Current Transformer Ratio Selection: Primary Current and Secondary Output

This guide explains the evidence chain for a current-transformer ratio. It does not calculate a project ratio, declare compatibility with a meter or protection relay, or provide secondary wiring or safety instructions.

Sekilas tentang Masukan Pengambilan Keputusan

Kolom ulasan	Pembeli harus menentukan	Bukti yang perlu diminta
Primary current	Normal, maximum and relevant operating range	Project load study
Output sekunder	Exact input required by the receiving meter or relay	Receiving-device manual
Rasio	Declared primary-to-secondary relationship	Exact CT model row
Measurement performance	Accuracy and burden under documented conditions	Manufacturer data and system calculation
Kesesuaian mekanis	Window, conductor, mounting and installation constraints	Drawing and installation review

Start With the Real Primary Current Range

The primary side should be described by the expected operating current, maximum normal condition and any meaningful variation that affects measurement. Selecting from conductor ampacity or protective-device frame size alone can place normal readings in an unsuitable part of the measurement range.

Record how the current estimate was obtained and whether future operating modes change it. The buyer does not need to force a final ratio before the receiving-device input and measurement objective are known.

Match the Secondary Output to the Receiving Device

A current transformer and a meter form an interface. The CT secondary declaration must match the exact input expected by the meter, transducer or relay. A familiar ratio notation is not enough to establish that relationship. Request both documents and review them together.

Do not use a product family page to infer input compatibility. Neighboring meter variants may accept different sensors or secondary signals. The approval record must name the exact receiving device and its terminal documentation.

Understand What the Ratio Expresses

The ratio states the declared relationship between primary current and secondary output under the product's defined conditions. It does not by itself establish accuracy across the required operating range, available burden, saturation behavior or suitability for protection. Those are separate evidence fields.

When quotations offer different ratios, compare the resulting measurement use rather than treating the values as catalog alternatives. Each proposal should explain how the ratio aligns with the project's primary-current range and receiving input.

Review Burden and Accuracy as a System

The connected input, lead path and terminals contribute to the secondary circuit seen by the transformer. The responsible engineer should calculate and verify that complete circuit against the exact CT and receiving-device documents. Procurement should preserve the inputs rather than guessing from a headline accuracy class.

Ask where accuracy is declared, at which conditions and for which order code. Never combine the ratio of one model, burden data from another and dimensions from a third. If the system calculation is missing, mark the proposal incomplete.

Confirm Frequency, Purpose and Operating Context

State whether the measurement supports indication, energy monitoring, control, protection or another purpose. These uses can demand different evidence. Also record the system frequency and waveform context that the manufacturer requires for its declaration.

This guide deliberately avoids treating a measurement CT as a protection CT or vice versa. The proposed device must be documented for the intended role, and any special behavior must be evaluated by the system designer.

Verify Window Size and Installation Constraints

The primary conductor, bar arrangement, insulation, bending space and access determine whether the CT can be installed. A ratio match does not prove mechanical fit. Request the exact outline drawing and confirm that the window accommodates the real conductor without unsupported modification.

For retrofit work, a split-core construction may change installation access, but it does not remove the need to review ratio, output, burden, accuracy and environmental conditions. Keep construction choice separate from electrical approval.

Membuat Berkas Bukti Model yang Tepat

Create one approval record for the proposed Current Transformer order code. Put each project requirement beside the supplier document that answers it. Preserve the exact datasheet, drawing, table, instruction or selection output used, including its revision or retrieval date. A category page can establish family context, but it cannot prove an exact rating, terminal arrangement or system combination.

Pastikan setiap pernyataan yang disetujui menggambarkan barang yang sama yang dapat dipesan. Casing yang serupa dapat berisi rangkaian, catu daya, terminal, aksesori, atau fungsi yang berbeda. Jangan menggabungkan batas maksimum keluarga dari satu varian, diagram dari varian lain, dan fitur opsional dari varian ketiga. Tandai kolom yang belum diselesaikan secara eksplisit agar tetap terlihat dalam tinjauan komersial.

Pisahkan Masukan Proyek dari Bukti Produk

The project team defines the application: source, load, duty, environment, controls, mechanical limits and required functions. The supplier identifies an exact Current Transformer and supports it with exact documents. Neither side should fill a gap by inference from appearance, a shared family name or one matching headline value.

Bekukan catatan permohonan selama proses perbandingan penawaran berlangsung. Jika terjadi perubahan pada topologi, sumber, beban, lingkungan, wadah, atau output yang dibutuhkan, terbitkan catatan yang telah direvisi dan mintalah setiap pemasok untuk mengonfirmasi kembali kandidat tersebut. Jika tidak, penawaran yang sekilas tampak sebanding mungkin sebenarnya memenuhi persyaratan teknis yang berbeda.

Kesalahan Umum dalam Pengadaan

Avoid selecting a Current Transformer from one headline value while the application context remains incomplete. Do not use a circuit, curve, terminal drawing or performance claim from a neighboring model. A product photograph and a family page can support discovery, but neither is exact technical evidence.

