety. Make sure your leads match the CAT level of your job as well. Look for\u00A0\u003Ca href=\u0022https://www.fluke.com/en/products/accessories/test-leads\u0022\u003Etest leads\u003C/a\u003E\u00A0with double insulation, shrouded input connectors, finger guards and a non-slip surface.\u003Cbr /\u003E\n\t\u00A0\u003C/li\u003E\n\u003Cli\u003E\u003Cstrong\u003EHang onto your old test tool forever\u003C/strong\u003E. Today\u0027s test tools contain safety features unheard of even a few years ago, features that are worth the cost of an equipment upgrade and a lot less expensive than an emergency room visit.\u003C/li\u003E\n\u003C/ol\u003E\n\u003Cp\u003E\u00A0\u003C/p\u003E\n\u003Cp\u003ETurn to Fluke\u2019s T6-1000 Electrical Tester:\u003C/p\u003E\n\u003Cp\u003E1. \u003Ca href=\u0022https://www.youtube.com/watch?v=16b1xhXFIhA\u0026amp;list=PL0AHvVniUcgzRtFVdw-UbTU1u0FwFgx18\u0026amp;index=1\u0022\u003E\u003Cstrong\u003EWATCH\u003C/strong\u003E\u003C/a\u003E the T6\u00A0Electrical Tester\u003C/p\u003E\n\u003Cp\u003E2\u003Cstrong\u003E. \u003Ca href=\u0022https://www.youtube.com/watch?v=zck6Qz3mM1o\u0026amp;list=PL0AHvVniUcgzRtFVdw-UbTU1u0FwFgx18\u0026amp;index=2\u0022\u003EWATCH\u003C/a\u003E\u00A0\u003C/strong\u003Ethe T6-1000 Pro Electrical Tester\u003C/p\u003E\n\u003Cp\u003E3. \u003Ca href=\u0022https://www.magnet.co.za/external/magnet-fluke-t6-fieldsense.pdf\u0022\u003E\u003Cstrong\u003EDISCOVER\u003C/strong\u003E\u003C/a\u003E Fluke\u0027s FieldSense technology\u003C/p\u003E\n\u003Cp\u003E4.\u003Cstrong\u003E\u00A0\u003Ca href=\u0022https://www.magnet.co.za/contactus.html\u0022\u003ECHAT\u003C/a\u003E\u003C/strong\u003E to us for advice on a Fluke solution for your facility now!\u003C/p\u003E\n", "created": "Sep 2021", "terms": "Electrical, Education, Products, Fluke" } ]