{"id":10759,"date":"2026-08-29T23:43:18","date_gmt":"2026-08-29T15:43:18","guid":{"rendered":"https:\/\/q8bbzjnpm5.wpdns.site\/?p=10759"},"modified":"2026-08-29T23:43:18","modified_gmt":"2026-08-29T15:43:18","slug":"key-points-of-transformer-daily-maintenance-and-troubleshooting-for-common-faults","status":"publish","type":"post","link":"https:\/\/subian-electric.com\/fr\/news\/key-points-of-transformer-daily-maintenance-and-troubleshooting-for-common-faults\/","title":{"rendered":"Points Cl\u00e9s de l'Entretien Quotidien des Transformateurs et du D\u00e9pannage des Pannes Courantes"},"content":{"rendered":"<p>C'est mardi matin \u00e0 6h50 lorsque l'\u00e9lectricien de service d'une usine de taille moyenne r\u00e9alise qu'un transformateur de 2 000 kVA bourdonne beaucoup plus fort que d'habitude. La fen\u00eatre du relais Buchholz pr\u00e9sente une petite poche de gaz, et le manom\u00e8tre d'huile sur le conservateur indique un niveau inf\u00e9rieur \u00e0 celui du mois dernier. Tout le monde conna\u00eet le dicton selon lequel les probl\u00e8mes de transformateurs ne se r\u00e9solvent pas d'eux-m\u00eames, m\u00eame si personne ne veut encore l'appeler une urgence. Certaines des meilleures pratiques de maintenance quotidienne des transformateurs et des m\u00e9thodes de d\u00e9pannage des probl\u00e8mes courants entrent en jeu.<\/p>\n<p>Cet article vous fournira des informations pratiques sur la maintenance quotidienne et r\u00e9guli\u00e8re des \u00e9quipements des transformateurs immerg\u00e9s dans un liquide et des recommandations \u00e9tape par \u00e9tape sur la fa\u00e7on de d\u00e9panner les principales pannes, y compris le bruit soudain, les fuites d'huile, la temp\u00e9rature \u00e9lev\u00e9e de l'huile, le fonctionnement du relais Buchholz, une mauvaise isolation, etc. Vous trouverez des listes de contr\u00f4le, des valeurs d'alarme et normales, des estimations r\u00e9alistes et des \u00e9tapes d'investigation dans l'article.<\/p>\n<blockquote><p>En termes simples, cela signifie que la maintenance quotidienne des transformateurs est un processus simple. Pour \u00eatre maintenu, il n\u00e9cessite de v\u00e9rifier la couleur et le niveau de l'huile, de pr\u00eater attention \u00e0 tout bruit inhabituel, de v\u00e9rifier la temp\u00e9rature, de v\u00e9rifier les connexions des bushing et le relais Buchholz, et de noter toute alarme. Les probl\u00e8mes courants des transformateurs et leurs solutions incluent la v\u00e9rification de la temp\u00e9rature de l'huile, de l'alarme de gaz Buchholz, des fuites d'huile et de la faible r\u00e9sistance d'isolation.<\/p><\/blockquote>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-10760\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/08\/Key-Points-Of-Transformer-Daily-Maintenance-And-Troubleshooting-For-Common-Faults.webp\" alt=\"Key Points Of Transformer Daily Maintenance And Troubleshooting For Common Faults\" width=\"1448\" height=\"1086\" \/><\/p>\n<hr \/>\n<h2 id=\"why-daily\">Pourquoi la maintenance quotidienne est importante<\/h2>\n<p>Les transformateurs peuvent tomber en panne de deux mani\u00e8res : brusquement en raison d'\u00e9v\u00e9nements tels qu'un coup de foudre, des bushing explosant ou un court-circuit ; ou lentement en raison de la d\u00e9gradation de l'isolation, de l'intrusion d'humidit\u00e9 \u00e0 travers les transformateurs et du fonctionnement m\u00e9canique du transformateur. Les pannes lentes sont quelque chose que la maintenance pr\u00e9ventive peut g\u00e9rer car elles donnent des signes avant-coureurs des semaines ou des mois avant que la d\u00e9faillance ne se produise : par exemple, un niveau d'huile plus bas dans le r\u00e9servoir du transformateur, un changement dans le son du transformateur, une augmentation de la temp\u00e9rature du r\u00e9servoir et des fuites d'huile insignifiantes.