Hindari juga berasumsi bahwa suatu aksesori, fungsi komunikasi, peran perlindungan, atau hasil yang terkoordinasi sudah termasuk, kecuali jika hal tersebut tercantum dalam penawaran harga dan dokumen spesifikasi model yang tepat. Komponen pengganti harus memiliki topologi, nilai nominal, cara pemasangan, serta tinjauan bukti yang sama dengan kandidat asli.

Cara Membandingkan Penawaran Pemasok

Normalize every Current Transformer offer to the same application record. Keep document revisions, stated conditions, included accessories and open questions beside each value. This makes differences in delivered scope visible and prevents a lower-cost but narrower offer from appearing equivalent to a complete solution.

Hentikan perbandingan jika input aplikasi yang krusial tidak diketahui, model yang disebutkan tidak jelas, klaim yang diperlukan hanya didukung oleh produsen lain atau kode pesanan, atau pemasangannya berada di luar cakupan bukti yang tersedia. Hal-hal ini merupakan celah teknis, bukan detail redaksional.

Pengendalian Revisi dan Penggantian

Give the approved Current Transformer record a revision identifier and keep it with the project file. If the supplier changes the order code, accessory, firmware, drawing or stated operating condition, identify the change before accepting it. A substitution is a new technical proposal even when its price, housing or product-family name looks familiar.

Ulangi hanya pemeriksaan yang terpengaruh, tetapi jangan abaikan pemeriksaan tersebut. Pastikan bahwa kandidat yang telah direvisi tetap sesuai dengan aplikasi yang telah dibekukan, bahwa setiap dokumen yang dirujuk merupakan bagian darinya, dan bahwa semua pengecualian yang masih terbuka telah memiliki penanggung jawab. Langkah pengendalian perubahan kecil ini mencegah agar pilihan yang telah ditinjau secara teknis tidak digantikan oleh alternatif komersial yang belum ditinjau.

Alur Kerja Pengambilan Keputusan

• Bekukan catatan aplikasi dan sistem sebelum memilih kode katalog.
• Identifikasi fungsi yang tepat dan setiap antarmuka yang memerlukan bukti.
• Mohon kirimkan satu kode pesanan lengkap beserta lembar data dan gambar teknisnya yang terbaru.
• Hubungkan setiap persyaratan proyek dengan pernyataan produsen tertentu.
• Catat penyimpangan, perlengkapan tambahan, revisi dokumen, dan pertanyaan yang belum terjawab.
• Ulangi proses peninjauan setiap kali aplikasi atau produk yang diusulkan mengalami perubahan.

Use this workflow as a procurement and evidence discipline. It does not replace qualified design, installation instructions or the responsible engineer's approval for the Current Transformer application.

Daftar Periksa Persiapan RFQ

A practical current transformer ratio selection should be concise enough for a supplier to answer and complete enough to prevent silent assumptions. Identify unknown values as questions rather than allowing them to become undocumented selections.

• Primary current: Normal, maximum and relevant operating range.
• Secondary output: Exact input required by the receiving meter or relay.
• Ratio: Declared primary-to-secondary relationship.
• Measurement performance: Accuracy and burden under documented conditions.
• Mechanical fit: Window, conductor, mounting and installation constraints.
• Kode produk yang tepat, aksesori yang disertakan, dan revisi dokumentasi
• Jumlah, tujuan, persetujuan yang diperlukan, dan cakupan komersial

Mintalah penjelasan rinci mengenai ruang lingkup klaim klasifikasi, kompatibilitas, koordinasi, atau kinerja apa pun. Catat jumlah dan tujuan pengiriman setelah masukan teknis agar ketentuan komersial tidak mengaburkan pertanyaan-pertanyaan teknis yang belum terselesaikan.

Pertanyaan yang Sering Diajukan

Can CT ratio be selected from breaker size alone?

No. Use the real current range, receiving-device input and measurement objective.

Does a matching secondary value prove compatibility?

No. Burden, accuracy, frequency, terminals and the exact interface still require review.

Can a current transformer secondary be treated as an ordinary signal?

No. Follow qualified design practices and the exact manufacturer safety instructions.

Produk dan Panduan RITOKS yang Terkait

Tautan-tautan ini hanya memberikan konteks mengenai kelompok produk. Tautan kontekstual ini tidak menyatakan adanya kesalinggantungan, kompatibilitas, atau kombinasi sistem yang telah disetujui.

Current Transformer product category

BH-0.66-60I current transformer family

Trafo arus inti terbelah seri DP

GTA20L precision current transformer

Referensi Teknis

Sumber-sumber dari produsen ini hanya mendukung konsep-konsep teknik umum yang dijelaskan di bawah ini. Spesifikasi produk, diagram rangkaian, sertifikasi, dan hasil koordinasi mereka tidak berlaku untuk produk-produk RITOKS.

Schneider Electric, Pengukur Daya Multifungsi PowerLogic

Supports treating the meter input and measurement architecture as part of the complete system record. Schneider meter inputs do not establish compatibility with RITOKS CTs.

Ajukan Permohonan Peninjauan Model yang Tepat

Kirimkan persyaratan permohonan, pertanyaan mengenai dokumen yang tepat, jumlah, dan tujuan melalui formulir kontak RITOKS. Permohonan Penawaran (RFQ) memerlukan peninjauan model yang tepat; panduan ini tidak menyetujui penggantian sirkuit, instalasi, atau penggantian otomatis.

Hubungi RITOKS