Key Information of Woodward ProTech 203 Overspeed Protection System Model
9907-147
1. Basic Product Positioning
The 9907-147 is a specific variant of the Woodward ProTech 203 Overspeed Protection System, a digital overspeed trip device designed for prime movers such as engines and turbines. Its core function is to continuously monitor prime mover speed through three independent magnetic pickups (MPUs) and activate a trip signal to prevent damage or safety hazards caused by overspeed. It adopts a "two-out-of-three" voting configuration, which means a trip is only triggered when two of the three speed-sensing units detect an overspeed condition, ensuring high reliability and avoiding false trips due to single-unit failures.
2. Regulatory Compliance
The 9907-147 meets multiple regional and international standards for safe operation. In North America, it is UL Listed for use in Class I, Division 2, Groups A, B, C, and D locations (with a T3C temperature rating at 60 °C ambient, UL File E156028) and can also be used in non-hazardous locations. For European markets, it complies with EN60079-15 (Electrical apparatus for explosive atmospheres – Type of protection ‘n’), making it suitable for Zone 2, Group II environments.
In terms of directive compliance, it adheres to the EMC Directive (89/336/EEC and its amendments, meeting EN50081-2 and EN50082-2 standards), the Low Voltage Directive (73/23/EEC), and the ATEX Directive (94/9/EEC for equipment used in potentially explosive atmospheres). Wiring for the 9907-147 must follow North American Class I, Division 2 or European Zone 2 wiring methods, as applicable, and comply with the requirements of the local authority having jurisdiction (AHJ).
3. Core Technical Specifications
3.1 Power & Physical Parameters
The 9907-147 is a de-energize-to-trip model, a design recommended by Woodward for general safety—this means it trips when power is lost, preventing prime mover runaway that could occur with energize-to-trip models. Its input voltage is 24 Vdc, with an acceptable range of 18–32 Vdc, and it has a power consumption of 5.12 W.
The enclosure of the 9907-147 is rated Type 4 and 4x for North America and IP54 for Europe, providing protection against environmental factors. The core system operates within a temperature range of –25 to +60 °C (–13 to +140 °F), while the display functions properly between –15 to +60 °C (+5 to +140 °F). The unit weighs 7.3 kg (16 lbs) and meets US MIL-STD-810D standards for vibration (Method 516.3, Procedure I) and humidity (Method 507.2, Procedure II).
3.2 Speed Sensing & Trip Performance
The 9907-147 relies on three independent magnetic pickups (MPUs) for speed sensing, with each MPU input having an impedance of 2 kΩ. It can sense speeds ranging from 100 Hz to 32 kHz and has a trip-point frequency range of 250 Hz to 25 kHz (this can be converted to rpm based on the programmed number of MPU gear teeth). The minimum MPU input amplitude required is 1 Vrms for frequencies between 100 Hz and 25 kHz, and 2 Vrms for frequencies between 25 kHz and 32 kHz, with a maximum input amplitude of 25 Vrms.
The trip accuracy of the 9907-147 is ±(0.05% × Trip Point in Hz + 2 Hz). It samples speed every 5 milliseconds, with a maximum total response time of 40 ms. For MPU fail protection, the MPU Fail Setpoint (100–25,000 rpm) and MPU Fail Timeout (1 second to 533 minutes 20 seconds) are programmable—if the prime mover speed does not exceed the MPU Fail Setpoint within the MPU Fail Timeout period, the unit will trip.
3.3 Output Ratings
For trip relay contacts (de-energize-to-trip), the 9907-147 has different current ratings based on load type and voltage. For resistive loads, it handles 10.0 A at 28 Vdc and 3.0 A at 115 Vrms (50/60 Hz). For inductive loads, it supports 1.0 A at 28 Vdc and 2.0 A at 115 Vrms (50/60 Hz). Tungsten loads see 1.0 A at 28 Vdc and 0.5 A at 115 Vrms (50/60 Hz), while motor loads are rated at 3.0 A at 28 Vdc and 1.5 A at 115 Vrms (50/60 Hz).
The alarm relay contacts, which de-energize during a trip (and momentarily after reset or power-up), handle 2.0 A at 28 Vdc and 0.3 A at 115 Vrms (50/60 Hz) for resistive loads. It is important to note that an alarm only indicates a situation requiring attention and is not the same as a trip
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