<\/p>\n<p>Des recherches men\u00e9es par des groupes de travail de l'IEEE et du CIGR\u00c9 montrent que les donn\u00e9es sur les pannes de transformateurs soutiennent la conclusion selon laquelle le syst\u00e8me d'isolation et les changeurs de prises constituent le plus grand nombre des donn\u00e9es totales de pannes de transformateurs, repr\u00e9sentant 30 \u00e0 50 % du nombre total de pannes des transformateurs. Une inspection de cinq minutes chaque jour peut aider \u00e0 identifier les causes des pannes d'isolation FIA, tandis qu'un \u00e9chantillon d'huile annuel co\u00fbtant $300 peut confirmer ce qui se passe \u00e0 l'int\u00e9rieur du r\u00e9servoir du transformateur. Le sc\u00e9nario inverse implique de d\u00e9couvrir la d\u00e9faillance lorsque le dispositif de protection est activ\u00e9, ce qui signifie que des travaux de r\u00e9paration d'urgence doivent \u00eatre effectu\u00e9s, ainsi que des heures suppl\u00e9mentaires et des co\u00fbts h\u00e9rit\u00e9s n\u00e9cessaires pour r\u00e9aliser ces t\u00e2ches, qui d\u00e9passent g\u00e9n\u00e9ralement les co\u00fbts de maintenance de 5 \u00e0 20 fois.<\/p>\n<h2 id=\"daily-checklist\">La liste de contr\u00f4le de l'inspection quotidienne<\/h2>\n<p>Une inspection quotidienne typique d'un transformateur rempli d'huile prend environ 5 \u00e0 10 minutes. Suivez les points ci-dessous tout en veillant \u00e0 un enregistrement appropri\u00e9 :<\/p>\n<ul>\n<li>Niveau d'huile : v\u00e9rifiez un indicateur de niveau d'huile manuel. Une diminution soudaine indique une fuite d'huile et des d\u00e9fauts possibles.<\/li>\n<li>\u00c9tat et ar\u00f4me de l'huile : le verre de contr\u00f4le doit indiquer une huile propre et claire ; une huile trouble signifie de l'humidit\u00e9 ou une carbonisation, respectivement.<\/li>\n<li>Bruit : le transformateur ne doit produire qu'un bourdonnement doux ; tout bruit de bourdonnement indique des pi\u00e8ces desserr\u00e9es, des probl\u00e8mes de noyau ou une activit\u00e9 de d\u00e9charge. Toute alt\u00e9ration du son r\u00e9gulier doit susciter des soup\u00e7ons.<\/li>\n<li>Temp\u00e9ratures : notez le niveau de temp\u00e9rature de l'huile sup\u00e9rieure et comparez-le \u00e0 l'\u00e9tat charg\u00e9. Dans un transformateur de distribution enti\u00e8rement actif, la temp\u00e9rature doit \u00eatre proche de 60 \u00e0 75 \u00b0C par temps normal ; toute lecture sup\u00e9rieure \u00e0 85-90 \u00b0C doit \u00eatre alarmante.<\/li>\n<li>Bagues : recherchez des fissures ou des traces.<\/li>\n<li>D\u00e9shydratateur : le gel de silice doit encore \u00eatre bleu (indiquant un manque d'humidit\u00e9) ; il doit \u00eatre rose ou rouge\u00e2tre.<\/li>\n<li>Relais Buchholz : confirmez qu'il n'y a pas d'accumulation de gaz dans la fen\u00eatre.<\/li>\n<li>Autre chose : consid\u00e9rez la pr\u00e9sence d'huile sous le transformateur, des vibrations inhabituelles, des boulons desserr\u00e9s, etc.