GCT Circular Residual Current Transformer
GCT-45 Bottom View: Flat bottom with no screw holes.
GCT Circular Residual Current Transformer - Image 3
GCT Circular Residual Current Transformer - Image 4
GCT-45 top view: Display of specifications and label details
GCT Circular Residual Current Transformer - Image 6

GCT Circular Residual Current Transformer

  • Through-core range – Seven aperture sizes from 30 mm to 200 mm support cable circuits with primary currents from 63 A to 2,000 A.
  • Measurement ranges – 50-400 Hz operation, an overall residual-current measurement range of 10 mA-5 A, and an accuracy-assured range of 10% In to 130% In.
  • Signal output – Selectable 0-1 V or 0-0.5 mA rated output for compatible monitoring and protection equipment.
  • Stable sensing – Nickel steel or nanocrystalline core options provide good linearity and sensitivity, while balanced construction helps resist electromagnetic interference.
  • Monitoring applications – Suitable for electrical fire monitoring, leakage systems, small-current grounding, relay protection, microcomputer protection, and intelligent power systems.
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Description

GCT Circular Residual Current Transformer

The GCT circular residual current transformer is a compact through-core sensor for cable circuits. Seven aperture sizes from 30 mm to 200 mm support primary circuit currents from 63 A to 2,000 A. Multiple input, output, and accuracy configurations allow the series to work with compatible residual-current monitoring and protection equipment.

Residual-Current Measurement

The circuit conductors pass through the transformer aperture. Under normal conditions, the magnetic effects of the conductors balance each other. When an unbalanced current occurs, the GCT provides a proportional output signal to the connected monitoring or protection device. Available unbalanced-current output levels can be better than 30 mA, 10 mA, 5 mA, or 3 mA, depending on the selected configuration.

Product Features

  • Through-core construction: Simple, compact structure with aperture sizes matched to different cable arrangements.
  • Encapsulated structure: Flame-retardant epoxy resin casting supports stable internal construction.
  • Magnetic core options: High-permeability nickel steel or nanocrystalline materials provide good linearity and sensitivity.
  • Interference resistance: Balanced characteristics help reduce measurement disturbance caused by the main-circuit magnetic field.

Typical Applications

Typical applications include electrical fire monitoring, fire-prevention and leakage systems, intelligent power systems, small-current grounding systems, electromagnetic relay protection, microcomputer protection, intelligent power equipment, and environmental monitoring.

Selection and Installation

  1. Choose a 30 mm to 200 mm aperture that accommodates all required circuit conductors and the cable arrangement.
  2. Match the nominal residual-current input (In), full-scale output, and accuracy class to the connected monitoring or protection device.
  3. Install the transformer with screw fixation and use the specified terminal connection or 1.5 m shielded twisted wire.
  4. Keep the operating environment within -12°C to +45°C and ambient humidity at or below 85%.
  5. Please contact GEYA for the complete ordering matrix and wiring information for the required aperture and signal interface.

Referenced Standards

The GCT series is specified against GB 14287.2-2005 and GB 14287.2-2014 requirements. Contact GEYA for the current documents applicable to the selected configuration.

Technical Parameters

Electrical parameter Specification
Product model GCT
Product type Circular residual current transformer, through-core type
Through-core aperture 30-200 mm
Primary circuit current 63-2,000 A
Working frequency 50-400 Hz
Nominal residual-current input (In) In = 1 A (0-1 A input span)
Overall residual-current measurement range 10 mA-5 A total sensor response range
Accuracy-assured residual-current range 10% In-130% In (0.1-1.3 A when In = 1 A)
Full-scale output options (at In) 0-1 V or 0-0.5 mA
Ratio difference Within ±0.1%
Phase difference Within ±10 arcmin
Dielectric strength 2.5 kV / 1 mA / 1 min
Insulation resistance DC 500 V / 1,000 MΩ / 1 min

Input terminology: All input figures in this section refer to residual current, not primary circuit current. Nominal residual-current input (In) is 1 A; the associated 0-1 A input span is used for full-scale output and monitoring-host matching. The overall residual-current measurement range is the complete sensor response range from 10 mA to 5 A. The accuracy-assured residual-current range is 10% In to 130% In, which corresponds to 0.1-1.3 A when In = 1 A. Currents above 1.3 A may still be detected up to 5 A, but accuracy is not guaranteed.

