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DC current sensor for Measurement of Geomagnetically Induced Currents in Electrical Grid and Electrical Distribution Networks

DC Current Sensor


  1. High resolution (1000:1)
  2. Low residual offset
  3. Split-core
  4. Bidirectional
  5. Non-contact
  6. Input/Output isolation
  7. Low power consumption
  8. Outdoor installation
  9. Wide temperature range
  10. Conduit attachment (Rigid 1/2” 12.7mm dia)


CTH-GIC transducers are able to measure DC currents in the presence of higher levels of AC. This enables accurate measurement of Geomagnetically Induced Currents (GIC) on power grids and DC components potentially harming and degrading distribtion equipment. The device operates over a wide dynamic range and maintains low-level accuracy even after a large over-range. The GIC’s inherently low residual effect eliminates the need to degauss in all but extreme circumstances. The split-core enclosure, with captive hardware and outdoor rating, makes installation easy and does not require circuit interruption.

Why measure Geomagnetically Induced Currents (GICs)

Geomagnetically Induced Currents (GICs) can result from geomagnetic storms, which is a type of space weather event in which Earth's magnetic field is disturbed by incoming magnetic solar material. Most GICs are triggered by coronal mass ejections, or CMEs, which interact with the magnetic field around Earth and cause it to temporarily "rattle". The quick-changing magnetic fields electromagnetically induce currents in long electrical conductor installations like grid and distrbution networks. GICs can flow also through railroad tracks, underground pipelines and power grids. In extreme cases, they can cause power outages like brownouts and in some cases blackouts.

Product Specifications


  • Current Range - See model selection
  • Over-range (w/o damage) >8000A
  • Bandwidth (1.5Hz low pass filter on output) dc to 1.5Hz


  • Models B, D, X5 0 to ±FS dc in = 0 to ±FS out
  • Model EM -FS dc/0/+FS dc in = 4/12/20mAdc out
  • Model E (unidirectional) 0-FS dc in = 4-20mAdc out
  • Models E and EM 0-500Ω
  • Model B 0-10kΩ
  • Models D and X5 ≥2kΩ
Response time (90%)
  • < 350ms (typical)

Instrument Power

  • Standard 24Vac/24Vdc, ±10%
  • Option “-12” 12Vac/12Vdc, ±10%
  • Current nominal 80mA
  • Current maximum 100mA


  • Linearity, offset, setpoint and repeatability ≤0.5% F.S.
  • Over-range residual offset 0.0007A/A of input current
    (max offset = 350mA)
  • Linearity ≤0.1%F.S.


  • Operating range -40°C to +85°C
  • Temperature effect ±0.025%/°C
  • Storage -40°C to +85°C


  • Weight 2.0lbs

Model Selection

Ordering information

Example: 600Adc Input 0-±1mAdc Outputs CTH-GIC-601B

XXX DC Range Z Output Type
051 ±0-50Adc B 0-±1mAdc
101 ±0-100Adc D 0-±10Vdc
151 ±0-150Adc X5 0-±5Vdc
201 ±0-200Adc E 4-20mAdc
301 ±0-300Adc EM 4/12/20mAdc
401 ±0-400Adc
501 ±0-500Adc
601 ±0-600Adc
801 ±0-800Adc
102 ±0-1000Adc
122 ±0-1200Adc
152 ±0-1500Adc

Case dimensions

Dimensions are in inches
Tolerance is ±0.03 inches

Case Dimensions

Connection Diagram

Connection Diagram