<\/li>\n<\/ul>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-10761\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/08\/The-Daily-Inspection-Checklist.webp\" alt=\"La liste de contr\u00f4le de l&#039;inspection quotidienne\" width=\"1448\" height=\"1086\" \/><\/p>\n<p>Toute activit\u00e9 inhabituelle est enregistr\u00e9e et prise au s\u00e9rieux, tandis que l'enregistrement quotidien fournit \u00e9galement des donn\u00e9es de tendance utiles qui peuvent \u00eatre utilis\u00e9es pour des diagnostics futurs. Un carnet de bord standardis\u00e9 et simple rempli \u00e0 chaque occasion permet une vue rapide des tendances :<\/p>\n<table>\n<thead>\n<tr>\n<th>Date<\/th>\n<th>Temp\u00e9rature de l'huile sup\u00e9rieure<\/th>\n<th>Charge<\/th>\n<th>Niveau d'huile<\/th>\n<th>Son<\/th>\n<th>D\u00e9shydratateur<\/th>\n<th>Remarques<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>2026-05-12<\/td>\n<td>63\u00b0C<\/td>\n<td>72%<\/td>\n<td>\u00c0 la marque<\/td>\n<td>Bourdonnement normal<\/td>\n<td>Bleu<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>2026-05-13<\/td>\n<td>67\u00b0C<\/td>\n<td>75%<\/td>\n<td>\u00c0 la marque<\/td>\n<td>Normal<\/td>\n<td>Bleu<\/td>\n<td>Tache d'huile au joint du radiateur<\/td>\n<\/tr>\n<tr>\n<td>2026-05-14<\/td>\n<td>71\u00b0C<\/td>\n<td>78%<\/td>\n<td>\u00c0 la marque<\/td>\n<td>L\u00e9ger bourdonnement<\/td>\n<td>Bleu<\/td>\n<td>Enqu\u00eater sur le bourdonnement, tracer la tache<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 id=\"routine-tasks\">T\u00e2ches de routine hebdomadaires et mensuelles<\/h2>\n<p>Les inspections quotidiennes r\u00e9v\u00e8lent des signes imm\u00e9diats de probl\u00e8mes, tandis que les inspections hebdomadaires et mensuelles aident \u00e0 d\u00e9tecter une d\u00e9t\u00e9rioration plus longue :<\/p>\n<table>\n<thead>\n<tr>\n<th>Fr\u00e9quence<\/th>\n<th>T\u00e2che<\/th>\n<th>Norme \/ Valeur typique<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Hebdomadaire<\/td>\n<td>Inspection visuelle de tous les accessoires, fonctionnement des ventilateurs de refroidissement, v\u00e9rification des fuites d'huile<\/td>\n<td>Pas de fuites, les ventilateurs fonctionnent sur thermostat<\/td>\n<\/tr>\n<tr>\n<td>Mensuel<\/td>\n<td>V\u00e9rifiez le niveau d'huile \u00e0 temp\u00e9rature, inspectez les connexions de mise \u00e0 la terre, nettoyez les surfaces des isolateurs<\/td>\n<td>R\u00e9sistance de mise \u00e0 la terre &lt; 1 \u03a9 l\u00e0 o\u00f9 test\u00e9<\/td>\n<\/tr>\n<tr>\n<td>Trimestriel<\/td>\n<td>Test de r\u00e9sistance d'isolement (megger) sur les enroulements, v\u00e9rifiez le fonctionnement du changeur de prises<\/td>\n<td>Les valeurs IR sont des tendances, pas absolues ; 1 000 \u00e0 5 000 M\u03a9 typiques sur des enroulements HV en bonne sant\u00e9<\/td>\n<\/tr>\n<tr>\n<td>Semi-annuel<\/td>\n<td>\u00c9chantillonnage d'huile pour humidit\u00e9 et r\u00e9sistance di\u00e9lectrique, \u00e9chantillon d'huile OLTC<\/td>\n<td>Tension de claquage &gt; 30\u201340 kV selon IEC 60156 ; humidit\u00e9 &lt; 20\u201330 ppm<\/td>\n<\/tr>\n<tr>\n<td>Annuel<\/td>\n<td>DGA complet, analyse de furanes, test de qualit\u00e9 de l'huile, test de relais de protection<\/td>\n<td>Niveaux de gaz selon IEEE C57.104 condition 1<\/td>\n<\/tr>\n<tr>\n<td>Tous les 3\u20135 ans<\/td>\n<td>Inspection approfondie, r\u00e9vision du conservateur et du filtre, inspection des contacts OLTC<\/td>\n<td>Fabricant et directives IEC 60422<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 id=\"normal-values\">\u00c0 quoi ressemble le \u201c Normal \u201d : Valeurs de r\u00e9f\u00e9rence<\/h2>\n<p>Le diagnostic commence par comprendre quelles sont les valeurs normales. Le tableau ci-dessous repr\u00e9sente les plages de distribution pratiques pour les transformateurs de distribution immerg\u00e9s dans l'huile :<\/p>\n<table>\n<thead>\n<tr>\n<th>Param\u00e8tre<\/th>\n<th>Plage normale<\/th>\n<th>Enqu\u00eater lorsque<\/th>\n<th>Niveau d'alarme \/ d'action<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Temp\u00e9rature de l'huile sup\u00e9rieure (charg\u00e9e)<\/td>\n<td>50\u201375\u00b0C<\/td>\n<td>&gt; 80\u201385\u00b0C<\/td>\n<td>&gt; 90\u201395\u00b0C : r\u00e9duire la charge, v\u00e9rifier le refroidissement<\/td>\n<\/tr>\n<tr>\n<td>Estimation du point chaud des enroulements<\/td>\n<td>&lt; 98\u00b0C selon le guide de chargement<\/td>\n<td>Tendance \u00e0 la hausse<\/td>\n<td>&gt; 110\u2013120\u00b0C : vieillissement s\u00e9rieux<\/td>\n<\/tr>\n<tr>\n<td>Tension de claquage de l'huile<\/td>\n<td>&gt; 40\u201360 kV<\/td>\n<td>30\u201340 kV<\/td>\n<td>&lt; 30 kV : filtration \/ remplacement n\u00e9cessaire<\/td>\n<\/tr>\n<tr>\n<td>Humidit\u00e9 de l'huile<\/td>\n<td>&lt; 15\u201320 ppm<\/td>\n<td>20\u201330 ppm<\/td>\n<td>&gt; 30\u201340 ppm : ass\u00e9cher l'huile et enqu\u00eater<\/td>\n<\/tr>\n<tr>\n<td>R\u00e9sistance d'isolement (megger, enroulement HV)<\/td>\n<td>&gt; 1 000 M\u03a9<\/td>\n<td>Tendance \u00e0 la baisse entre les tests<\/td>\n<td>&lt; 100\u2013500 M\u03a9 : ass\u00e9cher et retester<\/td>\n<\/tr>\n<tr>\n<td>Couleur du filtre \u00e0 gel de silice<\/td>\n<td>Bleu (sec)<\/td>\n<td>Partiellement rose<\/td>\n<td>Enti\u00e8rement rose\/rouge : r\u00e9g\u00e9n\u00e9rer ou remplacer<\/td>\n<\/tr>\n<tr>\n<td>TDCG (gaz combustibles totaux)<\/td>\n<td>&lt; 720 ppm<\/td>\n<td>720\u20131 920 ppm<\/td>\n<td>&gt; 1 920 ppm : enqu\u00eate d\u00e9taill\u00e9e selon IEEE C57.104<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Soyez conscient que les tendances sont plus importantes que les mesures uniques : une temp\u00e9rature d'huile de 78\u00b0C est plus alarmante si elle augmente de 5\u00b0C par semaine que si elle reste stable avec une charge constante.<\/p>\n<h2 id=\"troubleshooting\">D\u00e9pannage des d\u00e9fauts les plus courants<\/h2>\n<p>S'il y a des indications de dysfonctionnement, effectuez une enqu\u00eate ordonn\u00e9e au lieu de faire des suppositions. Lors du d\u00e9pannage des transformateurs, il peut \u00eatre utile de consulter le tableau suivant des probl\u00e8mes courants et des causes possibles, ainsi que les premiers tests que vous devriez effectuer :<\/p>\n<table>\n<thead>\n<tr>\n<th>Sympt\u00f4me<\/th>\n<th>Causes les plus probables<\/th>\n<th>Premi\u00e8res v\u00e9rifications<\/th>\n<th>Prochaine \u00e9tape si non r\u00e9solu<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Bruit inhabituel \/ changement de bourdonnement<\/td>\n<td>Serrage du noyau l\u00e2che, boulons de montage l\u00e2ches, vibration de l'entra\u00eenement OLTC, d\u00e9charge partielle, harmoniques de charge<\/td>\n<td>Tighten bolts, compare noise to load level, listen for crackling<\/td>\n<td>PD measurement, core ground current test<\/td>\n<\/tr>\n<tr>\n<td>Oil level falling<\/td>\n<td>Leak at gaskets\/bushings, breather fault, temperature drop<\/td>\n<td>Inspect all joints, check temperature correlation<\/td>\n<td>Find and fix leak; test oil for moisture<\/td>\n<\/tr>\n<tr>\n<td>Oil temperature high<\/td>\n<td>Overload, cooling fans not running, blocked radiators, low oil level, high ambient<\/td>\n<td>Check load vs rating, fan operation, radiator airflow<\/td>\n<td>Review loading guide, clean coolers, DGA<\/td>\n<\/tr>\n<tr>\n<td>Buchholz gas alarm<\/td>\n<td>Minor gas from normal aging, overheating, or an internal fault<\/td>\n<td>Collect gas sample, note quantity and odor<\/td>\n<td>DGA of gas and oil; compare with IEEE C57.104<\/td>\n<\/tr>\n<tr>\n<td>Buchholz trip (sudden)<\/td>\n<td>Major internal fault, arcing, short circuit<\/td>\n<td>Do NOT re-energize; isolate and inspect<\/td>\n<td>Full internal inspection, DGA, winding tests<\/td>\n<\/tr>\n<tr>\n<td>Low insulation resistance<\/td>\n<td>Moisture