Please contact GEYA to match the required input and output interface to the selected aperture and accuracy class.

Mechanical and Environmental Parameters

Mechanical parameter Specification
Shell ABS, flame-retardant grade 94-V0
Skeleton PBT
Iron core Nickel steel or nanocrystalline
Internal structure Environment-friendly epoxy resin casting
Construction plan Screw fixation
Working temperature -12°C to +45°C
Ambient humidity ≤85%
Connection mode Terminal type or 1.5 m shielded twisted wire

Outline and Installation Dimensions

Model and specification Nominal residual-current input (In) Full-scale output Accuracy class Aperture (Φ) A (mm) B (mm) C (mm) D (mm) G
30 In = 1 A (0-1 A input span) 0-1 V (0.5 mA) 0.1 / 0.2 / 0.5 / 1.0 30 mm 87.6 67.8 28 76 M6
45 In = 1 A (0-1 A input span) 0-1 V (0.5 mA) 0.1 / 0.2 / 0.5 / 1.0 45 mm 107.5 83 28 96 M6
65 In = 1 A (0-1 A input span) 0-1 V (0.5 mA) 0.1 / 0.2 / 0.5 / 1.0 65 mm 127.5 105 30 113 M6
80 In = 1 A (0-1 A input span) 0-1 V (0.5 mA) 0.1 / 0.2 / 0.5 / 1.0 80 mm 159.5 128 32 145.5 M6
100 In = 1 A (0-1 A input span) 0-1 V (0.5 mA) 0.1 / 0.2 / 0.5 / 1.0 100 mm 188 154 32 174 M6
150 In = 1 A (0-1 A input span) 0-1 V (0.5 mA) 0.1 / 0.2 / 0.5 / 1.0 150 mm 234 200 32 220 M6
200 In = 1 A (0-1 A input span) 0-1 V (0.5 mA) 0.1 / 0.2 / 0.5 / 1.0 200 mm 284 252 32 270 M6

FAQs

What is the GCT circular residual current transformer?

GCT is a through-core transformer that senses residual or unbalanced current in cable circuits and supplies a proportional signal to compatible monitoring or protection equipment.

Which aperture sizes and primary circuit currents are available?

The series includes 30 mm, 45 mm, 65 mm, 80 mm, 100 mm, 150 mm, and 200 mm apertures for primary circuit currents from 63 A to 2,000 A.

Why are both 0-1 A and 10 mA-5 A shown in the specifications?

They describe different parts of the input specification, and both refer to residual current rather than the primary circuit current. The model matrix uses nominal residual-current input (In = 1 A) and shows its associated 0-1 A input span for monitoring-host matching and full-scale output. The electrical table uses overall residual-current measurement range for the complete sensor response range from 10 mA to 5 A. The accuracy-assured range is 10% In to 130% In, or 0.1-1.3 A when In = 1 A; currents above 1.3 A may still be detected up to 5 A, but accuracy is not guaranteed.

Which accuracy classes are available?

The model matrix includes accuracy classes 0.1, 0.2, 0.5, and 1.0. Select the class according to the connected monitoring or protection equipment and the project measurement requirements.

How does the GCT help reduce false alarms?

Its balanced magnetic structure and electromagnetic-interference resistance help limit measurement disturbance from the main-circuit magnetic field. Available unbalanced-current output levels can be better than 30 mA, 10 mA, 5 mA, or 3 mA.

Where can the GCT series be used?

Typical uses include electrical fire monitoring, fire-prevention and leakage systems, intelligent power systems, small-current grounding, relay protection, microcomputer protection, and environmental monitoring.

What installation conditions should be checked?

Select the aperture for the cable arrangement, use screw fixation, and confirm the terminal or shielded-wire connection. The specified working temperature is -12°C to +45°C, with ambient humidity at or below 85%.

Which standards are referenced for the GCT series?

The product information references GB 14287.2-2005 and GB 14287.2-2014. Contact GEYA for the current documents applicable to the selected configuration.

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