Description
I. Product Overview
Woodward 1751-6058 is an original high-precision magnetic pickup unit (MPU) designed for high-speed rotating power equipment such as gas turbines, steam turbines, diesel generator sets and industrial compressors. As the core speed acquisition component of unit speed regulation and overspeed protection systems, it adopts a passive electromagnetic induction structure without external power supply. It converts mechanical rotational speed into standard sine-wave frequency voltage signals and transmits them to governors, protection modules, PLC and DCS systems to realize closed-loop speed regulation, overspeed interlock protection and start-stop logic control.
Featuring an integrated threaded industrial structure, high temperature resistance, vibration resistance, oil pollution resistance and strong anti-electromagnetic interference capability, the product has no internal electronic components, avoiding electronic aging and failure. With ultra-long service life and maintenance-free performance, it is fully compatible with all Woodward speed control systems and widely used in power, oil & gas, chemical and mining industries. It serves as a key original spare part for unit overhaul, faulty sensor replacement and speed measurement system renovation.
II. Hardware Structure and Composition
1. High-flux Magnetic Core Induction Unit
Equipped with a high-permeability permanent magnetic core and precision induction coil, it generates stable continuous sine-wave AC signals when rotating gear teeth cut the magnetic field. The magnetized magnetic core ensures stable magnetic field and excellent signal linearity at both low and high speeds, without signal distortion or amplitude fluctuation, fully adapting to full-range speed measurement of industrial units.
2. Integrated Threaded Metal Housing Structure
Adopting high-strength alloy steel integrated forging structure with standard industrial mounting threads, it features outstanding vibration resistance, impact resistance and deformation resistance. The surface is treated with rust-proof, anti-oxidation and oil-resistant coating, adapting to harsh cabin environments with high temperature, oil pollution and dust, preventing installation gap deviation and signal abnormality caused by shell corrosion and deformation.
3. Shielded Signal Output Cable Unit
Matched with dedicated shielded signal cables with internal insulation and outer shielding layers, it effectively shields electromagnetic interference from frequency converters, high-voltage equipment and ignition devices, eliminating signal clutter, frequency offset and signal loss. The cable and shell are sealed and crimped integrally to prevent oil and water penetration and ensure long-term stable operation of internal induction components.
4. Passive Pure Mechanical Induction Structure
The whole device adopts a pure passive structure without circuit boards, chips or power supply loops, realizing speed measurement through physical electromagnetic induction. It completely avoids failures such as electronic component aging, burnout and system crash, with ultra-high operational reliability, adapting to long-term continuous operation and frequent start-stop working conditions of industrial units.
III. Technical Specifications
(1) Electrical Parameters
Working Principle: Passive electromagnetic induction, no external power supply required
Output Signal: Standard sine-wave AC voltage, amplitude varies with speed and installation gap
Output Voltage Range: 1～30V RMS
Frequency Range: 0～10kHz, suitable for high and low-speed rotating equipment
Signal Linearity: Strict linear correspondence between frequency and speed with negligible error
Insulation Resistance: ≥100MΩ between coil and housing
(2) Mechanical Parameters
Mounting Specification: Standard industrial threaded integrated mounting
Matching Gear: Universal modular industrial speed measuring gear
Optimal Installation Gap: 0.5～1.5mm
Material: High-strength anti-rust and anti-corrosion alloy steel
(3) Environmental Parameters
Operating Temperature: -40℃～+125℃
Storage & Transportation Temperature: -50℃～+135℃
Environmental Resistance: Oil-proof, dust-proof, moisture-proof and anti-corrosion
Vibration Resistance: Compliant with industrial power equipment shock and vibration standards
System Compatibility: Full series of Woodward governors and overspeed protection systems
IV. Product Functions and Features
1. Passive Maintenance-free Design with Ultra-high Reliability
The passive power-free design eliminates all faults related to power supply and electronic component failure. With no vulnerable electronic parts inside, it supports 24/7 uninterrupted unit operation, featuring stable long-term performance, zero drift and extremely low maintenance frequency.
2. Full-range High-precision Speed Measurement
It accurately captures speed changes in unit cranking, rated operation and overspeed critical intervals. The output signal frequency is strictly linear with rotational speed, providing accurate data support for governor PID regulation, overspeed threshold judgment and unit start-stop logic, avoiding speed fluctuation and protection misoperation caused by acquisition deviation.
3. Strong Anti-interference Capability for Harsh Working Conditions
The metal shielded housing and shielded cable design effectively resist strong electromagnetic radiation and high-frequency interference in equipment cabins. It maintains stable waveform and accurate frequency output in complex electromagnetic environments, ensuring precise execution of speed regulation and protection logic.
4. Integrated Threaded Mounting with Wide Compatibility
The standard universal threaded structure fits most turbine, diesel engine and compressor speed measurement bases without structural modification. The adjustable installation gap adapts to gears with different wear degrees, enabling convenient disassembly, assembly and debugging for on-site replacement and maintenance.
5. Original Factory Standard Compatibility
Fully compatible with all Woodward series governors such as 505, 508 and 2301. No program modification or parameter calibration is required after replacement, enabling direct put-into-operation with zero adaptation cost and 100% matching accuracy.
V. Application Scenarios
1. Speed acquisition, closed-loop speed regulation and overspeed safety protection for gas turbines, steam turbines and diesel standby generator sets in thermal and gas power plants.
2. Speed monitoring and interlock protection of large centrifugal compressors and reciprocating units in petrochemical and oil & gas pipeline industries.
3. Speed measurement and start-stop logic control of large high-speed power units and standby power equipment in mining, metallurgy and cement industries.
4. Spare part replacement and precision optimization renovation for aging, unstable or faulty speed sensors of old units.
5. Speed measurement loop upgrading and redundant measuring point expansion for power equipment equipped with Woodward speed control systems.
