{"id":2252,"date":"2026-10-06T06:17:53","date_gmt":"2026-10-06T06:17:53","guid":{"rendered":"http:\/\/ritoks.com\/"},"modified":"2026-10-06T06:17:53","modified_gmt":"2026-10-06T06:17:53","slug":"current-transformer-accuracy-class-burden","status":"publish","type":"post","link":"https:\/\/ritoks.com\/cs\/current-transformer-accuracy-class-burden\/","title":{"rendered":"Current Transformer Accuracy Class and Burden: Verification Guide"},"content":{"rendered":"

Current transformer accuracy class and burden describe a measurement system, not a standalone quality score. A CT specified for a particular class is assessed under defined conditions. The connected meter, cable and terminals impose a real secondary burden that must fit the evidence for the exact CT.<\/p>\n\n\n\n

This guide explains the questions a buyer should put in the technical file. It does not assign universal accuracy to a CT family or prescribe a ratio from the equipment name alone.<\/p>\n\n\n\n

P\u0159ehled podklad\u016f pro rozhodnut\u00ed<\/h2>\n\n\n\n
Oblast p\u0159ezkumu<\/th>Co zaznamen\u00e1v\u00e1 kupuj\u00edc\u00ed<\/th>D\u016fkazy, o kter\u00e9 je t\u0159eba po\u017e\u00e1dat<\/th><\/tr><\/thead>
Primary side<\/td>Expected current range and conductor arrangement<\/td>Load record and installation drawing<\/td><\/tr>
Secondary side<\/td>Output expected by receiving device<\/td>CT and meter input documents<\/td><\/tr>
Z\u00e1t\u011b\u017e<\/td>Meter input plus lead and connection contribution<\/td>Circuit estimate and exact CT data<\/td><\/tr>
P\u0159esnost<\/td>Required class under relevant conditions<\/td>Exact CT datasheet and test basis<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\"Current
Map the project inputs for current transformers before screening candidates.<\/figcaption><\/figure>\n\n\n\n

Define the measurement purpose<\/h2>\n\n\n\n

A monitoring display, energy accounting function and control input may demand different evidence. State what the reading will be used for, its relevant operating range and the consequences of error. The CT ratio and class should follow that purpose.<\/p>\n\n\n\n

If the circuit rarely operates near its nominal maximum, consider performance over the actual range rather than selecting from one full-scale number. Ask the supplier for the exact conditions to which its accuracy statement applies.<\/p>\n\n\n\n

Understand class as a conditional statement<\/h2>\n\n\n\n

An accuracy class describes performance under a defined standard or test basis. It is not a promise that the installed meter will show that error under every current, frequency, temperature or burden.<\/p>\n\n\n\n

Read the complete CT datasheet, including the specified output, rated burden and class conditions. Do not transfer a class label from one variant, core size or ratio to another.<\/p>\n\n\n\n

Calculate the complete secondary burden<\/h2>\n\n\n\n

The receiving meter input is only part of the load seen by the CT secondary. Lead resistance, terminals and other connected devices can contribute. Longer runs and multiple instruments may materially change the burden.<\/p>\n\n\n\n

Document the secondary route and the actual devices attached to it. Compare the resulting burden with the exact CT evidence; if the circuit changes, update the assessment. Avoid treating a catalog burden value as a measurement of the installed circuit.<\/p>\n\n\n\n

Match ratio and output to the meter<\/h2>\n\n\n\n

The CT primary ratio should represent the expected current range, while the secondary output must match the meter input. A number in the product title does not prove the output of every order code or compatibility with every panel meter.<\/p>\n\n\n\n

Obtain both connection diagrams and the meter configuration method. Record any programmable ratio in the commissioning file so the display and exported data use the same scaling.<\/p>\n\n\n\n

Check physical installation<\/h2>\n\n\n\n

Solid-core and split-core devices may solve different installation constraints. Confirm conductor or busbar dimensions, window space, mounting access and orientation. The choice of housing also affects how the secondary circuit can be routed and inspected.<\/p>\n\n\n\n

If retrofitting a live panel is proposed, the work method needs a separate safety review by qualified personnel. Do not infer installation permission from the split-core label.<\/p>\n\n\n\n

Verify the system, not only the CT<\/h2>\n\n\n\n

A CT, meter, wiring path and configured ratio form one measurement chain. Commissioning should check polarity or direction where relevant, expected response and scaling under known conditions.<\/p>\n\n\n\n

Keep the as-built secondary diagram and configuration alongside the selected CT order code. This makes it possible to diagnose a discrepancy between the meter display and another measurement without guessing which component changed.<\/p>\n\n\n\n

Request evidence that matches the quoted item<\/h2>\n\n\n\n

Ask for exact ratio, output, rated burden, accuracy basis, physical drawing and installation instructions for the proposed CT. Separate what the product page shows from what the order-specific documents prove.<\/p>\n\n\n\n

A proposal remains open if the accuracy class is visible but the burden or operating conditions are not. Resolve those fields before approval, especially when the reading supports a commercial or control decision.<\/p>\n\n\n\n

Vytvo\u0159te soubor d\u016fkaz\u016f pro p\u0159esn\u00fd model<\/h2>\n\n\n\n

A category or product-family page helps locate relevant options; it does not by itself approve one variant. For current transformers, keep the full proposed order code, current datasheet, terminal or mounting drawing, operating instructions and any project calculation together. Read the conditions attached to each rating or function. If the evidence belongs to a neighboring model, request the correct document instead of carrying the claim across.<\/p>\n\n\n\n

