T6050 SurgeGard™ is an incipient surge-conditioning module designed to continuously monitor the high frequency flow, pressure or current oscillations occurring before the compressor reaches the actual surge point(s). SurgeGard™ is patented and has been successfully used in many compressor control systems.
Process Signal Selection
The selection of the proper process signal to detect incipient surge is normally based on the comparison of the incipient signatures of flow, pressure and current (if motor driven machine). In most cases the inlet/outlet flow (h) or current (I or BHP) signal yields the best results. However, some applications use several incipient inputs (flow, pressure, current) and a high-selector function for selection.
Oscillation Signal Description
Before the compressor reaches the surge point (flow reversal), rapid oscillations occur. Compressor field tests have confirmed this phenomenon as an indication of impending surge. However, since this incipient surge phenomenon has special characteristics for each compressor, in practice, it is not always easily measured and SurgeGard™ special signal characterisation is required.
Incipient Surge Oscillation Tests
For the field tests of incipient surge, the pre-amplified transmitter signal is monitored and recorded on a high-speed oscillographic or waveform analyser/recorder. The oscillographic/waveform recorder is a complete multi-purpose instrument featuring two analog inputs and a PC interface.
Lower Experience Level Needed to Implement Incipient Surge Control/Override
The incipient surge test equipment in conjunction with the SurgeGard™ conditioning module provides such a clear indication of surge test onset that incipient surge control can be safely implemented by engineers with less compressor control experience than would otherwise be required. The use of pre-amplified signal in conjunction with the oscillographic verification greatly reduces subjective judgment requirements.
Advantage Over Digital Sampling
The continuous analog peak-detector circuit is more efficient (less than 1 ms) and reliable than the digital sampling (2-10ms sample rate) for both incipient surge control and for surge spike detection. In both applications (analog or digital), high speed transmitters should be used when implementing incipient surge detection techniques.
Field Proven
Incipient surge conditioning has been field proven in many compressor applications. To date, incipient surge tools have been used successfully to perform surge tests, to provide incipient surge control override and to detect surge spikes. The SurgeGard™ is easy to set up and easy to use.
Description of the Conditioning Module
The loop-powered SG-1 SurgeGard™ module consists of a differential input band pass (1Hz to 12Hz) amplifier/filter, a low pass filter (12Hz), absolute-value, peak detector (10 sec) and a voltage-to-current converter; all enclosed in a termination type electronic component housing. The housing is snapped onto commercially available EN mounting rails.
