OpECS - Optical Electric Current Sensor - 150 MHz, >140 A, no derating

OpECS is an optical current sensor that measures current by detecting the magnetic field around a conductor via the Faraday effect, with galvanic isolation between sensor and instrument ground.

• Ultra-small sensor head (minimum Φ0.45 mm)
• Bandwidth DC to 150 MHz
• Measurable current ±140 A (depends on sensor placement)
• Output for oscilloscopes with 50 Ω BNC input
• Main unit plus interchangeable sensor head required

Working principle

Linearly polarized light in the sensor head rotates when a magnetic field is present. The control unit converts the optical information to an electrical signal routed to a 50 Ω-terminated BNC input on an oscilloscope or acquisition system.

Sensitivity and current range

Maximum sensitivity is achieved when the sensing element contacts the center of the conductor. As distance increases, field strength drops and sensitivity follows—allowing correlated measurement of higher bus currents. Output polarity depends on current direction and sensor orientation.

Wire diameter

With fixed spacing between wire center and sensor, sensitivity remains essentially unchanged when wire diameter changes.

* Typical value when contacting a Φ0.5 mm copper wire; greater currents can be measured at increased spacing. 1 MΩ oscilloscope inputs can be used with 50 Ω feed-through terminations.