Projektov\u00fd t\u00fdm odpov\u00edd\u00e1 za vstupn\u00ed \u00fadaje syst\u00e9mu a krit\u00e9ria p\u0159ej\u00edmky. Dodavatel odpov\u00edd\u00e1 za podklady k nab\u00edzen\u00e9 polo\u017ece. P\u0159i technick\u00e9m posouzen\u00ed p\u0159i\u0159a\u010fte ka\u017ed\u00fd povinn\u00fd po\u017eadavek k p\u0159esn\u011b tomu dokumentu a revizi, kter\u00e9 jej spl\u0148uj\u00ed. Chyb\u011bj\u00edc\u00ed pole ozna\u010dte jako otev\u0159en\u00e9, podm\u00edn\u011bn\u00e9 nebo nepodporovan\u00e9. T\u00edm vznikne sledovateln\u00e9 rozhodnut\u00ed a zabr\u00e1n\u00ed se tomu, aby p\u0159\u00edzniv\u00e1 celkov\u00e1 hodnota zakryla nekompatibiln\u00ed propojen\u00ed nebo instala\u010dn\u00ed podm\u00ednku.<\/p>\n\n\n\n

Porovnejte kompletn\u00ed nab\u00eddky<\/h2>\n\n\n\n
Polo\u017eka<\/th>Z\u00e1znam v porovn\u00e1n\u00ed<\/th>D\u016fvod<\/th><\/tr><\/thead>
Polo\u017eka k objedn\u00e1n\u00ed<\/td>\u00dapln\u00fd k\u00f3d, varianty a p\u0159ilo\u017een\u00e9 p\u0159\u00edslu\u0161enstv\u00ed<\/td>Zabra\u0148uje vytv\u00e1\u0159en\u00ed p\u0159edpoklad\u016f na \u00farovni rodiny<\/td><\/tr>
Shoda \u017e\u00e1dost\u00ed<\/td>P\u00edsemn\u00e1 odpov\u011b\u010f na ka\u017ed\u00fd podn\u011bt k projektu<\/td>Zajist\u00ed, aby v\u00fdjimky z\u016fstaly viditeln\u00e9<\/td><\/tr>
Dokumentace<\/td>Technick\u00fd list, v\u00fdkres, n\u00e1vod a revize<\/td>Odkazy na n\u00e1roky k nab\u00edzen\u00e9 polo\u017ece<\/td><\/tr>
Otev\u0159en\u00e9 body<\/td>Vlastn\u00edk a term\u00edn pro vyjasn\u011bn\u00ed<\/td>Zabra\u0148uje ml\u010denliv\u00e9mu souhlasu<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\"Current
Compare current transformers offers using exact-model evidence and open questions.<\/figcaption><\/figure>\n\n\n\n

Pro ka\u017edou cenovou nab\u00eddku pou\u017eijte stejn\u00fd zad\u00e1vac\u00ed list. Obchodn\u00ed podm\u00ednky, jako jsou cena a dodac\u00ed lh\u016fta, lze porovnat a\u017e po sjednocen\u00ed technick\u00e9ho rozsahu. Nevypln\u011bn\u00e9 dopl\u0148ky, nepodlo\u017een\u00e9 parametry nebo nevyjasn\u011bn\u00e9 p\u0159edpoklady ohledn\u011b zapojen\u00ed nepova\u017eujte za ekvivalent zdokumentovan\u00e9 nab\u00eddky. Pokud je navr\u017eena alternativa, zeptejte se, kter\u00e9 vstupn\u00ed \u00fadaje se m\u011bn\u00ed, a opakujte p\u0159\u00edslu\u0161nou kontrolu.<\/p>\n\n\n\n

Kontrola instalace a p\u0159evzet\u00ed<\/h2>\n\n\n\n

P\u0159ed instalac\u00ed se ujist\u011bte, \u017ee dodan\u00fd \u0161t\u00edtek, kompletn\u00ed k\u00f3d a p\u0159\u00edslu\u0161enstv\u00ed odpov\u00eddaj\u00ed schv\u00e1len\u00e9mu z\u00e1znamu. Porovnejte svorky, zp\u016fsob upevn\u011bn\u00ed, p\u0159\u00edstup k vodi\u010d\u016fm a ve\u0161ker\u00e9 uveden\u00e9 orientace s p\u0159esn\u00fdmi pokyny. V\u00fdrobek, kter\u00fd se fyzicky jev\u00ed jako podobn\u00fd schv\u00e1len\u00e9 verzi, m\u016f\u017ee m\u00edt p\u0159esto odli\u0161nou elektrickou konfiguraci, mo\u017enost ovl\u00e1d\u00e1n\u00ed nebo zku\u0161ebn\u00ed podm\u00ednky.<\/p>\n\n\n\n

Plan an as-built check that addresses the project’s real risks. This may involve wiring against the approved diagram, functional response, measurements under representative operating states and confirmation of any communication or alarm feature. Record the conditions and results. The acceptance plan should come from the application and supplier evidence, not from a generic article checklist.<\/p>\n\n\n\n

Kontroln\u00ed seznam pro \u017e\u00e1dost o cenovou nab\u00eddku<\/h2>\n\n\n\n