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Share the equipment and project requirements. If you need help selecting a model, describe the application.
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Medium Voltage Components
Outdoor vacuum circuit breakers, disconnectors and current and voltage transformers for protection, isolation and measurement. Share your electrical ratings, installation conditions and drawings for a configuration review.
Explore Medium Voltage Components
Start with the circuit function. Review each device’s ratings, installation arrangement and connections within its product family.
Outdoor Vacuum Circuit Breakers
Outdoor switching and fault interruption. Compare the ZW32-12, ZW32-24 and ZW7-40.5 series for the specified duty.
Disconnectors
Isolation points for indoor and outdoor installations. Review the mounting, operating sequence and earthing requirements.
Instrument Transformers
CT and VT signals for metering and protection. Specify ratio, accuracy, burden and secondary connections.
Component Types and Functions
Match each circuit function
- Interrupt currentCircuit breaker
Switching and fault-clearing duty
- Provide isolationDisconnector
An isolation point in the operating scheme
- Provide signalsCT or VT
Current or voltage inputs to meters and protection
Mark each device’s location and function on the single-line diagram, including its connections to the protection and metering circuits.
Circuit breaking and protection
- Use
- Switch the circuit and interrupt fault current within the specified device ratings.
- Review
- Voltage and current duty
- Fault level and duration
- Operating sequence
- Control and protection interfaces
- Coordination
- Specify the protection relay, controller and any automatic reclosing functions required with the breaker.
Isolation and operating sequence
- Use
- Provide an isolation point with the required mounting and operating arrangement.
- Review
- Indoor or outdoor location
- Current and withstand duty
- Operation and interlocks
- Earthing and connection points
- Coordination
- Isolation does not replace load or fault interruption. Define the associated switching device and operating sequence.
Current and voltage measurement
- Use
- Provide current or voltage signals for the specified metering and protection circuits.
- Review
- CT or VT ratio
- Accuracy and burden
- Measurement or protection duty
- Secondary connections
- Coordination
- CTs and VTs have different primary connections and selection requirements. Confirm each device separately.
For a complete assembly, review the component requirements together with the panel arrangement, protection scheme and equipment supplied by others.
Explore MV & LV SwitchgearExplore Prefabricated SubstationsComponent Configuration Guide
Component Applications
Utility and secondary distribution
Review overhead-feeder switching, fault interruption and isolation points against the utility scheme. Specify mounting, control supply, protection connections and outdoor conditions for each device.
Explore applicationIndustrial incoming supply
Coordinate incoming protection, isolation and metering with the plant single-line diagram. Match the selected devices to the installation space, approved control scheme and maintenance arrangements.
Explore applicationInfrastructure metering and protection
Define the current and voltage inputs required by meters and protection relays. Review CT/VT ratios, accuracy, burden, secondary wiring and indoor installation interfaces together.
Explore applicationRenewable plant connection
Start with the plant connection requirements and AC collection scheme. Confirm switching duty, isolation responsibilities, protection signals and the environmental conditions at each installation point.
Explore applicationComponent Quotation Checklist
Equipment & supply scope
- Device list
- Required equipment families, quantities, circuit functions and any specified models or accessories.
- Connection points
- Primary terminals, control circuits and CT/VT secondary connections identified on the project diagrams.
Ratings & interface drawings
- Electrical requirements
- System ratings, switching or withstand duties, control supply and the CT/VT ratio, burden and accuracy schedule.
- Installation details
- Mounting dimensions, terminal orientation, connection clearances, operating access and site conditions.
Inspection & acceptance
- Acceptance plan
- Applicable standards, inspection points, document schedule and project acceptance criteria.
- Test documents
- Agree test documents for the specified device and rating combination, together with the records required for the supplied equipment.
Packing & handover
- Transport arrangement
- Package dimensions, weight, handling points and separately packed mechanisms or accessories.
- Dispatch documents
- Approved drawings, operating instructions, packing lists and agreed inspection records.
Why Choose SUBIA for MV Components
Application and equipment review
SUBIA reviews your circuit function, ratings and installation conditions to prepare the proposed equipment configuration.
Interface coordination
Discuss mounting, primary connections, control supply and secondary terminals alongside the equipment and systems supplied by others.
Drawings and inspection documents
Agree the drawing schedule and inspection records during technical review, matching the documents to the devices and ratings being supplied.
Packing and delivery coordination
Review package markings, accessory lists and handling requirements so your team can plan receipt, storage and installation at the site.
Component Selection & Procurement FAQs
How do I choose between a circuit breaker, disconnector and instrument transformer?
Start with the circuit function. A circuit breaker provides the specified switching and fault-interruption duty; a disconnector provides an isolation point; a CT or VT supplies current or voltage signals for metering and protection. Use the single-line diagram to identify each device and its connections.
Can a disconnector interrupt load or fault current?
Do not assume a disconnector has load-break or circuit-breaker capability. Its isolation function must be coordinated with the appropriate switching device and operating sequence. Review any stated switching duty against the exact device specification before use.
Which ratings are needed for an outdoor vacuum circuit breaker?
Provide the system voltage, rated current, prospective fault current and required fault-duty values, frequency and operating sequence. Include control supply, protection connections, mounting and site conditions. Confirm the complete rating combination for the proposed model.
What information is needed for a CT or VT enquiry?
Identify CT or VT, the required ratio, secondary values, accuracy class, burden and metering or protection purpose. Include the wiring arrangement, terminal requirements, insulation level and available mounting space. Review current-transformer and voltage-transformer requirements separately.
How do indoor and outdoor conditions affect selection?
State the installation location, ambient temperature, altitude, exposure and any contamination or condensation concerns. Provide mounting dimensions, connection details and operating access. Indoor devices require an installation arrangement suited to their specified service conditions.
What should I prepare for a quotation?
Send the equipment list, quantities, single-line diagram, known electrical ratings and installation drawings. Add control or secondary-circuit requirements and identify items still to be confirmed. Agree the required drawings, inspection records, acceptance points and delivery documents during review.