in oil, wet winding, dust and contamination<\/td>\n<td>Megger test, oil moisture test<\/td>\n<td>Dry-out process, oil filtration, retest<\/td>\n<\/tr>\n<tr>\n<td>Overheating at connections<\/td>\n<td>Loose terminals, corroded lugs, undersized conductors<\/td>\n<td>Thermography of terminals and busbars<\/td>\n<td>Re-torque to spec, replace lugs<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2 id=\"buchholz\">Buchholz Relay Operation: What It Tells You<\/h2>\n<p>The Buchholz relay is positioned in the pipe connecting the transformer tank to the conservator, being part of an internal fault detection system. The relay features two floats: the upper float sends an alarming signal upon gas accumulation and the lower float operates the circuit-breaker when oil suddenly moves to the conservator and a significant fault occurs.When the Buchholz device alarms:<\/p>\n<ul>\n<li>It is necessary to note the quantity of gas released and whether the relay just gave an alert signal or worked to shut down the electrical circuit.<\/li>\n<li>It is important to gather a gas sample from the Buchholz valve and note the amount of gas and its odor. An unpleasant smell can be an indicator of arcing.<\/li>\n<li>It is essential to analyze the gathered gas: abnormally high quantities of hydrogen and acetylene reveal the occurrence of arcing and serious faults, while a predominant air composition may show problems with the air breather.<\/li>\n<li>It is necessary to take the DGA oil sample at the same time and compare gas concentrations with the conditions described in IEEE C57.104 standard.<\/li>\n<li>It is necessary to make a decision: if the gas composition indicates overheat or arcing phenomena &#8211; do not reconnect the unit until internal inspection and possible repair works. If gas accumulation is not statistically important and does not indicate flawed operation, the unit may keep on working without any problems, but ongoing inspections should be done to be sure about the absence of faults.<\/li>\n<\/ul>\n<p>Gas accumulation event should be documented and reported to the engineer to allow further tracking of gas formation.<\/p>\n<h2 id=\"oil-leaks\">Oil Leakage: Causes and Handling<\/h2>\n<p>The most visible maintenance problem with regard to the oil leakage is oil leaks that are important for three reasons: lowering oil level (which affects the effectiveness of cooling and insulation systems), letting moisture and air in through the leaks, and causing environmental and safety problems. Oil leaks are most likely to occur at the gaskets at the connection between the tank and the cover, at the bushing bases, at the flanges of conservators&#8217; pipes, at the connections to the cooling radiator, and at the drain valve.<\/p>\n<p>When trying to find an oil leak, it is best to make some inspections with a clean cloth or, in the case of a very small leak, check the joints at night with a flashlight (there would be visible oil traces). It is recommended to tighten the bolts on the flange according to the manufacturer&#8217;s instructions and if it does not help, to replace the gaskets with the new materials. After any repair, the oil must be filled through the conservator from the same batch and after one week a sample must be checked for moisture. Even small oil leaks can lead to big problems as the unit leaking 5-10 liters a month will begin taking in moist air through the breather.