Optical probe Electric Current Sensor: OpECS

  • Ultra-small sensor head (Minimum Φ0.45mm)
  • Supports isolation current measurement
  • Wide Bandwidth DC ～ 150MHz
  • Measurable current ±140A
  • Available on oscilloscopes with 50Ω BNC input
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About OpECS *

OpECS is an optical probe current sensor that enables current measurement by capturing the magnetic field generated around the current through the Faraday effect. When a magnetic field exists at the sensor head, the linearly polarized light is affected by the magnetic field and its oscillation direction changes. The direction of oscillation follows an elliptical orbit according to the direction of the magnetic field, and the change in direction is proportional to the magnitude of the magnetic field. The elliptically polarized light information is sent to the main unit (control unit) at the latter stage, where it is converted from an optical signal to an electrical signal. This signal can be input to an oscilloscope or other device equipped with a 50Ω-terminated BNC connector to measure the current.

Principle of Optical current Sensor


 * OpECS is a registered trademark of Citizen Watch Co., Ltd.


Sensitivity and measuring current range of OpECS

【Positional relation between wire and sensor】
Maximum sensitivity is obtained when the sensing element is in contact with the center of the wire, as shown in ① in the lower left figure. For the direction of the current flowing through the wire, a positive output is obtained when placed as in ①, and an inverted output is obtained when placed as in ②. When the sensor is away from the center of the wire as shown in ③, the magnetic field weakens and the sensitivity changes as shown in the lower right figure. Therefore, by maintaining the proper distance, it is possible to measure currents greater than the measurable current.




【Wire diameter and sensitivity】
If the distance between the center of the sire and the sensor is constant, the sensitivity does not change even if the wire diameter is changed, as shown in the figure below.



【linearity】
The linearity of the OpECS current sensor is ±1% and it is maintained up to ±140A.



【Measurable current range】

* Measured by contacting a Φ0.5mm copper wire


OpECS Specifications

Item Specification Note
Frequency bandwidth DC ～ 150MHz (-3dB) －
Measurable current ±140A * Depending on the distance between the sensor and the center of the wire, measurements exceeding the measurable currents listed at left can also be performed.
Sensitivity 25.78 mV/A *
(0.073 mV/A・m-1)		 －
Output voltage range ±4.7V －
Noise 6.3 mVrms With no input, at 200MHz bandwidth instrument
linearity ±1% * －
Output connector BNC Oscilloscope input：50Ω termination **
Operating temperature range -10℃ ～ +50℃ Sensor Head
Operating temperature range +15℃ ～ +35℃ Control Unit
Supply voltage AC100～240V (50/60Hz) －
Power consumption 11W －

* Measured by contacting a Φ0.5mm copper wire
** Can also be used with oscilloscopes with 1MΩ input by using 50Ω feed-through terminations


Dimensions and weight

■ Control Unit

Item Specification Note
Dimensions ( W×L×H ) 158.0×254.0×108.0 mm Protrusions not included
Weight Approx. 2kg －

■ Sensor head

Item Specification Note
Tip shape(Φ×L) Φ0.45×1mm Typical
Weight Approx. 5g －

Order Information

The following two items are required.
■ OpECS main unit (Control unit)
■ Sensor head (Choice of 3 types below)

Name Appearance and Dimensions Forte
Vertical head
Length 50mm, Tip 0.8mm
Horizontal head
Tip Φ0.45mm
IC Clip Head
Measurable when wire-sensor distance is constant