The Woodward DSS-2 (Digital Speed Switch) is a versatile, microprocessor-based controller designed to monitor rotational speeds and provide critical protection for industrial engines and turbines. By utilizing magnetic pickups or other speed sensors, the DSS-2 offers precise control over overspeed and underspeed conditions through two independent relay channels.

 

Product Overview

This 2-channel digital speed switch is engineered for high reliability in rugged environments. It effectively replaces older analog speed switches, offering superior accuracy and easier configuration. The device is commonly used to trigger alarms, initiate engine shutdowns, or control secondary equipment based on specific RPM thresholds.

 

Technical Datasheet

General Specifications

• Product Name: Woodward DSS-2
• Part Type: 2-Channel Digital Speed Switch
• Input Voltage: 9–30 VDC (Compatible with 12V and 24V systems)
• Input Signal: Magnetic Pickup (MPU) or Proximity Switch
• Frequency Range: 5 Hz to 25,000 Hz
• Relay Outputs: Two Form C (SPDT) dry contacts
• Contact Rating: 10 A at 28 VDC / 10 A at 115 VAC
• Operating Temperature: -40°C to +85°C
• Dimensions: 115mm x 90mm x 45mm
• Weight: 0.45 kg
• Country of Origin: USA

 

Application Fields

• Engine Protection: Monitoring for overspeed conditions to prevent catastrophic mechanical failure.
• Generator Sets: Controlling the engagement of starters or signaling when the engine is at “rated speed.”
• Industrial Turbines: Providing independent backup speed sensing for safety-critical systems.
• Pump & Compressor Stations: Automating the sequence of operation based on mechanical rotation.

 

Product Instructions

• Installation: Mount the DSS-2 on a flat surface or within a control panel. Ensure the wiring is separated from high-voltage AC lines to prevent signal interference.
• Calibration: The unit can be programmed via a handheld programmer or specialized software. Set the number of gear teeth and the desired RPM setpoints for both Channel 1 and Channel 2.
• Relay Logic: Configure the relays as “Normally Energized” or “Normally De-energized” based on your fail-safe requirements.
• Verification: Use a frequency generator or perform a controlled low-speed test to verify that the Woodward DSS-2 accurately triggers at the specified thresholds.

Q&A: Frequently Asked Questions

• Q: Can the DSS-2 share a speed sensor with a governor?
  • A: While possible, it is highly recommended to use a dedicated magnetic pickup for the DSS-2 to ensure independent safety monitoring.
• Q: What happens if the speed sensor signal is lost?
  • A: The DSS-2 features signal-loss detection logic. Depending on the configuration, it can trigger an alarm or a shutdown if the input frequency drops unexpectedly.
• Q: How do I reset the switch after an overspeed trip?
  • A: The unit can be configured for “Manual Reset” (requiring a physical button press or power cycle) or “Auto Reset” (resetting once the speed drops below the setpoint).
• Q: Is the DSS-2 compatible with Proximity Switches?
  • A: Yes, it supports both standard two-wire magnetic pickups and three-wire proximity sensors.

 

Recommended Similar Models

• Woodward DSS-1 (Single Channel Version)
• Woodward 8270-1017 Speed Control
• Woodward 1700-Series Magnetic Pickups
• Dynalco SST-2000 Speed Transmitter
• Barber Colman DYN2-80108 Speed Switch