<\/p>\n<h2 id=\"temperature\">Overheating and Cooling Faults<\/h2>\n<p>Continuous overheating is the quickest way to decrease the lifespan of a transformer owing to the fact that the aging of the insulation is practically doubled with every rise of 6-8 degrees K in temperature. In the case when the oil temperature is high, take the following steps:<\/p>\n<ul>\n<li>Check if the load corresponds to the nameplate and the loading pamphlet (IEC 60076-7). If the load exceeds the nameplate figure and there is no cooling from fans, it will lead to overheating.<\/li>\n<li>Check the state of fan and pump. In an ONAF transformer, fans work automatically by the thermostat; the failure of the fan or problems with circulation of air in the radiator may lead to a temperature increase of 10-20 deg.<\/li>\n<li>Inspect the radiator to make sure that the vanes are clean; use air or water but do not use a high-pressure washer as it might lead to damaging the radiator.<\/li>\n<li>Check the oil level and circulation. Low level of oil may lead to overheating because of poor cooling and hot points near the winding.<\/li>\n<li>Find out whether there are internal causes of the problem.<\/li>\n<\/ul>\n<h2 id=\"electrical\">Electrical Faults: Insulation Resistance and Grounding<\/h2>\n<p>Testing of insulation resistance (megger) is used for a typical evaluation of moisture and contamination. Each winding is tested both to ground and each other using a voltage of 500\u20135,000 V depending on the transformer. The temperature during the test should also be registered. The critical point is not the absolute measurement of insulation resistance, but its change over time, so to compare with the previous year results, more importance should be put to the developments in values rather than the final numbers. In case low insulation resistance is detected, testing of oil for moisture and dielectric strength follows. If the oil is found to be contaminated, filtering and\/or changing of it is the next step, followed by retesting. In the worst situations, drying out the transformer may be required, following provided recommendations on the controlled process of the drying procedure by manufacturers.<\/p>\n<p>Grounding is an independent and very important daily procedure. The tank should be grounded with all non-current-carrying metallic parts; the resistance of grounding is generally 1\u20135 \u03a9 depending on the system. If grounding fails, the tank remains energized in case of any internal failure of the transformer. Visual inspection must be performed regularly on the polymeric straps used for grounding to make a check on their corrosion, looseness and overall condition.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-10762\" src=\"https:\/\/subian-electric.com\/wp-content\/uploads\/2026\/08\/Building-a-Maintenance-Plan-and-Budget.webp\" alt=\"Building a Maintenance Plan and Budget\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2 id=\"maintenance-plan\">Building a Maintenance Plan and Budget<\/h2>\n<p>Develop written maintenance plans from your checklists, assigning roles and budgets to relevant employees.<\/p>\n<table>\n<thead>\n<tr>\n<th>Cost Item<\/th>\n<th>Typical Annual Cost (per unit)<\/th>\n<th>Remarques<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Daily inspections (labor)<\/td>\n<td>$300\u2013$1,500<\/td>\n<td>10 minutes\/day of technician time<\/td>\n<\/tr>\n<tr>\n<td>Oil sampling and lab tests (annual)<\/td>\n<td>$200\u2013$500 per DGA sample<\/td>\n<td>Plus $150\u2013$400 for oil quality package<\/td>\n<\/tr>\n<tr>\n<td>Routine maintenance (tightening, cleaning, breather care)<\/td>\n<td>$500\u2013$2,000<\/td>\n<td>Consumables and labor<\/td>\n<\/tr>\n<tr>\n<td>Emergency repair reserve<\/td>\n<td>$2,000\u2013$10,000 per unit budgeted<\/td>\n<td>Gasket kits, oil, seals, fans<\/td>\n<\/tr>\n<tr>\n<td>Major overhaul (every 5\u201310 years)<\/td>\n<td>$5,000\u2013$40,000<\/td>\n<td>OLTC inspection, oil filtration, gaskets<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The main principle of maintenance budgeting is that the maintenance budget should never be lower than the cost of the potential risks. An annual DGA sample for $300 is a good investment compared with a potential loss in transformer costs between $250,000 and $1,500,000.