Soft Shutdown satellite Qualification Safety System
A Vibration Test System that Protects Against the Unexpected
From the ground up, Data Physics and NVT Group partner company Team Corporation have engineered and refined a test safety system capable of protecting valuable test articles from unexpected events – even a complete loss of 480 V power. Complete design control of all components – vibration controllers, shakers, amplifiers and accessories – ensures the system’s exceptional ability to detect potential failures and reliably protect valuable flight hardware.
Ready for all Contingencies
The soft shutdown safety system executes a controlled, transient-free shutdown during in all test stop conditions – those that are predictable and those that are typical unpredictable. These include:
- Complete, sudden loss of 480V power to the amplifiers
- Hydraulic pressure loss for guidance bearings
- Control PC crash or power loss
- Amplifier trip on overcurrent, overvoltage, or over travel
- Typical control or limit/notch tolerance abort
- External measurement system abort trigger
How the System Works
Data Physics’ and our NVT Group partner company Team Corporation’s complete design control of all components – vibration controllers, shakers, amplifiers, guidance bearings, and accessories – enables us to develop a comprehensive safety system with all components working together to protect the test article.
All shutdowns – whether triggered by an interlock, loss of power, or a tolerance abort – are executed by the vibration controller.
Each component in the soft shutdown system has been modified to handle failures gracefully – they signal the controller to shut down instead of abruptly stopping on their own.
Each component is also over designed, and able to execute the soft shutdown after a normally-catastrophic failure, such as a loss of 480V power.
Previously Independent Subsystems, Now Functioning in Unison
Shaker/Amplifier Synergy
- All interlock signals controller to immediately trigger a soft shutdown
- Interlocks do not abruptly shut down the amplifier – they gradually shut down the field allowing time for a soft shutdown
- 480V power health is continually monitored – and any failure triggers the controller to shut down
- Amplifier fitted with extra capacitors to function after 480V power failure
Hydraulic Guidance
Hydraulic pressure health monitored electronically at key locations.
- A drop in hydraulic pressure signals the controller to immediately trigger a soft shutdown
- Hydraulic system is fitted with extra accumulators to function in the case of any failures or loss of power
Vibration Controller
The vibration controller plays a critical role in the Soft Shutdown system – it controls every ramp down regardless of what triggers it.
- All shutdowns – whether triggered by an interlock, loss of power, or a tolerance abort – are executed by the vibration controller.
- The vibration controller is optimized to initiate the ramp down quickly – with minimal latency
- The controller executes a controlled ramp down in a pre-defined time
- The pre-defined ramp down time ensures the amplifiers’ extra capacitors will not run out of charge ; and the hydraulic accumulators will not lose pressure in the event of a 480V power loss
Analysis System
A 900 Series measurement system is an additional part of the soft shutdown system; monitoring hundreds or thousands of channels. The measurement system can quickly trigger the controller to issue a soft shutdown, based on the acquired data.
- Sine Data Reduction – Control / Abort profiles can be entered into the Analyzer; and the Analyzer can trigger the Controller to shut down if any tolerances are exceeded.
- Monitor (gap-free) for Transients – To trigger a soft shutdown if any are detected.
- Multi-Measurement – run secondary measurements (such as FFTs) live during a test. Generate waterfalls live during test to visualize harmonic distortion, for example. All without the need to post process.
Cutting the Power
During execution of a Sine sweep on a 50,000lbf shaker, the 480V power was abruptly cut. One would expect to see a large transient imparted onto the armature, with potentially damaging results. But that did not happen here – this is a soft shutdown shaker system.
Below is data from that test. The test was performed on a Data Physics soft shutdown vibration test system. The system utilized a 50,000 lbf. electrodynamic shaker, a SignalForce power amplifier, and was driven by our controller. The plots show the controller’s drive output; the acceleration measured at the armature, and the voltage driving the armature. The test was ramped down, imparting no transients onto the armature.
