Instrument Transformer Landing Page
Current Transformer Overview
Use this current transformer overview to prepare CT ratio, accuracy class, burden and switchgear installation requirements before RFQ.
Product Type
Current Transformer
Rated Current Ratio
Primary current by feeder design, secondary 1A or 5A
Installation
Indoor switchgear, panel or project-defined mounting
Standard
IEC 61869 series or tender-specified standard
Product Overview
Engineering Selection Context
Current Transformer Overview is specified for metering, protection and signal conversion in medium-voltage or low-voltage electrical systems.
The model name is only one part of the RFQ. Buyers should also define ratio, burden, accuracy class, insulation level, installation position, terminal arrangement and panel type.
Ziyao Power can support instrument transformer selection for KYN28, ring main unit, LV switchgear and project-specific metering or protection circuits.
Technical Specifications
Key Data Required Before Quotation
These values should be confirmed against the single-line diagram, tender document and site conditions.
| Rated Current | Primary current by feeder design, secondary 1A or 5A |
|---|---|
| Frequency | 50Hz or 60Hz |
| Typical MV CT Family | LZZBJ9-10/12 epoxy cast-resin post current transformer |
| Documented Primary Current Range | 5A to 3000A for LZZBJ9-10/12 typical selection range |
| Documented Accuracy Combination | 0.2S / 0.5 / 10P for metering and protection cores |
| CT Safety Rule | CT secondary circuit must not be open-circuited during operation |
| Accuracy Class | 0.2, 0.5, 5P, 10P or project-defined |
| Burden | Specified in VA according to relay, meter and cable load |
| Standard | IEC 61869 instrument transformer standard series; IEC 60044-1 / GB legacy references can be checked when tender requires them |
| Application | Metering, protection, feeder measurement and switchgear integration |
| Protection Level | Indoor epoxy resin insulation or cabinet-integrated protection by design |
| Installation Type | Indoor switchgear compartment, busbar, cable side or panel mounting |
| Model Focus | Overview for metering CT and protection CT selection |
Construction & Materials
Build Details Buyers Should Confirm
Material decisions influence loss level, thermal behavior, footprint, maintenance and approval documents.
Epoxy resin insulation for indoor switchgear environments.
Precision magnetic core and winding design selected for metering or protection accuracy.
Clear secondary terminal marking for field wiring and commissioning.
Compact mounting geometry coordinated with switchgear compartment space.
Applications
Where This Page Fits
KYN28 and other medium-voltage switchgear metering and protection circuits.
Low-voltage switchgear feeders, capacitor panels and distribution boards where applicable.
Utility, industrial, commercial and renewable power distribution projects.
Retrofit projects where existing panel dimensions and wiring must be checked before order.
Standards & Compliance
Documents for Engineering Review
IEC 61869 instrument transformer series.
Routine electrical test and inspection before shipment.
Project drawings and terminal diagrams can be provided for engineering approval.
Accuracy class and burden must match the connected meter or relay loop.
FAQ
Procurement Questions
What information is required for Current Transformer Overview quotation?
Provide current ratio, frequency, accuracy class, burden, insulation level, installation position, panel type, quantity and destination country.
How should accuracy class be selected?
Metering circuits usually require measuring accuracy, while protection circuits require protection class. The relay or meter datasheet should be checked before final selection.
Why does burden matter?
Burden represents the load connected to the secondary circuit. If it is not correctly specified, the transformer may fail to meet the required accuracy in actual service.
Can the unit be installed in existing switchgear?
Yes, but panel dimensions, busbar position, mounting holes and terminal access should be checked before quotation.
Is epoxy resin insulation suitable for indoor switchgear?
Yes. Epoxy resin insulation is widely used for indoor instrument transformers in medium-voltage switchgear.
Can secondary terminals be customized?
Terminal arrangement and marking can be reviewed according to the wiring diagram and panel layout.
What standards are normally referenced?
IEC 61869 series is commonly referenced for instrument transformers. Local grid or tender standards can also be reviewed.
Can Ziyao Power supply CT/VT with switchgear?
Yes. Instrument transformers can be supplied as separate components or coordinated with switchgear and distribution packages.
How should the CT primary current be selected?
Use the maximum feeder load current as the base and typically select around 1.2 to 1.5 times that value, then verify thermal withstand against the installation short-circuit level.
Why must a CT secondary not be open-circuited?
With the secondary open, the CT can generate dangerous high voltage on the secondary side because primary current continues to drive the magnetic core.
RFQ CTA
Send your specification for engineering review
Attach a transformer schedule, single-line diagram, switchgear drawing or load list. Our team will match the product configuration to voltage, capacity, installation and approval requirements.
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