<\/p>\n<h2 id=\"faq\">Questions Fr\u00e9quemment Pos\u00e9es<\/h2>\n<h3>\u00c0 quelle fr\u00e9quence l'huile de transformateur doit-elle \u00eatre \u00e9chantillonn\u00e9e ?<\/h3>\n<p>For functioning transformers, taking a sample once per year is normal practice. In the case of distribution transformers, oil sampling should be performed once every one to three years depending on the level of importance of the transformer. For each alarm activated by the Buchholz relay, any overloading situation, any type of malfunction, or if there is a considerable gas production, a sample should be taken as soon as possible (in a few weeks). On average, the costs for one sample of the DGA are from $200 up to $500 together with a report from the laboratory.<\/p>\n<h3>What is the normal operating temperature of a transformer?<\/h3>\n<p>The temperature at the top of the oil in an active oil transformer has to be from 60\u00b0C up to 75\u00b0C in temperate climate conditions. If the temperature exceeds 85\u00b0C for a long time, it is necessary to check the situation. If the hot-spot temperature is over 98\u00b0C, the process of insulation aging is taking place.<\/p>\n<h3>What does a Buchholz relay alarm mean?<\/h3>\n<p>The gas accumulation in the conservator pipe is what triggers the Buchholz relay to alarm. The gas could be either air produced during the fault of the breather or gases produced during overheats and arcing inside the tank. Consequently, the gas needs to be sampled, and a DGA must be performed to make the conclusion.<\/p>\n<h3>How do I handle a transformer with low insulation resistance?<\/h3>\n<p>First of all, you have to check the oil, saturation, and dielectric strength of the oil. It is most likely that the oil is wet. The oil must be filtered or replaced in case saturation is more than 20-30 ppm.In the case when the winding of the transformer is wet, a procedure of controlled drying should be performed according to the instructions given by the manufacturer.<\/p>\n<h3>What should I do when a transformer trips on the Buchholz relay?<\/h3>\n<p>Before switching on the transformer, make sure to isolate the transformer unit and take gas and oil samples for the DGA. After the Buchholz relay has been tripped, it is essential to check the relay and the conservator.<\/p>\n<h2 id=\"references\">R\u00e9f\u00e9rences<\/h2>\n<ul>\n<li><a href=\"https:\/\/ieeexplore.ieee.org\/document\/9771388\" rel=\"nofollow noopener\" target=\"_blank\">IEEE C57.104: Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers<\/a> \u2014 The reference for DGA interpretation and alarm levels during troubleshooting.<\/li>\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/633\" rel=\"nofollow noopener\" target=\"_blank\">IEC 60422: Supervision and Maintenance Guidance for Mineral Insulating Oils<\/a> \u2014 Defines oil quality limits and maintenance practice.<\/li>\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/632\" rel=\"nofollow noopener\" target=\"_blank\">IEC 60076-7: Loading Guide for Oil-Immersed Power Transformers<\/a> \u2014 The reference for temperature limits and cyclic\/emergency loading.