CBCTs OF ALL DIA FROM 30MM TO 600MM (SQUARE And RECTANGULER)

Core Balance / Residual Current Transformer (CBCT / RCCT)

The Core Balance (Residual) Current Transformer is designed for accurate detection of residual current and earth leakage, providing reliable protection for electrical systems. It is widely used with earth fault relays in distribution panels, MCCs, switchboards, and protection panels.

These CTs are suitable for detecting residual currents in the range of 30 mA to 3000 mA, ensuring dependable earth fault protection in industrial and commercial installations.

Key Features

Accurate residual current / earth leakage detection

Sensitivity range: 30 mA to 3000 mA

Suitable for protection, metering, and monitoring applications

Compatible with earth fault and protection relays

Stable performance under industrial operating conditions

Construction & Design

Core Type: Toroidal / Rectangular core

Construction: Solid or split core (as per requirement)

Core Material: Low-loss grain-oriented silicon steel or equivalent magnetic material

Winding: Enamelled copper secondary winding with proper insulation

Encapsulation: Resin-filled or epoxy-moulded housing for mechanical strength and moisture protection

Window Size Options

Available in standard window sizes:

30, 50, 70, 100, 150, 200, 250, 300, 400 & 600 mm

(Custom window sizes available on request)

Standards & Compliance

Manufactured in compliance with applicable standards, including:

IEC 61869 (CT performance & testing)

IEC 60044 / IEC 60044-8 (Residual Current Transformers)

Relevant IS standards and safety regulations

Applications

Earth leakage and ground fault protection

Distribution panels and MCC panels

Switchgear and control panels

Energy monitoring and protection systems

Customization & Supply

Custom sensitivity and window sizes available

Suitable for indoor industrial applications

Tested for quality and reliability before dispatch

Window Sizes (Mechanical)

The transformer shall be supplied in the following standard window sizes (nominal internal opening). Customer may specify rectangular window instead of circular where required.

Note: Window dimension equals internal window diameter for circular cores, or internal width/height for rectangular cores as specified on order.

Accuracy & Performance

• Accuracy class (protection):Typically Class 1.0 or 0.5 (selectable), or as required by relay/manufacturer. For residual CTs used for protection, the accuracy shall meet the protection class selected across the specified operating range.
• Phase error & ratio error: Shall comply with selected accuracy class across the rated burden.
• Lowest magnetizing current & residual flux: Designed for low magnetizing current to ensure reliable measurement at low primary (mA) levels.
• Rated burden: Typical provision 1 VA to 10 VA depending on secondary rating and customer requirement. Specify burden when ordering.

Mechanical & Environmental

• Degree of protection: IP20 (indoor) standard. Higher IP rating (IP54 / IP65) available on request for specific housings.
• Operating temperature: -10 C to +55 C (standard). Extended temperature ranges available on request.
• Storage temperature: -20 C to +70 C.
• Humidity: Up to 95% RH non-condensing.
• Vibration / Shock: Designed to meet normal industrial environment conditions; details on request.

Terminals & Connections

• Secondary terminals: Clearly marked S1, S2 or Sec +, Sec -. Connections shall be screw type terminals or flying leads as specified.
• Earthing: Core/body earth provision where applicable marking and earthing point provided.
• Polarities / direction: Marked on housing. For split-core units, clear open/close direction marking.

Mounting

• Mounting options: Clamp-on / panel mount / DIN-rail mount / bolt-on mounting feet as per model and customer requirement.
• Fixing hardware: Supplied with each unit, unless otherwise specified.

Tests

Routine Tests (each unit)

• Visual & dimensional inspection.
• Insulation resistance test.
• Ratio test at specified primary current.
• Polarity check.
• Dielectric (voltage) test as per applicable standard.
• Winding continuity and resistance check.

Type Tests (manufacturers lab)

• Temperature rise test.
• Impulse voltage test (if specified to standard levels).
• Accuracy and burden tests over specified ranges.
• Vibration / mechanical tests (if specified).

Acceptance Criteria

• Test certificates to be supplied for routine tests for each lot. Type test certificates to be supplied once per design or upon significant change.

Marking & Documentation

Each unit shall be permanently marked with:

• Manufacturer name / trade mark
• Type / model
• Serial number
• Window size
• Rated primary sensitivity (mA)
• Secondary rating (1 A / 5 A)
• Frequency and accuracy class
• Year of manufacture

Documentation to be supplied with each delivery:

• Packing list
• Routine test certificates
• Installation and instruction manual
• Dimensional drawings and wiring diagram

Packing & Delivery

• Suitable packing for sea/road transport, protecting the product from mechanical damage and moisture.
• Units to be supplied in cartons with cushioning.

Options (to be specified in PO)

• Split-core construction for retro-fit installation
• Secondary termination type (terminal block / flying leads)
• Secondary rated current (1 A or 5 A)
• Accuracy class and rated burden
• Special IP rating or conformal coating for hostile environment
• Mounting accessories (DIN rail, clamps, brackets)

Example Ordering Information

Example 1: CB-100 -100 mm window, primary sensitivity 30 mA, secondary 1 A, split-core, DIN-rail mount, IP20.

Example 2: CB-300 - 300 mm window, primary sensitivity 3000 mA, secondary 5 A, solid toroidal core, bolt-on mount, epoxy moulded.