WOODWARD 1680‑622 Electromagnetic Speed Sensor

Basic Information

Part Number: 1680‑622 Device Name: Magnetic Pick‑Up (MPU) Device Type: Passive magnetic speed sensor, no external power supply required Application: Diesel / gas engines, steam turbines; provides speed signal for Woodward governors and controllers for speed measurement, overspeed protection and governing control.

Key Electrical & Mechanical Parameters:

• DC Coil Resistance: 250 Ω
• Max Output Voltage: 60 Vpp
• Thread Specification: 0.625‑18 UNF
• Probe Effective Length: 2.5 inch
• Coil Configuration: Single coil
• Operation Principle: Passive induction; AC signal generated when gear teeth cut magnetic field
• Compatible Controllers: Woodward 2301, 505, EPG, Easygen and other governor/genset controllers
• Operating Temperature: ‑40℃ ~ +125℃
• Lifecycle: New original parts available from OEM; second‑hand spare parts also circulating on market.

Main Functions

1. Detect speed of flywheel / toothed gear, output sinusoidal AC speed signal
2. Provide actual speed feedback for governing control system
3. Participate in overspeed protection logic
4. No external power needed; signal generated by magnetic induction.

Installation & Compatibility Notes

1. Installation gap: Standard clearance between probe tip and gear tooth top 0.5‑1.0 mm. Output voltage highly depends on gap. Too large gap leads to weak signal; too small gap may cause mechanical collision and damage the sensor.
2. Thread: 0.625‑18 UNF, install with lock nut.
3. Passive sensor, do NOT apply DC power supply; DC voltage will burn internal coil.
4. Reference sibling model: 1680‑649 (3‑inch length version). Same thread & resistance, different probe length; not directly interchangeable.
5. Shielded twisted‑pair cable is recommended to mitigate field EMI interference.

Common Fault Symptoms

• No speed output: Coil open circuit, probe collision damage, broken wiring
• Fluctuating jumping speed reading: Excessive installation gap, damaged shielding, defective gear teeth