<\/li>\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/637\" rel=\"nofollow noopener\" target=\"_blank\">IEC 60156: Insulating Liquids \u2014 Determination of the Breakdown Voltage<\/a> \u2014 Test standard for oil dielectric strength used in routine maintenance.<\/li>\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/352\" rel=\"nofollow noopener\" target=\"_blank\">IEC 60599: Guide to the Interpretation of DGA in Mineral Oil-Impregnated Equipment<\/a> \u2014 International framework for gas interpretation.<\/li>\n<li><a href=\"https:\/\/www.cigre.org\/\" rel=\"nofollow noopener\" target=\"_blank\">CIGR\u00c9<\/a> \u2014 Publishes technical brochures on transformer maintenance, failure statistics, and condition assessment.<\/li>\n<li><a href=\"https:\/\/subian-electric.com\/fr\/\">Jiangsu Subian Electric Power<\/a> \u2014 IEC 60076-compliant transformer manufacturer providing maintenance documentation and technical support.<\/li>\n<\/ul>\n<h2 id=\"conclusion\">Conclusion<\/h2>\n<p>The daily upkeep of transformers is very easy, inexpensive, and one of the best value-oriented undertakings within any electrical asset program. A brief preliminary walk-through that takes five minutes, a monthly routine inspection, and an annual sample of DGA investigation will easily help one find critical defects leading to the unmanageable events and turn them into planned maintenance instead. Generally, whenever an abnormality arises, the algorithm of troubleshooting must be initiated for efficient problem exclusion: first, check the obvious variables, then collect the oil samples, and finally, interpret them according to standards and take action except having to wait until the protection activates itself.<\/p>\n<ul>\n<li>Implement the daily checklist and record the readings.<\/li>\n<li>Take oil samples for DGA at least once a year, and after the Buchholz event.<\/li>\n<li>Investigate the changes of temperature, noise and level instead of accepting them.<\/li>\n<li>Never reenergize after Buchholz happens without checks.<\/li>\n<li>Consider a price of $200\u2013$500 for one DGA sample compared to over $250,000 of replacing the electrical machine.<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>It&#8217;s Tuesday morning at 6:50 AM when the shift electrician at a medium-sized plant realizes that a 2,000 kVA transformer is buzzing much louder than it usually does. The Buchholz relay window has a tiny gas pocket, and the oil gauge on the conservator reads lower than last month. Everyone knows the saying that trouble [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":10760,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[77],"tags":[],"class_list":["post-10759","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"blocksy_meta":[],"acf":[],"_links":{"self":[{"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/posts\/10759","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/comments?post=10759"}],"version-history":[{"count":2,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/posts\/10759\/revisions"}],"predecessor-version":[{"id":10985,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/posts\/10759\/revisions\/10985"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/media\/10760"}],"wp:attachment":[{"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/media?parent=10759"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/categories?post=10759"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/subian-electric.com\/fr\/wp-json\/wp\/v2\/tags?post=10759"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}